ICSE 2025

BIOLOGY
Including Case Based Questions

CLASS 10

Chapter-wise Question Bank

Based on Previous 20 Year 54 Papers

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ICSE Biology Question Bank Class 10
Edition December 2024
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 CONTENTS
CHAP 1. Cell Cycle and Structure of Chromosomes 5-43

CHAP 2. Genetics 44-67

CHAP 3. Absorption by Roots 68-114

CHAP 4. Transpiration 115-151

CHAP 5. Photosynthesis 152-189

CHAP 6. Chemical Coordination in Plants 190-207

CHAP 7. The Circulatory System 208-256

CHAP 8. The Excretory System 257-281

CHAP 9. Nervous System and Sense Organs 282-320

CHAP 10. The Endocrine System 321-347

CHAP 11. The Reproductive System 348-384

CHAP 12. Human Population 385-406

CHAP 13. Human Evolution 407-421

CHAP 14. Pollution 422-442

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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 5

CHAPTER 1
CELL CYCLE AND STRUCTURE OF CHROMOSOMES

1. CELL DIVISION 4. MITOTIC PHASE OR MITOSIS (DIVIDING PHASE)

Cell Division is a method by which new cells are It is the dividing phase during which nucleus as
originated from pre-existing cells. These new cells well as cytoplasm divide into two daughter cells.
need to be produced for growth, development, It is studied in two parts :
replacement, repair and reproduction. All (i) Karyokinesis (ii) Cytokinesis
organisms contain an even number (2n) of (i) Karyokinesis (Division of nucleus) : In this
chromosomes in their somatic or body cells. The many events take place in a sequence which
cell division leading to growth, development, are studied in four stages.
repair and replacement is called Mitosis. The cell 1. Prophase : It begins with the appearance
division leading to production of gametes (sex of chromosomes which have become
cells) is called meiosis. short, thick and clearly visible inside the
nucleus. Each chromosomes get duplicated
2. CELL CYCLE by splitting longitudinally to form two
The sequence of events including growth and chromatids which are attached to each
division, that a cell undergoes from the time of other at a small region called centromere.
its formation upto its division into daughter cells The centrosome (in animal cell) splits into
is called cell cycle. Every cell capable of division two along with duplication of centrioles
passes through cell cycle which consists of two which move towards opposite poles of
phases : the cell. Each centriole is surrounded
1. Interphase [Resting or non-dividing phase; I by asters (centrioles along with astral
phase] rays). A number of spindle fibres appear
2. Mitotic phase or Mitosis [Dividing phase; M between two daughter centrioles.
phase] In plant cell due to the absence of
centrosome (centriole), the formation of
3. INTERPHASE (RESTING PHASE) spindle fibres take place from cytoplasmic
It is the non-dividing preparatory phase during strands (microtubules) of the cell.
which a cell grows to its maximum size (by The nuclear membrane and nucleolus
increase in volume of nucleus and nucleolus) and disappear. The chromosomes start
the synthesis of DNA (chromosome material) moving towards equator of the cell.
takes place. Due to the duplication of DNA 2. Metaphase : The chromosomes get
contents the chromatin material also duplicates . arranged at the equatorial plate of the
Interphase is divided into three sub-stages. cell. Each chromosomes get attached
(a) G1 – phase : Volume of cytoplasm increases itself to a spindle fibre by its centromere.
and protein synthesis takes place. 3. Anaphase : Centromere divides and two
(b) S – phase : Synthesis of DNA takes place. sister chromatids of each chromosome
(c) G2 – phase : Necessary spindle proteins are separate and are drawn apart towards
synthesized. opposite poles to form two groups of
The cell is quite active metabolically during chromosomes.
this phase and several processes, including DNA 4. Telophase : Each Chromatid or daughter
synthesis, occur at this time, thus no alternative chromosome turns into a network of
is left for the cell except to divide by the process chromatin threads. Nuclear membrane
of mitosis. and nucleolus reappear.
(ii) Cytokinesis (Division of cytoplasm) : A
constriction (furrow) appears in the cell
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

membrane at the middle of the animal cell,

which deepens and finally splits the cytoplasm
into two, thus producing two new cells. In
plant cell instead of a furrow, a cell plate is
laid down in the cytoplasm at the equatorial
plate. It grows from centre to periphery, thus
dividing the original cell into two daughter
cells.
Note : In Mitosis, two identical daughter
cells are produced by division of one parent
cell. The main aspect of this division is that
the same normal chromosome number is
maintained at each division of the cell. Hence,
it is also called as Equational cell division.
Identification points of Mitosis :
1. Prophase – Chromosomes with two
chromatids, disappearance of nuclear
membrane as well as nucleolus and formation
of the spindle.
2. Metaphase – Chromosomes arranged at
equatorial plate.
3. Anaphase – Movement of daughter
chromosomes towards pole.
4. Telophase – Uncoiling of chromosomes,
disappearance of spindle, reappearance of 4.1 Significance of Mitosis
nucleolus and nuclear membrane.
The Significance of Mitosis are as follows :
Differences between mitosis in animal and plant
1. Helps in growth of animals and plants.
cell are as follows :
2. It replaces old and dead cells.
Animal cell Plant cell 3. Repairs damaged and wounded tissues of
animals and plants.
1. Spindle formed is 1. Spindle formed is
4. Helps in asexual reproduction in unicellular
amphiastral. anastral.
organisms.
2. Cytokinesis by 2. Cytokinesis by 5. Maintains same number of chromosomes in
constriction formation of cell daughter cells.
(furrow) method. plate.
5. MEIOSIS
3. Cytokinesis 3. Cytokinesis
It is the kind of cell division that produces sex
proceeds from proceeds from
cells or gametes. It takes place in the reproductive
outside to centre. centre towards
organs, i.e., testis to produce sperms and ovary
periphery.
to produce egg or ovum in humans. In Plants, it
4. Centrosome 4. Centrosome takes place in anthers to produce pollen grains
present so 2 absent so no and ovules in ovary to produce egg or oosphere.
asters are formed. asters are formed. The number of chromosomes in this type of cell
division is reduced to half in the daughter cells.
Meiosis consists of two separate divisions of sex
cells:
(i) Meiosis I (Heterotypic or reductional division)
: This division is meiotic in which the
chromosome number is reduced to half (n).
(ii) Meiosis II (Homotypic or equational division)
: This division is mitotic. Each of the two
cells formed in meiosis I further divides
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 7

into two, resulting in the formation of four The chromosomes consist of about 40% DNA
daughter cells, each with haploid (n) number and about 60% histones (a particular type of
of chromosomes. protein). The histones and DNA form a kind of
complex in which the DNA strands wind around
5.1 Significance of Meiosis histone molecules. Each such complex is called
Significance of Mitosis are as follows : nucleosomes. A single human chromosome may
1. In sex cells (gametes), chromosome number have about a million nucleosomes.
is halved so that on fertilization the normal The DNA is a very large single molecule
number (2n) is restored. (macromolecule) which is composed of two
2. Helps in mixing up of genes which increases strands, wound around each other in a double
the genetic vigour. helix manner.
3. Helps in causing variations which further
leads to evolution. 6.1 Nucleic Acid
Differences between Mitosis and Meiosis are as Chemical analysis of chromosomes show two nucleic
follows : acids DNA and RNA. They were first discovered
by Frederick Miesher. Nucleic acids have complex
Mitosis Meiosis chemical structures composed of pentose sugars,
1. Occurs in somatic Occurs in nitrogenous bases and phosphates. The DNA and
cells of haploid reproductive cells of RNA differ from each other as follows :
as well as diploid diploid organisms
organisms. only. DNA RNA

2. It produces two It produces four 1. Found in nucleus, Found in cytoplasm,

daughter cells. daughter cells. mitochondria and nucleolus and
chloroplast. chromosomes.
3. It is completed in It is completed
one division. in two successive 2. Pentose sugar is Pentose sugar is
divisions. deoxyribose. ribose.

4. It is equational It is reductional 3. Mostly double Mostly single

division. division. stranded. stranded.

5. Genetic constitution Genetic constitution 4. Concerned with Concerned with

of daughter cells of daughter cells genetic information. synthesis of
remains the same. becomes different. proteins.

6. No synapsis takes Synapsis occurs

6.2 Genes
place. during prophase I.
The specific parts of chromosomes, which are
7. No crossing over Crossing over takes
composed of DNA are called Genes. They
takes place. place in prophase I.
determine hereditary characters. They are
8. It takes place It takes place responsible for transmission of characters from
during growth, during reproduction one generation to another. They are located in
repair, regeneration of an organism. the chromosomes and occupy a fixed position in
and development of the chromosome. Scientists have identified around
an organism. 1,30,000 genes in human chromosomes.
Every human body cell has the same number
6. CHROMOSOMES of chromosomes and possesses nearly all normal
These are small but thick, rod like darkly stainable genes. Some of the genes are active in all the
structures seen in the nuclei of dividing cells only cells such as genes for cell respiration, as every
at metaphase and anaphase stage of cell division. cell needs to respire. Some genes though present
Hofmeister discovered chromosomes for the first in all the cells are active only in the particular
time. Each chromosome in its condensed form specialized body cells such as, genes for producing
consists of two chromatids joined at one point insulin is present in every cell but functionally it
called centromere and the parts of chromatids on expresses only in beta cells of islets of langerhans
the two sides of a centromere are called arms. of pancreas.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

6.3 Types of Chromosomes

MULTIPLE CHOICE QUESTION
Chromosomes are divided in the following parts :
1. Metacentric : Centromere in the centre and
two arms of chromatid are equal. 1. Duplicated chromosomes are joined at a point
2. Submetacentric : Centromere slightly away termed:
from centre and one arm of chromatid is (a) Centrosome (b) Centromere
slightly larger than other. (c) Centriole (d) Chromatid
3. Acrocentric Centromere is present near one Ans : MAIN 2024
end of chromatid and one arm is very large
than the other. Duplicated chromosomes consist of two identical
4. Telocentric : Centromere is present at one end sister chromatids joined together at a point called
of chromosome. the centromere.
Thus (b) is correct option.

2. A female human cell divides through mitosis,

maintaining the same number of chromosomes.
Consider the chromosome composition of the
daughter cells after mitosis. After Mitosis, a
female human cell will have :
(a) 44 + XX chromosomes.
(b) 22 + X chromosomes.
(c) 22 + Y chromosomes.
7. TELOMERE (d) 44 + XY chromosomes.
Telomere is terminal end of chromosome that Ans : COMP 2021
consists of many copies of a repeated DNA If a female cell with 44+XX chromosomes divides
sequence. mitotically, it will form 2 daughter cells with
The chromosomes which determine the sex of an similar chromosomes i.e. 44+XX whereas a male
individual are called allosomes or idiosomes or sex cell will mitotically divide to form cells with
chromosomes. The 23rd pair of human chromosomes chromosome 44+XY
(X and Y) are called as sex chromosomes. Thus (a) is correct option.
1 – 22 pairs of human chromosomes are called as
autosomes. 3. At the end of______Cytokinesis is completed.
The chromosome number of some common animals (a) Metaphase (b) Prophase
and plants organisms in pairs are as follow : (c) Interphase (d) Telophase

1. Ascaris = 1 pair Ans : SQP 2021

2. Frog = 13 pairs Cytokinesis begins in anaphase and ends in

telophase, reaching completion as the next
3. Humans = 23 pairs interphase begins.
4. Gorilla = 24 pairs Thus (d) is correct option.
5. Rabbit = 22 pairs 4. The nitrogenous base Adenine always pairs
6. Rat = 21 pairs with______.
7. Lion, tiger and cat = 19 pairs (a) Thymine (b) Guanine
(c) Cytosine (d) Thiamine
8. Dog and fowl = 39 pairs
Ans : MAIN 2021
9. Onion = 8 pairs
Adenine pairs with Thymine in DNA through
10. Maize = 10 pairs two hydrogen bonds, maintaining the double-
11. Potato = 24 pairs helix structure. This pairing follows specific base-
12. Garden Pea = 7 pairs pairing rules, ensuring accurate DNA replication.
The Adenine-Thymine pairing complements the
Guanine-Cytosine pairing.
Thus (a) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 9

5. Replication of DNA in the cell cycle occurs during distribution of chromosomes is:
the : (a) Splitting of the centromeres
(a) G1 - phase (b) Anaphase (b) Splitting of the chromatids
(c) S - phase (d) G2 - phase (c) Replication of the genetic material
(d) Condensation of the chromatin
Ans : MAIN 2021

S-phase is the period during which DNA Ans : MAIN 2017

replication occurs. Anaphase is marked by splitting of centromere

Thus (c) is correct option. and contraction of spindle fibers which in turn
move the sister chromatids towards the opposite
6. State the functions of Centromere : poles.
(a) It is the point of attachment of two sister Thus (a) is correct option.
chromatids.
(b) It is the point of attachment of two centrioles. 10. Which of the following descriptions of mitosis is/
(c) It is the point of attachment of two are correct?
centrosomes. (i) DNA synthesis occurs at the beginning of
(d) It is the point of attachment between two prophase.
daughter nuclei. (ii) The nuclear envelope breaks down in prophase
and reforms in telophase.
Ans : COMP 2021
(iii) The division of centromeres occurs in
The centromere is a region on a chromosome that anaphase.
links two sister chromatids. During cell division, (a) 1, 2 and 3 (b) Only 1 and 2
it also serves as the attachment point for spindle (c) Only 2 and 3 (d) Only 1
fibers, ensuring proper segregation of chromatids
to daughter cells. Ans : SQP 2010

Thus (a) is correct option. Mitosis is a cell division in which a single cell
divides into two identical daughter cells. In
7. The cell component visible only during cell prophase, the nuclear envelope breaks down and
division ______ reforms in telophase. The division of centromeres
(a) Mitochondria (b) Chloroplast occurs in anaphase.
(c) Chromosome (d) Chromatin Thus (c) is correct option.
Ans : SQP 2013
11. The stage in which daughter chromosomes move
The genetic material, i.e. DNA, is present as toward the poles of the spindle is:
chromatin fibres in a non-dividing cell. Only during (a) Anaphase (b) MetaPhase
particular stages of cell division are chromosomes (c) Prophase (d) TeloPhase
visible. The coiling and supercoiling of chromatin
fibres forms chromosomes. Because chromosomes Ans : COMP 2022

are substantially condensed during cell division, In anaphase, the centromere splits and
they can be seen under a light microscope. chromosomes move apart towards two opposite
Thus (c) is correct option. poles due to shortening of spindle fibers.
Thus (a) is correct option.
8. Chromosomes get aligned at the centre of the cell
during : 12. During cell division, a specific cell component
(a) Metaphase (b) Anaphase becomes distinctly visible, aiding in the
(c) Prophase (d) Telophase. distribution of genetic material. This component
is otherwise not clearly seen in non-dividing
Ans : SQP 2015
cells. The cell component visible only during cell
Attachment of chromatids to the mitotic spindle division.
and chromatid alignment on the equatorial plate (a) Mitochondria (b) Chloroplast
are both part of metaphase. (c) Chromosome (d) Chromatin
Thus (a) is correct option.
Ans : MAIN 2019
9. The major event that occurs during the anaphase The cell component visible only during cell
of mitosis, which brings about the equal division is the chromosome. The highly condensed
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

and coiled chromatin fibers which appear during Ans : MAIN 2002

karyokinesis are called chromosomes. Mitosis is used to produce daughter cells that
Thus (c) is correct option. are genetically identical to the parent cells. The
cell copies – or ‘replicates’ - its chromosomes (as
13. Which of the events listed below is not observed well as the genes), and then splits the copied
during mitosis? chromosomes equally to make sure that each
(a) Chromatin condensation daughter cell has a full set.
(b) Movement of centrioles to opposite poles Thus (b) is correct option.
(c) Appearance of chromosomes with two
chromatids joined together at the centromere. 17. Spindle fibres play an important role in mitosis
(d) Crossing over and meiosis. Which biological molecule are spindle
Ans : SQP 2005
fibres composed of?
(a) Polysaccharide (b) Protein
Crossing over occurs during prophase I of meiosis. (c) nucleic acid (d) Lipid
Thus (d) is correct option.
Ans : SQP 2000
14. Which kind of cell division taking place in each of Spindle fibers also known as mitotic spindle are
the following options is incorrect? the cellular structures which are mainly used
(a) At the tip of the root : Mitosis during cell division. It forms a protein structure
(b) To produce pollen grains : Meiosis which helps in cell division. It is made up of
(c) To add girth to the stem : Mitosis tubulin protein.
(d) To produce egg: Mitosis Thus (b) is correct option.
Ans : COMP 2009
18. Two daughter cells formed during mitosis contain
Female gametes are called ova or egg cells and (a) the same amount of DNA,S but a set of
male gametes are called sperm. These reproductive chromosomes different from those of the
cells are produced through a type of cell division parent cell.
known as meiosis. (b) the same amount of DNA and the same set of
Thus (d) is correct option. chromosomes as those of the parent cell.
(c) half the amount of DNA and the same set of
15. Which of the following options are the pyrimidine
chromosomes as those of the parent cell.
bases found in DNA?
(d) double the amount of DNA and a set of
(a) Uracil and Thymine
chromosomes different from those of the
(b) Thymine and Cytosine
parent cell.
(c) Adenine and Thymine
(d) Cytosine and Uracil Ans : SQP 2008

Ans : SQP 2020 Thus (b) is correct option.

The pyrimidine bases present in the DNA are 19. Abnormal and uncontrolled mitosis in an organ
cytosine and thymine. Apart from the pyrimidine will result in:
bases, purine bases are also present — adenine (a) gamete (b) Zygote
and guanine. (c) Cancer (d) None of these
Thus (b) is correct option.
Ans : MAIN 2010
16. Chromosomes and genes both play a crucial Cancer is a group of diseases characterized by
role in inheritance and cellular function. During uncontrolled cell division —mitosis.
cell division, they ensure the transfer of genetic Thus (c) is correct option.
information to daughter cells, maintaining
consistency across generations Which statement 20. Meiotic division occurs in
is true of both chromosomes and genes? (a) vegetative cells
(a) Each codes for a specific protein. (b) reproductive cells
(b) Each may be copied and passed on in mitosis. (c) meristematic cells
(c) Each may be either dominant or recessive. (d) none of these.
(d) Each may exist as two or more alleles.
Ans : SQP 2016
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 11

The meiotic division takes place in the reproductive Ans : SQP 2017

cells. Metaphase is the best time to count and study

Thus (b) is correct option. the number and morphology of chromosomes.
Thus (d) is correct option.
21. Identify the wrong statement about meiosis:
(a) Pairing of homologous chromosomes. 25. Which of the following bonds are broken during
(b) Four haploid cells are formed. DNA replication?
(c) At the end of meiosis the number of (a) Hydrogen bonds between bases.
chromosomes are reduced to half. (b) Phosphodiester bonds.
(d) Two cycle of DNA replication occurs. (c) Covalent bonds between bases.
Ans : MAIN 2003
(d) Ionic bonds between bases and phosphate
groups.
S phase (Synthesis Phase) is the phase of the
cell cycle in which DNA is replicated, occurring Ans : MAIN 2022

between G1 phase and G2 phase. During DNA replication, the hydrogen bonds
Thus (d) is correct option. must be broken between the complementary
nitrogenous bases in the DNA double helix. Once
22. What defines a diploid nucleus? this is accomplished, either side of the DNA
(a) A nucleus containing two unpaired molecule can act as a template to produce another
chromosomes. double stranded DNA molecule.
(b) A nucleus with two alternative forms of a Thus (a) is correct option.
gene.
(c) A nucleus with two separate threads of DNA. 26. Which of the following is incorrect regarding
(d) Anucleus containing two sets of chromosomes. structure of DNA?
Ans : SQP 2008
(i) Nucleotide is composed of pentose sugar,
nitrogenous bases and phosphate group.
A diploid nucleus describes a cell, nucleus, or (ii) Adenine pairs with Thymine and Guanine
organism containing two sets of chromosomes pairs with Cytosine.
(2n). (iii) A = T, C = G
Thus (d) is correct option. (iv) DNA strand winds around the nucleosome,
which consists of eight pairs of histone
23. When a cell divides, these events occur. proteins.
(i) The DNA inside the cell is duplicated exactly. (v) Genes are the fundamental unit of DNA.
(ii) Daughter cells are produced with the same (a) (ii) and (iii) only (b) (i), (ii), (v) only
chromosome number as the parent cell. (c) (iii) and (iv) only (d) None of them
Which type of division has occurred?
(a) Meiosis producing genetically different cells. Ans : COMP 2020

(b) Meiosis producing genetically identical cells. The bases on the opposite strands are connected
(c) Mitosis producing genetically different cells. through hydrogen bonds forming base pairs
(d) Mitosis producing genetically identical cells. (bp). Adenine always forms two hydrogen bonds
Ans : COMP 2001 with thymine from the opposite strand and vice-
versa. Guanine forms three hydrogen bonds with
During mitosis, the following events takes place: cytosine from the opposite strand and vice-versa.
(i) The DNA inside the cell is duplicated exactly. A nucleosome is a section of DNA that is wrapped
(ii) Daughter cells are produced with the same around a core of proteins. Thus, option (iii) and
chromosome number as the parent cell. (iv) are incorrect.
Thus (d) is correct option. Thus (c) is correct option.

24. If you are provided with root-tips of onion in your 27. How does a haploid nucleus differ from a diploid
class and are asked to count the chromosomes nucleus of the same species?
which of the following stages can you most (a) It has different genes.
conveniently look into: (b) It has fewer chromosomes.
(a) Prophase (b) Anaphase (c) It has more alleles.
(c) Telophase (d) Metaphase (d) It is the result of fertilisation.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES
Ans : MAIN 2023
31. The two chromatids of a metaphase chromosome
The haploid nucleus has half the chromosomes represent:
present in a diploid nucleus. (a) Homologous chromosome of a diploid set.
Thus (b) is correct option. (b) Replicated chromosomes to be separated at
anaphase.
28. Which of these structures, involved in cell (c) Non-homologous chromosomes joined at the
division, is present in animal cells but not higher centromere.
plant cells? (d) Matemal and paternal chromosomes joined at
(a) Centriole the centromere.
(b) Centromere
(c) Chromatid Ans : COMP 2013

(d) Chromosome A chromosome consists of two sister chromatids

joined at the centromere. In the anaphase stage,
Ans : SQP 2018
the centromere splits and the two sister chromatids
Paired organelles called centrioles, typically found move to opposite poles.
together near the nucleus in the centrosome, exist Thus (b) is correct option.
primarily in animal cells and serve to control
spindle fibre formation and which later has an 32. Select the correct statement about G 1 phase:
effect on chromosome separation. Centrioles are (a) Cell is metabolically inactive.
absent from the cells of higher plants. (b) DNA in the cell does not replicate.
Thus (a) is correct option. (c) It is not a phase of synthesis of macromolecules.
(d) Cell stops growing.
29. Chromosomes get aligned at the centre of the cell
during : Ans : MAIN 2007

(a) Metaphase The G1 phase is the first of four phases of the cell
(b) Anaphase cycle that takes place in eukaryotic cell division.
(c) Prophase In this part of interphase, the cell synthesizes m
(d) Telophase RNA and proteins in preparation for subsequent
steps leading to mitosis. DNA in the cell replicates
Ans : MAIN 2014
in the S-phase.
During metaphase, the cell's chromosomes align Thus (b) is correct option.
themselves in the middle of the cell through a
type of cellular "tug of war." The chromosomes, 33. Cytokinesis is the division of
which have been replicated and remain joined at (a) nucleus (b) cytoplasm
a central point called the centromere, are called (c) nucleoplasm (d) none of these.
sister chromatids. Ans : SQP 2016
Thus (a) is correct option.
Cytokinesis is the physical process of cell division,
30. What is produced when a cell undergoes mitosis which divides the cytoplasm of a parental cell into
once? two daughter cells. It occurs concurrently with
(a) Four new cells which are different from each two types of nuclear division called mitosis and
other and from their parent cell. meiosis, which occur in animal cells.
(b) Four new cells which are identical to each Thus (b) is correct option.
other and to their parent cell.
(c) Two new cells which are different from each 34. Cell division by meiosis of a parent cell with 23
other and from their parent cell. pairs of chromosomes will result in:
(d) Two new cells which are identical to each (a) 2 cells, each with 23 pairs of chromosomes.
other and to their parent cell. (b) 2 cells, each with 23 single chromosomes.
(c) 4 cells, each with 23 pairs of chromosomes.
Ans : SQP 2018
(d) 4 cells, each with 23 single chromosomes.
A cell undergoes mitosis to produce two (daughter) Ans : COMP 2023
cells that are genetically identical to the original
(parent) cell. In meiosis the parent cell divides twice to form
Thus (d) is correct option. four cells, each with a single set of chromosomes
(haploid).
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 13

This means the chromosome number will be daughter cells, each containing the same number
halved to 23 single chromosomes. and kind of chromosomes as the mother cell.
Thus (d) is correct option. Thus (d) is correct option.

35. How many mitotic divisions of a meristematic cell 39. Which of the following might you find in the
in a root tip are needed to produce 256 daughter backbone of DNA?
cells? 1. Phosphate group
(a) 8 (b) 16 2. Hexose sugar
(c) 32 (d) 64 3. Adenine
(a) 1, 2 and 3 (b) 1 only
Ans : SQP 2002
(c) 2 only (d) 1 and 2
Every mitotic division will lead to the formation
of twice the number of mother cells, hence to form Ans : SQP 2002

256 cells from a root tip cell, 8 generations of The backbone of a DNA molecule consists of the
mitotic divisions must occur (28 = 256 cells). phosphate groups and the deoxyribose sugars,
Thus (a) is correct option. whereas the base region of the DNA molecule
consists of the nitrogenous bases; therefore, the
36. Equatorial plane is formed in: backbone of DNA is made up of phosphate groups
(a) Anaphase (b) Metaphase and pentose sugars. Adenine is part of the base
(c) Telophase (d) Interphase region of the molecule. DNA does not contain any
Ans : COMP 2009 hexose (six-carbon) sugars.
Thus (b) is correct option.
During metaphase, all the chromosomes are
aligned on a plane called the metaphase plate, 40. At which stage in mitosis and meiosis do
or the equatorial plane, midway between the two chromosomes always line up at the equator of the
poles of the cell. spindle?
Thus (b) is correct option. (a) Prophase (b) Telophase
(c) Anaphase (d) Metaphase
37. During Telophase, the
(a) nuclear membrane is formed Ans : SQP 2014
(b) nucleolus appears During metaphase, spindle fibers attach to the
(c) astral rays disappear centromere of each pair of sister chromatids. The
(d) all of these sister chromatids line up at the equator, or center,
Ans : SQP 2001 of the cell.
Thus (d) is correct option.
During telophase, a nuclear membrane forms
around each set of chromosomes to separate 41. Which statement describes human cells formed by
the nuclear DNA from the cytoplasm. The meiosis?
chromosomes begin to uncoil, which makes them (a) They are genetically identical and they
diffuse and less compact. become gametes.
Thus (d) is correct option. (b) They are genetically identical and they
become tissues.
38. The following features are shown by the dividing
(c) They are not genetically identical and they
cell in a stage of mitosis: the nuclear membrane
become gametes.
reappears; spindle fibres disappear; chromatids
(d) They are not genetically identical and they
become thin; daughter nuclei are formed. Which
become tissues.
stage is being discussed here?
(a) Prophase (b) Metaphase Ans : MAIN 2012
(c) Anaphase (d) Telophase In meiosis, the parent cell divides twice to form
Ans : MAIN 2010 four cells, each with a single set of chromosomes
(haploid).The gametes produced by meiosis are
During telophase, the chromosomes begin to
not identical because recombination of alleles
decondense, the spindle breaks down, and the
(genes) present on two homologous chromosomes
nuclear membranes and nucleoli re-form. The
occurs during meiosis.
cytoplasm of the mother cell divides to form two
Thus (c) is correct option.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

42. Which of the following cellular structures always or gametes. Meiosis create genetic variation by
disappears during mitosis and meiosis? making new combinations of gene variants.
(a) Plasma membrane Thus (c) is correct option.
(b) Nucleolus and nuclear envelope
(c) Plastids 46. Duplicated chromosomes are joined at a point
(d) None of these termed:
(a) Centrosome (b) Centromere
Ans : SQP 2015
(c) Centriole (d) Chromatid
The cellular structure that disappears during Ans : COMP 2013
mitosis is nuclear membrane and nucleolus. The
cell then divides by cytokinesis to produce two The centromere is the region where two sister
genetically identical daughter cells. So, the correct chromatids are connected in a duplicated
answer is ‘Nuclear membrane and nucleolus’. chromosome, ensuring correct attachment to
spindle fibers during cell division.
Thus (b) is correct option.
Thus (b) is correct option.
43. A cell has five pairs of chromosomes. After
47. What is not a function of meiosis?
mitotic division, the number of chromosomes in
(a) Producing genetically different cells
the daughter cells will be:
(b) Producing nuclei in ovules
(a) Five (b) Ten
(c) Producing sperm cells
(c) Twenty (d) Forty
(d) Repairing damaged tissues
Ans : SQP 2006
Ans : COMP 2002
The movement of chromatids is carried out by
Repairing damaged tissues is the function of
spindle fibers. If the cell has 5 chromosomes,
mitosis.
during the S-phase it replicates. So, the number
Thus (d) is correct option.
of chromosomes entering mitosis will be 10
chromosomes. During anaphase chromosomes 48. A complex consisting of DNA strand and a core of
split into chromatids. histones is ______
Thus (b) is correct option. (a) Nucleotide (b) Nucleosome
(c) Centrosome (d) Chromosome
44. Which phase comes between G1 and G2 phase?
Ans : COMP 2005
(a) G o phase (b) M - phase
(c) S- phase (d) Interphase Nucleosome is a complex structure in which DNA
wraps around a protein core of eight histone
Ans : MAIN 2021
molecules.
The interphase of the cell cycle comprises G1, Thus (b) is correct option.
S and G2 phase. The S-phase separates the two
growth phases. 49. Meiosis ______ the parental chromosome
Thus (c) is correct option. number.
(a) Doubles (b) Reduces
45. Some features of cell division are listed. (c) Maintains (d) Stabilises
(i) Haploid cells are produced
(ii) New cells are genetically identical Ans : SQP 2000

(iii) Reduction division Meiosis is a type of cell division that reduces the
(iv) Results in variation number of chromosomes in the parent cell by half
Which features would be associated with meiosis? and produces four gamete cells.
(a) (i), (ii) and (iii) (b) (i), (ii) and (iv) Thus (b) is correct option.
(c) (i), (iii) and (iv) (d) (ii), (iii) and (iv)
50. ______ occupies the longest “period in a cell
Ans : SQP 2018
cycle.
During meiosis a diploid cell divides twice to form (a) Interphase (b) Prophase
four daughter cells. These four daughter cells have (c) Metaphase (d) Telophase
half the number of chromosomes of the parent
Ans : MAIN 2009
cell they are haploid. Meiosis produces sex cells
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 15

During interphase, the cell undergoes normal (a) (i) - (B), (ii) - (C), (iii) - (D), (iv) - (A)
growth processes while also preparing for cell (b) (i) - (D), (ii) - (A), (iii) - (B), (iv) - (C)
division. It is the longest phase of the cell cycle, (c) (i) - (B), (ii) - (A), (iii) - (D), (iv) - (C)
cell spends approximately 90% of its time in this (d) (i) - (D), (ii) - (A), (iii) - (C), (iv) - (B)
phase.
Ans : SQP 2014
Thus (a) is correct option.
In metaphase, chromosomes get arranged in
51. Synthesis phase in the cell cycle is called so, a horizontal plane at the equator. Daughter
because of the synthesis of more ______ chromosomes move to the opposite poles of a
(a) RNA (b) RNA and Proteins spindle in anaphase.
(c) DNA (d) Glucose Chromosomes become visible as fine long
Ans : COMP 2011
threads in prophase Chromosomes lose their
distinctiveness and gradually become transformed
Before the start of karyokinesis, DNA duplication into a chromatin network in telophase.
or semi-conservative replication occurs during the Thus (b) is correct option.
synthesis phase of interphase.
Thus (c) is correct option. 54. Chrosomes get aligned at the centre of the cell
during ______
52. The cell component visible only during cell (a) Metaphase (b) Anaphase
division: (c) Prophase (d) Telophase
(a) Chromosome (b) Chromoplast
Ans : COMP 2022
(c) hromatin (d) Centriole
During metaphase, each chromosome gets
Ans : MAIN 2018
attached to the spindle by its centromere.
The cell component visible only during cell division The chromosomes line up in the centre at the
is chromosome. In a non-dividing cell, DNA is equatorial plane.
present as chromatin fibres. Chromosomes are Thus (a) is correct option.
formed by coiling and supercoiling of chromatin
fibres. Since, during cell division, chromosomes 55. The type of cell division that leads to the formation
are highly condensed, they are visible under light of two identical daughter cells is ______
microscope. (a) Mitosis
Thus (a) is correct option. (b) Genetic recombination
(c) Meiosis
53. Match the events given in Column A with the (d) Cytokinesis
phase in mitotic cell division in Column B and
Ans : SQP 2021
select the correct option.
Mitosis is a process of nuclear division in
Column A Column B eukaryotic cells that occurs when a parent cell
(i) Chromosomes (A) Anaphase divides to produce two identical daughter cells.
get arranged in a Thus (a) is correct option.
horizontal plane at the
56. G1, S and G2 are phases present in______.
equator.
(a) prophase (b) interphase
(ii) Daughter chromosomes (B) Prophase
(c) metaphase (d) anaphase.
move to the opposite
poles of a spindle. Ans : MAIN 2001

(iii) Chromosomes become (C) Telophase A typical cell cycle comprises of interphase
visible as fine long and mitosis. Interphase comprises of G1 or first
threads growth phase, Synthesis or S phase and second
growth phase or G2 phase. G1 phase starts after
(iv) Chromosomes lose (D) Metaphase
cytokinesis, S phase starts after G1 phase and is
their distinctiveness
followed by second growth phase or G2 phase.
and gradually become
Thus (b) is correct option.
transformed into a
chromatin network
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CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

DIRECTION : Complete the following statements 61. The exchange of chromatid parts between the
with appropriate option . maternal and the patemal chromatids of a pair
of a homologous chromosomes during meiosis is
57. DNA content doubles during ______ ______
(a) Interphase (b) Prophase (a) Crossing over
(c) Metaphase (d) Growth phase (b) Karyokinesis
(c) Meiosis
Ans : COMP 2012
(d) Cytokinesis
During a mitotic cell cycle, the DNA content
Ans : MAIN 2002
per chromosome doubles during S phase (each
chromosome starts as one chromatid, then Crossing over or recombination is the exchange
becomes a pair of identical sister chromatids of chromosome segments between non-sister
during S phase), but the chromosome number chromatids in meiosis. Crossing over creates new
stays the same. combinations of genes in the gametes that are not
Thus (a) is correct option. found in either parent, contributing to genetic
diversity.
58. The disappearance of spindle and uncoiling of Thus (a) is correct option.
chromosomes takes place in:
(a) Anaphase (b) Telophase 62. ______ is not a stage of mitosis.
(c) Pachytene (d) Meiosis (a) prophase (b) Interphase
(c) Metaphase (d) Anaphase
Ans : SQP 2018
Ans : COMP 2010
Telophase is the fifth and final phase of mitosis.
During telophase, the chromosomes begin to Interphase is technically not part of mitosis, but
uncoil, the spindle breaks down, and the nuclear rather encompasses stages G1, S, and G2 of the
membranes and nucleoli reform. The cytoplasm cell cycle. In interphase, the cell is engaged in
of the mother cell divides to form two daughter metabolic activity and prepares for mitosis.
cells, each containing the same number and kind Thus (b) is correct option.
of chromosomes as the mother cell.
Thus (b) is correct option. 63. The period between two successive mitotic
divisions is :
59. A duplicated chromosome has ______ (a) Diakinesis (b) Interphase
chromatids (c) Anaphase (d) Mitosis
(a) One (b) Two Ans : SQP 2004
(c) Three (d) Four
The period between two successive mitotic
Ans : COMP 2004 divisions is interphase. It is also called resting
A single part of the duplicated chromosome is phase and includes all the changes that takes
known as the chromatid which is separated during place in a newly formed cell before it becomes
the cell division and each cell gets one chromatid. capable of division.
Thus, the duplicated chromosome has two sister Thus (b) is correct option.
chromatids.
Thus (b) is correct option. 64. Lateral pairing of homologous chromosomes is
known as ______
60. Mitosis is characterised by ______ (a) Recombination (b) Chiasmata
(a) Reduction division (c) Cross over (d) Synapsis
(b) Equal division Ans : COMP 2007
(c) Both reduction and equal division
(d) Pairing of homologous chromosomes Synapsis is the pairing of two chromosomes that
occurs during meiosis. It allows matching-up of
Ans : SQP 2009 homologous pairs prior to their segregation and
Mitosis is characterised by equal division because possible chromosomal crossover between them.
the chromosome number in the daughter cells Synapsis takes place during prophase I of meiosis.
remain same as that of parent cell. Thus (d) is correct option.
Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 17

65. The period of rest between two successive cell of gametes through reductional division which
divisions is ______ result in halving of the number of chromosomes.
(a) Karyokinesis Meiosis results in the formation of gametes.
(b) Interphase Thus (d) is correct option.
(c) Prophase
(d) Dikaryophase 69. Centromere is concerned with ______.
(a) Duplication of DNA
Ans : MAIN 2019
(b) Formation of spindle fibres
The period between two successive cell divisions (c) Splitting of chromosomes
is called interphase or the resting phase. (d) Replication of DNA
Thus (b) is correct option. Ans : SQP 2017

66. In complementary base pairing of DNA, guanine A centromere is a region of DNA that is
always pairs with ______ and adenine always responsible for the movement of the replicated
pairs with ______. chromosomes into the two daughter cells by
(a) Cytosine, uracil splitting of chromosomes.
(b) Cytosine, thymine Thus (c) is correct option.
(c) Thymine, cytosine
(d) Guanine, adenine 70. The nuclear membrane disappears completely
during ______
Ans : COMP 2021
(a) Early prophase
The four nitrogenous bases of DNA are thymine, (b) Later prophase
adenine, guanine and cytosine. Guanine and (c) Metaphase
cytosine are bound together by three hydrogen (d) Telophase
bonds; whereas, adenine and thymine are bound Ans : MAIN 2002
together by two hydrogen bonds. This is known as
complementary base pairing. Nuclear membrane starts disappearing at the start
Thus (b) is correct option. of mitosis and by the late prophase it disappears
completely along with the major cell organelles.
67. A pair of corresponding chromosomes of the same Thus (b) is correct option.
shape and size but one from each parent.
(a) Autosomes 71. Network of long, thin, dark staining fibres seen in
(b) Sex chromosomes the interphase nucleus is ______
(c) Homologous chromosomes (a) Synapsis
(d) Analogous chromosomes (b) Chromatin fibres
(c) Nucleosome
Ans : SQP 2002
(d) Nucleotide
Homologous chromosomes are a pair of Ans : SQP 2006
corresponding chromosomes of the same shape,
size and length containing the same genes in In inter-phase, the nucleus shows a network of
the same order, one from each parent. During very long extremely thin dark staining fibres
fertilisation if pairing between sex chromosomes called as chromatin fibres. Chromosomes are the
of same shape and size occurs such pairing is high condensed coiled chromatin fibres.
called homologous pairing and chromosomes are Thus (b) is correct option.
called homologous chromosomes.
72. Cells which are not dividing are likely to be at
Thus (c) is correct option.
______
68. Meiosis in diploid organisms results in ______ (a) G 1 (b) G 2
(a) Production of gametes (c) G o (d) S phase
(b) Reduction in the number of chromosomes Ans : COMP 2012
(c) Introduction of variation
Cells that do not divide further exit G 1 phase to
(d) All of the above
enter an inactive stage and called quiescent stage
Ans : MAIN 2008 G o of the cell cycle.
Meiosis is cell division responsible for production Thus (c) is correct option.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

73. Spindle Fibres description?

(a) Helps to divide the nucleus equally in the
daughter cells from the parent cell.
(b) Helps to divide the cytoplasm in the daughter
cells from the parent cell.
(c) Helps to divide the chromosome equally in
the daughter cells from the parent cell.
(d) Helps to divide the centrosome equally in the
daughter cells from the parent cell.
Ans : SQP 2005
(a) Anaphase, as chromatids are being pulled
Spindle fibres helps to divide the chromosome towards the opposite poles.
equally in the daughter cells from the parent cell (b) Metaphase, as chromosomes are in the
during both types of nuclear division: mitosis and equatorial plane.
meiosis. (c) Anaphase, as chromosome gets attached to
Thus (c) is correct option. spindle by its centromere.
74. Given below is a diagram representing a stage (d) Telophase, as the chromatids has reached the
during the mitotic cell division. Which one of the two poles.
following option is the correct stage? Ans : SQP 2004

During anaphase the centromeres divide and the

chromatids start moving towards the two opposite
poles.
Thus (a) is correct option.

77. Chromosomes
(a) Thread-like structure found in DNA that
carry genetic information of an organism in
the form of genes.
(a) Prophase (b) Metaphase (b) Ring-like structure found in RNA that carry
(c) Anaphase (d) Telophase genetic information of an organism in the
Ans : SQP 2001
form of genes.
(c) Thread-like structure found in both DNA
During telophase, Chromosome sets assemble and RNA that carry genetic information of
at opposite poles, a nuclear envelope reforms an organism in the form of genes.
around each set and cytokinesis (division of the (d) Thread-like structure found in RNA that
cytoplasm) usually follows. carry genetic information of an organism in
Thus (d) is correct option. the form of genes.
75. Ribosomes Ans : SQP 2014
(a) Scattered inside the cell Chromosomes are thread-like structure found in
(b) Scattered inside the plasma membrane DNA that carry genetic information of an organism
(c) Scattered inside the nucleus in the form of genes. Different organisms have
(d) Scattered in the cytoplasm different numbers of chromosomes. Humans have
Ans : MAIN 2007 23 pairs of chromosomes–22 pairs of numbered
chromosomes, called autosomes, and one pair of
Ribosomes are small granules which are found
sex chromosomes, X and Y.
scattered in the cytoplasm. They are single walled
Thus (a) is correct option.
spherical bodies composed mainly of RNA.
Thus (d) is correct option. 78. Chromosomes
(a) The carriers of heredity
76. Given below is a diagram representing a stage
(b) The controlling centre of the cell
during the mitotic cell division. Which one of the
(c) The site for various chemical reactions
following option is the correct stage as per the
(d) Intracellular digestion.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 19
Ans : SQP 2023
They give instructions for a living being to make
Chromosomes are the carriers of heredity which molecules called proteins. In other words, they
means they are responsible to provide hereditary encode particular protein which express in the
characteristics and genetic information to the form of some particular feature of the body.
various cells. Thus (c) is correct option.
Thus (a) is correct option.
83. Nucleus
79. Spindle fibres (a) Centre of the cytoplasm
(a) Between the two centrioles (b) Between the cell membrane and cytoplasm
(b) Between the two centrosomes (c) Equator of the cell
(c) Between chromatid and centromere (d) Between nucleolus and cell membrane
(d) Between two centromeres
Ans : COMP 2010
Ans : MAIN 2018
Nucleus is a large spherical body found at the
They appear between the two daughter centrioles centre of the cytoplasm. It regulates all the cell
and is necessary to equally divide the chromosomes function.
in a parental cell into two daughter cells during Thus (a) is correct option.
both types of nuclear division mitosis and meiosis.
Thus (a) is correct option. 84. Centromeres.
(a) It is a part of nucleus through which
80. Cytoplasm. chromosomes are linked.
(a) Inside the cell between the nucleolus and the (b) It is a part of chromosome through which
centromere chromatids are linked.
(b) Inside the cell between the nucleus and the (c) It is a part of DNA through which chromatids
cell membrane are linked.
(c) Inside the cell between the mitochondria and (d) It is a part of RNA through which
the cell membrane. chromosomes are linked.
(d) Inside the cell near to the cell membrane
Ans : COMP 2006
Ans : MAIN 2001
Centromere is a structure in a chromosome that
Cytoplasm is located inside the cell between the holds together the two chromatids (the daughter
nucleus and the cell membrane. It comprises gel- strands of a replicated chromosome).
like substance called cytosol and the various cell Thus (b) is correct option.
organelles (the cell’s internal sub-structures).
Thus (b) is correct option. 85. Meiosis
(a) A process where a single cell divides twice to
81. Chromosomes produce four cells containing half the original
(a) In the cytoplasm of plant and animal cell. amount of genetic information.
(b) In the centrosome of plant and animal cell. (b) A process where a nucleus divides twice to
(c) In the RNA of plant and animal cell. produce four cells containing the original
(d) In the nucleus of plant and animal cell. amount of genetic information.
(c) A process where a cell divides thrice to
Ans : COMP 2010
produce four cells containing half the original
Chromosomes are thread like structures located amount of genetic information.
inside the nucleus of animal and plant cells. Each (d) A process where a DNA divides twice to
chromosome is made of protein and a single produce eight cells containing half the original
molecule of deoxyribonucleic acid (DNA). amount of genetic information.
Thus (d) is correct option.
Ans : MAIN 2020
82. Genes Meiosis is a process where a single cell divides
(a) Help in carrying gametes twice to produce four cells containing half the
(b) Encode fats and lipids original amount of genetic information. These
(c) Encode particular protein cells are sex cells i.e., sperms in males and eggs
(d) Help in DNA replication in females.
Ans : MAIN 2007 Thus (a) is correct option.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

86. Gene What is the diploid number for this organism?

(a) Physical and functional unit of heredity that (a) 10 (b) 20
carries DNA material from one generation to (c) 40 (d) 46
the next.
Ans : COMP 2017
(b) Physical and functional unit of heredity that
carries chromosomes from one generation to The haploid number is exactly half the total
the next. number of chromosomes present in the organism’s
(c) Physical and functional unit of heredity that somatic cells and results due to reduction division
carries gametes from one generation to the next. (meiosis). As the nucleus contains 20 chromosomes
(d) Physical and functional unit of heredity the diploid number will be twice that of the
that carries genetic information from one haploid cell, i.e., 40.
generation to the next. Thus (c) is correct option.

Ans : COMP 2022 89. In the following diagram of a section of a DNA

The fundamental unit of heredity that carries molecule, what is the part labelled Q?
genetic information from one generation to the next.
A gene is an ordered sequence of nucleotides located
on a particular position on a particular chromosome
that encodes a specific functional protein.
Thus (d) is correct option.

87. Mitosis
(a) A process of cell replication during which one
cell gives rise to two non-identical daughter cells.
(b) A process of fission of cell during which one
cell gives rise to three genetically identical
daughter cells.
(c) A process of nuclear division during which
one cell gives rise to two genetically identical
daughter cells.
(d) A process of cell division during which one
cell gives rise to four genetically identical
(a) Adenine (b) Cytosine
daughter cells.
(c) Thymine (d) Uracil
Ans : MAIN 2000
Ans : SQP 2001
Mitosis, a process of nuclear division during which
In base pairing, adenine always pairs with
one cell gives rise to two genetically identical
thymine, and guanine always pairs with cytosine.
daughter cells. It has four stages prophase,
Thus (b) is correct option.
metaphase, anaphase and telophase.
Thus (c) is correct option. 90. The diagram given below represents a stage during
cell division. Which stage is depicted and name
88. The diagram shows a cell of an organism formed
the stage that comes before the stage shown?
by reduction division. The nucleus contains 20
chromosomes
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 21

(a) Metaphase, Prophase enzymes, hormones etc.

(b) Metaphase, Anaphase Thus (b) is correct option.
(c) Anaphase, Metaphase
(d) Anaphase, Telophase 93. DNA
(a) Controls functioning of RNA
Ans : SQP 2009
(b) Controls biosynthetic processes of cell.
Metaphase is marked by the arrangement of (c) Stores all of the genetic information
chromosomes on the equator of spindle. Prophase (d) Controls mitotic and meiotic division.
is the stage which comes before Metaphase. Ans : MAIN 2010
Thus (a) is correct option.
The function of DNA is to store all of the genetic
91. The diagram shows the formation of new diploid information that an organism needs to develop,
cells. function and reproduce.
Thus (c) is correct option.

94. The diagram shows a cell of an organism. The

nucleus contains 12 chromosomes.

What do arrows X and Y represent?

X Y
After it divides by mitosis, how many chromosomes
(a) Duplication of merosis
would be present in one of the daughter cells?
chromosomes
(a) 6 (b) 12
(b) Duplication of merosis (c) 18 (d) 24
chromosomes
Ans : COMP 2007
(c) Meiosis duplication of
During mitosis, a cell duplicates all of its contents,
chromosomes
including its chromosomes, and splits to form two
(d) Mitosis duplication of identical daughter cells with the same number of
chromosomes chromosomes.
At the end of mitosis, the two daughter cells will
Ans : COMP 2013
be exact copies of the original cell. Each daughter
In mitosis, chromosome duplication occurs during cell will have 12 chromosomes.
interphase. Mitosis is a part of the cell cycle in Thus (b) is correct option.
which replicated chromosomes are separated into
two new nuclei. 95. The diagram shows stages of meiosis in a human
Thus (b) is correct option. testis:

92. Golgi Apparatus

(a) Synthesis of respiratory enzymes
(b) Synthesis and secretion of enzymes, hormones
etc.
(c) Synthesis of Protein.
(d) Regulates cell function
Ans : SQP 2017

Golgi apparatus are stacks of flattened membrane

sacs that helps in the synthesis and secretion of
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

After meiosis I After meiosis II

(a) 46 46
(b) 46 23
(c) 23 46
(d) 23 23

Ans : SQP 2015

A human cell has 46 total or 23 pairs of

chromosomes. The first division is called the
reduction division or meiosis
I — because it reduces the number of chromosomes
from 46 chromosomes or 2n to 23 chromosomes
or n. Meiosis II resembles a mitotic division, and
after meiosis II, 23 chromosomes results.
Thus (d) is correct option.

96. In the diagram given below of a section of a DNA

molecule, which are the two components of part X?

(a) Ribose and Phosphate

(b) Guanine and Phosphate
(c) Deoxyribose and Thymine
Ans : MAIN 2000
(d) Deoxyribose and Phosphate
The DNA in the cell is copied in preparation for
Ans : COMP 2009
cell division during interphase or a stage before
The backbone of a DNA molecule consists of the the start of mitosis. This results in two identical
phosphate groups and the deoxyribose sugars, full sets of chromosomes.
whereas the base region of the DNA molecule Thus (a) is correct option.
consists of the nitrogenous bases; therefore, the
backbone of DNA is made up of phosphate groups
and pentose sugars. Adenine is part of the base
region of the molecule. DNA does not contain any ASSERTION AND REASON
hexose (six-carbon) sugars.
Thus (d) is correct option.
98. Assertion : G1 phase is the interval between
97. The diagram shows a cell before and during mitosis and initiation of DNA replication.
mitosis. At which stage are the chromosomes Reason : The cell is metabolically inactive during
copied? G1 phase.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 23

(a) If both assertion and reason are true and are formed which remain attached in pairs and
reason is the correct explanation of assertion. the number of chromosomes does not increase. As
(b) If both assertion and reason are true, but the chromatin fibres are elongated chromosomes,
reason is not the correct explanation of each chromosome comes to have two chromatin
assertion. threads which are attached at centromere. During
(c) If assertion is true but reason is false. metaphase, every chromosome has two chromatids
(d) If both Assertion and Reason are false. which separate from each other during anaphase.
Thus (a) is correct option.
Ans : SQP 2014

G1 phase is also known as first growth phase 101. Assertion : During anaphase, centromere of each
or post mitotic gap phase. It is the phase chromosomes splits and chromatids separate.
between end of mitotic phase of previous cell Reason : Chromatids move to opposite poles.
and initiation of S-phase of next mitotic phase. (a) If both assertion and reason are true and
During G1 phase, the cell is metabolically active reason is the correct explanation of assertion.
and continuously grows. RNA and proteins are (b) If both assertion and reason are true, but
synthesized. Organelle duplication such as those reason is not the correct explanation of
of mitochondria and chloroplast also occurs assertion.
during this phase. (c) If assertion is true but reason is false.
Thus (c) is correct option. (d) If both Assertion and Reason are false.

99. Assertion : The M phase represents the phase Ans : SQP 2012

when the actual cell division occurs. During anaphase the centromeres divide and
Reason : Interphase represents the phase between the chromatids start moving towards the two
two successive M Phase. opposite poles. Spindle fibres attached to the
(a) If both assertion and reason are true and centromeres shorten and pull the chromosomes;
reason is the correct explanation of assertion. the centromeres lead the path while the limbs trail
(b) If both assertion and reason are true, but behind. Anaphase ensures that each chromosome
reason is not the correct explanation of receives identical copies of the parent cell’s DNA.
assertion. Thus (b) is correct option.
(c) If assertion is true but reason is false.
(d) If both Assertion and Reason are false. 102. Assertion : Mitosis maintains the genetic similarity
of somatic cells.
Ans : COMP 2019
Reason : Chromosomes do not undergo crossing
The M phase represents the phase when the over.
actual cell division occurs. Interphase represents (a) If both assertion and reason are true and
the phase between two successive phases. reason is the correct explanation of assertion.
Thus (b) is correct option. (b) If both assertion and reason are true, but
reason is not the correct explanation of
100. Assertion : Every chromosome, during metaphase
assertion.
has two chromatids.
(c) If assertion is true but reason is false.
Reason : Synthesis of DNA takes places in the
(d) If both Assertion and Reason are false.
S-phase of interphase.
(a) If both assertion and reason are true and Ans : SQP 2017

reason is the correct explanation of assertion. Mitosis keeps all the somatic cells of an organism
(b) If both assertion and reason are true, but genetically similar, resembling the fertilized
reason is not the correct explanation of egg. Mitosis involves replication and equitable
assertion. distribution of all the chromosomes so that all the
(c) If assertion is true but reason is false. cells of a multicellular organism have the same
(d) If both Assertion and Reason are false. number and type of chromosomes.
Ans : MAIN 2022 During the formation of gametes by meiosis,
paired chromosomes from each parent align so
In S phase or synthesis phase, chromosomes
that similar DNA sequences from the paired
replicates, DNA content doubles, i.e., 1C to 2C for
chromosomes cross over one another. Crossing
haploid cells and 2C to 4C for diploid cells. Along
over results in a shuffling of genetic material and
with replication of DNA, new chromatin fibres
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

is an important cause of the genetic variation seen Reason: Interphase (I-phase) is the long non-
among offspring. dividing phase.
Thus (a) is correct option. (a) If both assertion and reason are true and
reason is the correct explanation of assertion.
103. Assertion : In animal cells, cytokinesis is (b) If both assertion and reason are true, but
marked by the appearance of a furrow in plasma reason is not the correct explanation of
membrane. assertion.
Reason : In plant cells, the formation of the (c) If assertion is true but reason is false.
new cell wall starts with the formation of simple (d) If both Assertion and Reason are false.
precursor called cell Plate.
(a) If both assertion and reason are true and Ans : SQP 2011

reason is the correct explanation of assertion. The cell cycle is divided into two basic phase:
(b) If both assertion and reason are true, but (i) interphase, (ii) M-phase.
reason is not the correct explanation of The M phase represents the phase when the actual
assertion. cell division or mitosis occurs and the interphase
(c) If assertion is true but reason is false. represents the phase between two successive M
(d) If both Assertion and Reason are false. phases. In the 24 hour average duration of cell
Ans : SQP 2004
cycle of human cell, cell division proper lasts for
only about an hour. The interphase lasts more
In an animal cell, cytokinesis is marked by the than 95% of the duration of cell cycle during
appearance of a furrow in the plasma membrane which the cell grows and DNA is replicated.
which gradually deepens and ultimately joins in Thus (b) is correct option.
the centre dividing the cell cytoplasm into two.
As plants cells are enclosed by a relatively 106. Assertion : Karyokinesis occurs in M-phase.
inextensible cell wall they undergo cytokinesis by Reason : Cell division stops in M-phase.
a different mechanism. New cell plates are formed (a) If both assertion and reason are true and
at the equator, which extend from centre to the reason is the correct explanation of assertion.
periphery (centrifugal) until the cell divides into (b) If both assertion and reason are true, but
two daughter cells. reason is not the correct explanation of
Thus (b) is correct option. assertion.
(c) If assertion is true but reason is false.
104. Assertion: Genes are specific sequences of (d) If both Assertion and Reason are false.
nucleotides on a chromosome.
Reason: A nucleotide is made up of nitrogenous Ans : MAIN 2007

base, a phosphate group and a pentose sugar. M-phase represents the phase of actual division.
(a) If both assertion and reason are true and It consists of karyokinesis (the division of nucleus)
reason is the correct explanation of assertion. followed by cytokinesis (the division of cytoplasm).
(b) If both assertion and reason are true, but Cell division continues throughout the M-phase
reason is not the correct explanation of and after the M-phase is completed cell division
assertion. ceases (stops).
(c) If assertion is true but reason is false. Thus (d) is correct option.
(d) If both Assertion and Reason are false.
Ans : MAIN 2016

Genes are made up of DNA and each chromosome

contains many genes. Genes are specific sequences ONE MARK QUESTIONS
of nucleotides on a chromosome. A nucleotide has
three components: a nitrogenous base, a pentose
sugar (deoxyribose for DNA), and a phosphate DIRECTION : Name the following :
group.
Thus (b) is correct option. 107. Acts as bearer of heredity units.
105. Assertion: Interphase occupies 75-95% of the Ans : MAIN 2002
total generation time. Chromosomes
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 25

108. A pair of corresponding chromosomes of the same Mitosis

shape and size and derived one from each parent.
118. The stage when sister chromosomes separate from
Ans : SQP 2018, 2017
the paired condition.
Homologous Chromosome Ans : SQP 2005

109. The number of chromosomes present in a nerve Meiosis

cell of a human being.
119. The structure which initiates cell division in
Ans : COMP 2018
animal cells.
46 Ans : MAIN 2001

110. A region of plant body where cell division occurs Centrosome

very actively.
120. The point at which the duplicated chromosomes
Ans : SQP 2002, 1995
are joined.
Growing points (Apical meristem) such as tips of Ans : COMP 2010
root and stems.
Centromere
111. Chromosomes appear thread like.
121. The largest phase of a normal cell cycle.
Ans : COMP 2009
Ans : MAIN 2000
Telophase
Prophase
112. The type of cell division which occurs in the cells
of the reproductive organs. 122. The shortest phase of mitosis.

Ans : MAIN 2010 Ans : COMP 2008

Meiosis Anaphase

113. The exchange of chromatid parts between the 123. The points of attachment where crossing over
maternal and the paternal chromatids of a pair of occurs.
homologous chromosomes during meiosis. Ans : MAIN 2003

Ans : SQP 2016 Chiasmata

Crossing over
124. The type of cell division that occurs in unicellular
114. A nitrogenous base in DNA. organisms.

Ans : MAIN 2022 Ans : SQP 2015

Adenine Amitosis

115. The two kinds of cell division found in living 125. Division of nucleus.
organisms. Ans : MAIN 2009

Ans : COMP 2023 Karyokinesis

Mitosis and Meiosis
126. Division of cytoplasm.
116. Name the stage during which nuclear membrane Ans : COMP 2016
and nucleolus reappear.
Cytokinesis
Ans : SQP 2018
127. The stage when chromosomes arrange at the
Telophase
equator.
117. The kind of division normally seen at the tip of Ans : SQP 2007
root and shoot system.
Metaphase
Ans : MAIN 2014
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

128. A membrane that disappears during late prophase. Ans : SQP 2018

Ans : SQP 2023

nucleus

Nuclear membrane. 138. The direct cell division is called as______.

129. The structure responsible to transmit Ans : COMP 2011

characteristics from parent to offspring. amitosis

Ans : MAIN 2000
139. The chromosome number is______in meiosis.
Chromosome
Ans : MAIN 2003

130. The specific part of a chromosome that determines reduced

hereditary characteristics.
140. The paired homologous chromosomes of the
Ans : COMP 2021
zygotene stage are called______.
DNA
Ans : SQP 2017

131. The kind of cell division which occur in pollen bivalents

grains.
141. The process by which cell multiply is
Ans : MAIN 2012
called______.
Meiosis
Ans : SQP 2004

132. What are chromosomes ? cell division

Ans : SQP 2019
142. In______of interphase, RNA and proteins are
The chromosomes are fine thread like structures synthesised.
found in the nucleus of both plant and animal
Ans : MAIN 2007
cells.
G1 - phase

DIRECTION : Complete the following: 143. Condensation of chromosome with centromere

occurs in______of interphase.
133. The region of the attachment of chromosomes to Ans : MAIN 2001
spindle fibres is at______.
S-phase
Ans : COMP 2014

Centromere DIRECTION : State true/false And if the statement

is false than write the correct statement :
134. Exchange of genetic materials between non-sister
chromatids is called______.
144. Mitosis is the type of cell division occurring in the
Ans : MAIN 2000 cells of injured parts of the body.
crossing over Ans : SQP 2010

135. ______is the pairing of chromosomes during True

zygotene.
145. Lysosomes is a part of the cell in which
Ans : COMP 2008 chromosomes are present.
Synapsis Ans : MAIN 2011

False. Nucleus is a part of cell in which

136. Replication of DNA occurs in the______of chromosomes are present.
interphase.
Ans : MAIN 2020
146. Centromere is the organelle of the cell that
initiates cell division.
S-phase Ans : COMP 2011

137. Karyokinesis is the division of______. True

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 27

147. The points at which crossing over has taken place 156. Choose the correct answer :
between homologous chromosomes are called Duplicated chromosomes are joined at a point
centromere. termed
(centrosome, centromere, centriole, chromatid).
Ans : SQP 2017

False. The points at which crossing over has Ans : MAIN 2002

taken place between homologous chromosomes Centromere

are called chiasma.

148. Mitosis is called reduction division. DIRECTION : Fill in the blanks with suitable words:

Ans : SQP 2010

157. The chromosome number in our skin cell
False. Meiosis is called reduction division. is______.

149. Four daughter cells are formed as a result of Ans : MAIN 2019

meiosis. 46
Ans : COMP 2021
158. The spindle fibres are made-up of______.
True.
Ans : COMP 2015

150. During anaphase, chromosomes are arranged at Microtubules

the equator.
159. The process by which gametes are formed is
Ans : MAIN 2014
called______.
False. During anaphase, chromosomes are
Ans : COMP 2006
arranged at the poles.
Gametogenesis (Meiosis)
151. During telophase, the nuclear membrane
disappears. 160. The direct cell division is called as______.

Ans : COMP 2002 Ans : MAIN 2009

False. During telophase, the nuclear membrane Amitosis

reappears.
161. In meiosis, the parent cell is diploid whereas the
152. The number of pairs of autosomes in man is 22. daughter cell is______.

Ans : MAIN 2000 Ans : COMP 2018

True. Haploid

153. Lysosome is a part of the cell in which chromosomes 162. By the end of prophase, chromosomes are seen as
are present. thick rods each having two rods called______
chromatids.
Ans : SQP 2015
Ans : SQP 2001
False. Nucleus is a part of the cell in which
chromosomes are present. Sister

154. The resting stage in mitosis is called interphase. 163. The chromosomes which are exactly similar and
bear same genes at same loci are called______
Ans : MAIN 2023
chromosomes.
True.
Ans : MAIN 2007

155. Duplicated chromosomes remain attached at a Homologous

point termed centrosome.
164. The chromosome number is______in meiosis.
Ans : COMP 2020
Ans : COMP 2021
False. Duplicated chromosomes remain attached
at a point termed centromeres. Halved
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

165. The process by which cell multiplies is 173. The exchange of chromatid parts between the
called______. maternal and the paternal chromatids of a pair of
homologous chromosomes during meiosis.
Ans : SQP 2004

Cell division Ans : MAIN 2016

Crossing over
166. The chromosomes move to the opposite poles
in______stage. 174. The kind of division that takes place in the
reproductive tissues.
Ans : COMP 2017

Anaphase Ans : COMP 2010

Anaphase
167. Meiosis I is also known as______division.
175. The repeating components of each DNA strand
Ans : MAIN 2001
lengthwise.
Reductional
Ans : SQP 2016

Deoxyribonuleotide
DIRECTION : Choose the ODD one out from the
following terms given and name the CATEGORY to 176. An alteration in the genetic material that can be
which the others belong: inherited.
Example : Nose, Tongue, Arm, Eye Ans : COMP 2016
Answer : Odd Term - Arm, Category - Sense
organs Mutation

168. Centrosome, Cell wall, Cell membrane, Large

DIRECTION : Distinguish between the following on
vacuoles
the basis of what is given in the brackets:
Ans :
177. Karyokinesis and Cytokinesis. (explain the term)
Odd term - Centrosome, Category - Parts of plant
cell Ans : MAIN 2010

Karyokinesis is the division of the nucleus into

169. Phosphate, RNA, Sugar, Nitrogenous base
two daughter nuclei. There are mainly four steps
Ans : MAIN 2018 involved in karyokinesis and they are prophase,
RNA : Rest are components of DNA metaphase, anaphase and telophase.
Cytokinesis is the division of the cytoplasm to
form two daughter cells. It varies in plant and
DIRECTION : Give appropriate biological or
animal cells. Cytokinesis follows the karvokinesis.
technical terms for the following :
178. Mitosis and Meiosis. (number of daughter cells
170. The suppressed alleles of a gene. formed)
Ans : COMP 2017 Ans : COMP 2004
Recessive Mitosis – Two daughter cells are formed.
Meiosis – Four daughter cells are formed.
171. The complex consisting of a DNA strand and a
core of histones.
DIRECTION : Correct the following statements by
Ans : SQP 2018
changing the underlined words :
Nucleosome
179. Nitrogen bonds are present between the
172. Expand the following biological abbreviations
complementary nitrogenous bases of DNA.
DNA.
Ans : SQP 2018
Ans : SQP 2019
Hydrogen
Deoxyribonucleic acid
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 29

DIRECTION : Identify the odd one from a set of Ans : SQP 2004

four terms and name the category to which the other Prophase, metaphase, anaphase, telophase.
three belong.
DIRECTION : Match the following:
180. Thymine, Cytosine, Adenine, Pepsin.
Ans : COMP 2016 187. Column ‘B’ is a list of terms related to ideas in
Odd one: Pepsin column ‘A’. Match the term in column ‘B’ with
Category: Nitrogen base bases of DNA (thymine, the suitable idea given in column ‘A’.
cytosine, adenine). Column A Column B
181. Phosphate, RNA, Sugar, Nitrogenous base (i) Chromosomes (a) Anaphase
become arranged in
Ans : MAIN 2017
a horizontal plane at
Odd one: RNA the equator.
Category: Components of DNA
(ii) Daughter (b) Prophase
chromosomes move
DIRECTION : Rewrite the following terms into to opposite poles of
logical sequence: the spindle.

182. Karyokinesis, S-phase, cytokinesis, G-1 phase, (iii) Chromosomes (c) Telophase
G-2 phase. become visible as
fine, long threads.
Ans : MAIN 2012
(iv) Chromosomes lose (d) Metaphase
G-1 phase, S-phase, G-2 phase, karyokinesis,
their distinctiveness
cytokinesis.
and generally become
183. Interphase, Anaphase, Prophase, Telophase, transformed into
Metaphase chromatin network.

Ans : SQP 2018 Ans : SQP 2017

Interphase Prophase $ Metaphase $

Anaphase $ Telophase. Column A Column B
(i) Chromosomes (d) Metaphase
DIRECTION : Given below are groups of terms. In become arranged in
each group the first pair indicates the relationship a horizontal plane at
between the two terms. Rewrite and complete the the equator.
second pair on a similar basis. (ii) Daughter (a) Anaphase
Example: Oxygen : Inspiration : : Carbon dioxide: chromosomes move
Expiration to opposite poles of
the spindle.
184. Cytoplasm : Cytokinesis : : Nucleus :______
(iii) Chromosomes (b) Prophase
Ans : become visible as
Cytoplasm : Cytokinesis : : Nucleas : Karyokinesis. fine, long threads.

185. Adenine : Thymine : : Cytosine :______ (iv) Chromosomes lose (c) Telophase
their distinctiveness
Ans : COMP 2017
and gradually
Adenine : Thymine : : Cytosine : Guanine become transformed
into chromatin
186. Write the terms in correct order so as to be in network.
logical sequence:
Metaphase; telophase; prophase; anaphase.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

DIRECTION : State the differences between the 191. Cytokinesis in plant and animal cell
following pairs:
Ans : SQP 2002

188. Mitosis and Meiosis The differences between Cytokinesis in plant and
animal cell are as follows :
Ans : MAIN 2020

The differences between Mitosis ans Meiosis are Cytokinesis in plant Cytokinesis in
as follows : cell animal cell
(a) It starts with a cell Cell plate formation
Mitosis Meiosis plate formation. is absent. A
(a) It is an equational It is a reductional constriction furrow
division. division. forms in the middle
of cell membrane.
(b) Two diploid Four haploid
daughter cells are daughter cells are (b) It is centrifugal. It is centripetal.
formed. formed.
(c) Only one division Two divisions 192. Mitosis in animal and plant cell
occurs. occur. Ans : MAIN 2008

(d) It occurs in somatic It occurs in The differences between Mitosis in animal and
cells. reproductive cells. plant cell are as follows :

Mitosis in Animal Mitosis in Plant

189. Centrosome and Centromere Cell Cell
Ans : SQP 2023 (a) Centrosome is Centrosome is
present. absent.
The differences between Centrosome and
Centromere are as follows : (b) Asters and spindle Asters are not
formation occurs. formed.
Centrosome Centromere
(c) In telophase, In telophase, a cell
(a) It is an organelle of It is a point at cytoplasm constrict. plate is laid in the
the animal cell. which the duplicate cytoplasm at the
chromosomes are equatorial plane.
joined.
(b) It contains two It provides site 193. Asexual and Sexual Reproduction
centrioles which for attachment Ans : SQP 2001
move towards the of spindle fibres
opposite poles and during cell division. The differences between Asexual and Sexual
form spindle fibres Reproduction are as follows :
during cell division. Asexual Sexual
Reproduction Reproduction
190. Cytokinesis and Karyokinesis
(a) It is a type of Gametes are
Ans : COMP 2008 reproduction produced.
The differences between Cytokinesis and without gamete
Karyokinesis are as follows : formation.
(b) Variations are not Variations are
Cytokinesis Karyokinesis
produced. produced.
(a) It is the division of It is the division of
cytoplasm. nucleus. 194. S-phase and G2-phase
(b) It takes place after It is the first Ans : COMP 2009
Karkyokinesis. division. The differences between S-phase and G2-phase are
as follows :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 31
Ans : MAIN 2000
S-phase G2-phase
A gene is a unit of heredity composed of DNA.
(a) Replication of DNA rRNA and mRNA
occurs in this phase. are synthesised in 202. What are the two forms of genes known as ?
this phase.
Ans : COMP 2017

(b) At this stage, the At this stage, the The two forms of genes are called alleles.
cell contains 2n of cell contains 4n of
DNA. DNA. 203. Where does Meiosis occur in our body ?
Ans : SQP 2021

Meiosis occurs in the reproductive organs (testis

DIRECTION : Answer the following :
and ovary) of our body.
195. What are the two divisions that follow during cell 204. What happens during metaphase of mitosis?
division ?
Ans : SQP 2011
Ans : MAIN 2000
During metaphase of mitosis, chromosomes are
Karyokinesis and cytokinesis. arranged at the equator.
196. How many meiotic divisions are necessary to 205. What is synapsis?
produce 100 pollen grains ?
Ans : MAIN 2018
Ans : COMP 2022
Synapsis is the pairing of homologous chromosomes.
25 meiotic divisions. It occurs in zygotene stage of meiosis I.
197. What is synapsis ?
Ans :
Pairing of homologous chromosomes during TWO MARKS QUESTIONS
zygotene stage of meiosis is called synapsis.

198. Name two animals which have nineteen pairs of 206. During Mitosis what is the position of chromatids
chromosomes. in:
(a) Metaphase
Ans : COMP 2004
(b) Anaphase
Lion ; Tiger.
Ans : SQP 2025

199. Write the names of four nitrogenous bases in a (a) In the equatorial plane
DNA molecule. (b) Sister chromatids separate and move towards
Ans : MAIN 2013 the opposite poles.

The four nitrogenous bases in a DNA molecule 207. Draw a well labelled diagram to show the
are : anaphase stage of mitosis in a plant cell having
1. Adenine four chromosomes.
2. Guanine
Ans : COMP 2005
3. Cytosine
4. Thymine

200. Give the specific function of Centrosome

Ans : SQP 2009

Centrosome initiates and regulates cell division

in animal cells by forming spindle fibres with the
help of asters.

201. What is a gene ?

CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

208. How is variation produced in a species ? 2. DNA is synthesized.

3. Cell increases in size.
Ans : MAIN 2001

During meiosis, exchange of genetic material 214. What is a sat chromosome ?

between non-sister chromatids occur resulting in Ans : SQP 2002
new combinations. These combinations give rise
to variation resulting in the evolution of species. Sometimes the chromosomes bear round,
elongated or knob like appendages known as
209. Why is the first division of meiosis called as satellites. The satellite remains connected to the
reductional division ? rest of the chromosomes with satellites are called
sat chromosomes.
Ans : SQP 2017

The first division of meiosis is called as reductional 215. The figure shows two types of chromosomes.
division because in this division the chromosome Identify them and give reason for your choice.
number is reduced to half.

210. Why do gametes have a haploid number of

chromosomes ?
Ans : COMP 2019

Gametes have a haploid number of chromosomes

in order to maintain the 2n chromosome of
diploid zygote, when they fuse together to form
the zygote. Ans : COMP 2009

A – Metacentric : The centromere is present in

211. State how does meiosis maintain the chromosome the centre and two arms of the chromatids are
number in a species? equal.
Ans : COMP 2023 B – Telocentric : The centromere is present at one
end of the chromosome.
The gametes are formed by meiosis during
which the number of chromosomes are reduced 216. What is the significance of mitosis?
to half, i.e gametes contain haploid number of
chromosomes. The male and female gametes fuse Ans : SQP 2015

to form a zygote. In this way meiosis maintains It helps in the growth, repair and development
the chromosome number in a species. of the body. It is a type of reproduction in
protozoans.
212. Name the type of cell division that occurs during :
(i) Growth of shoot 217. State the importance of meiosis.
(ii) Formation of pollen grains Ans : MAIN 2003
(iii) Repair of worn out tissues
The importance of meiosis are as follows :
Ans : SQP 2017 (i) It brings about variations in a species.
(ii) It maintains the chromosome number of a
(i) Mitosis
species.
(ii) Meiosis
(iii) It helps in evolution of species.
(iii) Mitosis
218. Name the cell division that takes place during
213. What is Interphase ? Mention Three significant
gametogenesis. What is its significance ?
changes that occur in a cell during Interphase.
Ans : SQP 2020
Ans : MAIN 2010
Meiosis occurs during gametogenesis.
In between two divisions, when a cell is resting or
Its significance is that it helps to restore the
non-dividing, the phase is called interphase. The
number of chromosomes of the species.
three significant changes that occur in cell during
interphase are : 219. Why is variation seen in progeny ?
1. Chromatin material duplicates.
Ans : COMP 2013
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 33

The exchange of the chromosome material Ans : MAIN 2019

during crossing over provides innumerable In a plant cell, a cell plate is formed between
recombinations because of which the off-springs the two daughter nuclei. It grows outwards and
of the same parents however similar are different ultimately touches the cell wall. It forms the
from each other in some respects. The variations middle lamella.
are one of the important cause of evolution.
227. What are the various ways in which pairing occurs
220. What is crossing over? during zygotene?
Ans : SQP 2010 Ans : SQP 2014

It is the process of exchange of genetic material Pairing may start from both the ends and move
between the non-sister chromatids of homologous towards the centre, it may start from the centre
chromosomes. It occurs during pachytene stage and move towards either end of the nucleus.
of meiosis.
228. What happens during prophase of mitosis?
221. How does meiosis maintain chromosome number?
Ans : COMP 2010
Ans : SQP 2005
During prophase, chromatin material starts
During meiosis, chromosome number in the cell condensing to form chromosomes. Each
is reduced to half. The gametes contain haploid chromosome contains two chromatids joined at
number of chromosomes. During fertilisation, the the centromere. Nuclear membrane and nucleolus
male and the female gametes fuse and form a disappears. Spindle fibres appear between the two
diploid cell. centrioles.

222. Meiosis is referred to as reduction division. Why? 229. Identify and name the following processes/terms
Ans : COMP 2000 from the statements given below:
(i) Chromosomes appear thread like.
Meiosis is called reduction division because
(ii) A pair of chromosomes carrying dissimilar
chromosome number reduces to half in daughter
alleles for a particular character.
cells.
Ans : COMP 2018
223. Why is meiosis essential in sexually reproducing
(i) Chromatin fibres.
organisms?
(ii) Heterozygous chromosomes.
Ans : MAIN 2008
230. Give reason: Gametes have a haploid number of
Meiosis helps to maintains a definite number of
chromosomes.
chromosomes in a species; crossing over which
occurs during meiosis produces variations. Ans : SQP 2020

Gametes are formed after meiosis. During meiosis,

224. What is a SAT chromosome?
reduction of the number of chromosomes occurs.
Ans : COMP 2012 So, during fertilisation the original number of
Sometimes a few chromosomes have a secondary chromosomes are retained.
constriction. The part of the chromosome beyond
231. State the functions of chiasmata.
the secondary constriction is called satellite. Such
chromosomes are called SAT chromosomes. Ans :. MAIN 2004

225. How does cytokinesis occur in an animal cell? The functions of chiasmata are as follows :
(i) Crossing over takes place at the chiasmata
Ans : SQP 2022 during meoisis.
In an animal cell, a cleavage/furrow appears (ii) To hold the homologous chromosomes
during telophase in the plasma membrane. This together prior to segregation.
furrow deepens and meets in the middle to form
232. What are the changes that occur during S-phase?
two daughter cells.
Ans : SQP 2012
226. How does cytokinesis occur in a plant cell?
S-phase: During this phase, replication of DNA
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

takes place. Each chromosome contains two Figure A, is acrocentric; Figure B, is metacentric.
sister chromatids and are attached to a common In acrocentric chromosome, the centromere is
centromere. near to terminal region while in metacentric, the
centromere is in the centre of the chromosome.
233. Briefly explain the types of chromosomes
according to the positions of centromere.
Ans : COMP 2017

Based on the position of centromere, the THREE MARKS QUESTIONS

chromosomes are of four types:
1. Telocentric – It has a terminal centromere.
237. The given figure shows a cell. Study the figure
2. Acrocentric – Centromere is near to one end.
and then answer the questions that follow :
3. Submetacentric – Centromere is slightly away
(i) Identify the stage of cell cycle depicted by the
from the centre.
cell.
4. Metacentric – Centromere is in the middle.
(ii) Write any two characteristics of this phase.
234. What is DNA fingerprinting ? (iii) What are the main events which take place
when the cell goes into the next stage ?
Ans : SQP 2013

There are regions in between genes which are non-

functional. These areas/regions show tremendous
variation from individual to individual and are
peculiar from person to person. This technique is
commonly known as DNA fingerprinting.
or
It is a technique used to identify and analyse the
variations in various individuals at the level of
DNA. It is based on variability and polymorphism
in DNA sequences.
Now a days this technique is used to a great
extent in forensic science. Ans : MAIN 2009

235. The term ‘stem cells’ are often heard these days. (i) Inter-phase
Explain briefly of what it means. (ii) Inter-phase of a cell is characterized by :
1. Growth in cell size.
Ans : COMP 2017
2. Duplication of chromatin material and
Stem cells are biological cells that has the ability gets thinned and coiled up.
to differentiate into specialized cell types (mainly (iii) As the cell enters the next stage (Prophase)
into different tissues and organs). the following events take place :
They are generally found in multicellular 1. Centrioles become free and begin to move
organisms. towards the opposite poles.
2. Astral rays are developed and
236. The figure A and B show two types of chromosomes, chromosomes are seen.
identify them and write the difference. 3. Nuclear membrane and nucleolus starts
disappearing.

238. Try to guess the time period (in terms of days or

years) of how long the following cells last or are
replaced in human body.
(a) Liver cells
(b) Bone cells
(c) Epithelial cells of the gut
(d) Skin cells
Ans : COMP 2006 (e) RBC
(f) Eye, nerve and muscle cells
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 35
Ans : SQP 2007

(a) 300-500 days

(b) Every 10 years (approximately
(c) 5 days
(d) Every 14-15 days
(e) 120 days (approximately)
(f) Life time

239. The given figure represents a certain phenomenon

that occurs during meiosis:

241. Identify the stages of meiosis and label the parts

1 to 5.

(i) Name of the phenomenon. Ans : MAIN 2008

(ii) Define the phenomenon.
(iii) State the difference between chromosomes Anaphase-II
and chromatids. 1. Centriole;
2. Aster ray;
Ans : MAIN 2008 3. Spindle fibre;
(i) Crossing over. 4. Chromatid,
(ii) It is the exchange of genetic material between 5. Centromere
the non-sister chromatids of homologous
242. Draw the diagram of the following :
chromosomes.
(i) A cell cycle
(iii) Chromosomes are the carriers of heredity.
(ii) Telophase stage of mitosis in plant cell.
Chromatids are the two identical strands of a
duplicated chromosome. Ans : SQP 2017

240. With the help of neat sketches show how (i)

cytokinesis differs in a plant cell and in an animal
cell.
Ans : COMP 2013

(ii)
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

shown in the diagram. Draw a neat labelled

diagram of the stage mentioned.
(v) Which is the cell division that results in half
the number of chromosomes in daughter cells?
Ans : COMP 2017

(i) Telophase.
The reasons are:
1. Two sets of daughter chromosomes are
seen on the opposite poles of the cell.
2. Reappearing of nuclear membrane and
nucleoli.
243. Draw a diagram of the nucleus of a cell, having 3. Formation of the chromatin fibres and
chromosome number 6, as it would appear in the deepening of cleavage furrow.
metaphase stage of mitosis and label the following (ii) 1. chromosomes
parts: 2. Nuclear membrane.
(a) Aster rays, (b) Acromatic spindle, (c) (iii) Karyokinesis.
Chromatid, (d) Centromere. (iv) Anaphase.
Ans : MAIN 2020

(v) Meiosis.

245. The diagram below represents a stage during cell

division. Study the same and then answer the
questions that follow :

FIVE MARKS QUESTIONS

244. Study the diagram given below which represents

a stage during the miotic cell division and answer
the questions that follow:

(i) Name the parts labelled 1, 2 and 3

(ii) Identify the above stage and give a reason to
support your answer.
(iii) Mention where in the body this type of cell
(i) Identify the stage giving suitable reasons.
division OMITS.
(ii) Name the parts numbered 1 and 2.
(iv) Name the stage prior to this stage and draw
(iii) What is the technical term for the division of
a diagram to represents the same.
nucleus?
(iv) Mention the stage that comes before the stage Ans : SQP 2011
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 37

(i) 1. Aster with astral rays (Centriole) 247. The diagram given below represents a certain
2. Spindle fibre and stage of mitosis:
3. Daughter chromosome.
(ii) Late Anaphase, as splitting of chromosome
takes place and daughter chromosome
proceeds towards the poles.
(iii) Somatic cells
(iv) Metaphase

(i) Identify the stage of cell division.

(ii) Name the parts labelled A and B.
(iii) What is the unique feature observed in this
stage?
(iv) How many daughter cells are formed from
this type of cell division?
246. There is a diagram of a double helical structure Ans : COMP 2015
of DNA: (i) The phase is Anaphase.
(i) Name the four nitrogenous bases that form a (ii) A – Spindle fibre
DNA molecule. B – Centromere/kinetochore
(ii) Give the full form of DNA. (iii) The unique feature is that the spindle fibres
(iii) Name the unit of heredity. are contracting and sister chromatids/
(iv) Mention two points of difference between daughter chromosomes are moving towards
Mitosis and Meiosis. the opposite poles of the cell.
(iv) Two daughter cells are formed from this type
of cell division.

248. The given diagram shows a stage during mitotic

division in an animal cell :
(i) Identify the stage. Give a reason to support
your answer.

Ans : COMP 2010

(i) Adenine, guanine, thymine and cytosine.

(ii) Deoxyribonucleic acid.
(iii) Genes.
(iv)

Mitosis Meiosis
(a) It occurs in the (a) It occurs in the (ii) Draw a neat labelled diagram of the cell as
somatic cells. reproductive it would appear in the next stage. Name the
cells. stage.
(b) Two daughter (b) Four daughter (iii) In what two ways is mitotic division in an
cells are formed. cells are formed animal cell different from the mitotic division
in a plant cell ?
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

(iv) Name the type of cell division that occurs Spindle fibres.
during: (iii) The division of centromere helps in the
A. Growth of a shoot separation of two sister chromatids of each
B. Formation of pollen grains. chromosome, which are drawn apart towards
opposite poles.
Ans : SQP 2016
(iv) Metaphase
(i) Prophase-Nuclear membrane and nucleolus
disappear, chromatin resolve into
chromosomes.
(ii) Next stage is as shown below :

(iii) In animal cell, amphiastral spindle is formed 250. Given below is diagram representing a stage
whereas it is anastral spindle in the plant cells. during mitotic cell division. Study it carefully and
Secondly, in animal cells, cytokinesis takes answer the questions that follow:
place centripetally by constriction whereas in
plant cells, it is centrifugally by the formation
of cell plate.
(iv) A-Mitosis and B-Meiosis.

249. Given diagram representing a stage during mitotic

cell division in an animal cell :

(i) Is it a plant cell or an animal cell? Give a

reason to support your answer.
(ii) Identify the stage shown.
(iii) Name the stage that follows the one shown
here. How is that stage identified?
(iv) How will you differentiate between mitosis
(i) Identify the above stage. Give a reason to and meiosis on the basis of the chromosome
support your answer. number in the daughter cells?
(ii) Name the parts labelled 1, 2, 3 and 4. (v) Draw a duplicated chromosome and label its
(iii) What is the function of part 3? parts.
(iv) Name the stage that comes just after the
stage shown in the diagram. Draw a well Ans : COMP 2014

labelled diagram of this stage. (i) Plant cell:

Ans : MAIN 2010
1. It has cell wall.
2. Centrioles not present.
(i) Late prophase. Reason : Centrosome splits (ii) Prophase.
into two, occupying each pole, nuclear (iii) Metaphase. Chromosomes arrange themselves
membrane degenerating and chromosomes upon the equator of a spindle.
move towards the equator of the cell, spindle (iv) Mitosis – 46 chromosomes
fibres appear between two asters (centrioles). Meiosis – 23 chromosomes
(ii) 1. Astral rays 2. Chromatid 3. Centromere 4. (v)
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 39

252. The given diagram shows a stage during mitotic

division in an animal cell:
(i) Identify the stage. Give a reason to support
your answer.
(ii) Draw a neat labelled diagram of the cell as it
would appear in the next stage. Name the stage.
(iii) In what two ways is mitotic division in an
animal cell different from the mitotic division
in a plant cell?
(iv) Name the type of cell division that occurs
251. Given below is a diagram representing a stage during:
during the mitotic cell division. Study the diagram
and answer the following questions :

(i) Identify the stage by giving a suitable reason.

(ii) Is it a plant or an animal cell ? Give a reason
to support your answer. A. Growth of a shoot
(iii) Draw a neat, labelled diagram of the stage B. Formation of pollen grains.
which follows the one shown in the diagram.
Ans : COMP 2016
(iv) How many chromosomes will each daughter
cell have after the completion of the above (i) Prophase Reason – Nuclear membrane is
division ? disappearing.
(v) Name the four nitrogenous bases. (ii)
Ans : SQP 2019

(i) Anaphase : Two sister chromatids move

towards opposite poles.
(ii) Animal cell : No cell wall; presence of
centrioles at opposite poles.
(iii)

(iii)

Mitosis in plants Mitosis in

animals
(a) Asters are not (a) Asters are
formed due to formed.
lack of centrioles.
(b) Formation of (b) A constriction
cell plate in forms in the
(iv) Four telophase. cytoplasm in
(v) Adenine, Guanine, Cytosine, Thymine telophase.
(iv) A. Mitosis, B. Meiosis.
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

253. Given is a diagram representing a stage during (iii) Name the type of cell division that occurs
mitotic cell division in an animal cell. during:
(i) Identify the stage. Give a reason to support 1. Replacement of old leaves by new ones.
your answer. 2. Formation of gametes.
(ii) Name the cell organelle that forms the aster. (iv) What is the stage that comes before the stage
(iii) Name the parts labelled 1, 2 and 3. shown in the diagram ?
(iv) Name the stage that follows this stage of (v) Draw a neat, labelled diagram of the stage
mitosis. How can this stage be identified? mentioned in above keeping the chromosome
number constant.
Ans : SQP 2012

(i) Animal cell : Centriole is present. [It can be a

plant cell also as it is double layered (cell wall
present) and astral rays are absent].
(ii) Metaphase : Unique feature is chromosomes
are arranged at the equatorial plate
(metaphasic) plate.
(iii) 1. Mitosis
2. Meiosis
(iv) Prophase
(v)

Ans : MAIN 2010

(i) Late prophase. The reason is that nuclear

membrane disappears.
(ii) Centrosome (centrioles).
(iii) 1. Centromere, 2. Chromosome, 3. Spindle
fibres
(iv) Metaphase. The chromosomes arrange
themselves on the equatorial or metaphase
plane.

254. The diagram given below represents a stage

during cell division.
Study the same and answer the questions that
follow : 255. Study the diagram given below which represents a
stage during the mitotic cell division and answer
the questions that follow :

(i) Identify the stage giving suitable reasons.

(i) Identify whether it is a plant cell or an animal (ii) Name the parts numbered 1 and 2.
cell. Give a reason in support of your answer. (iii) What is the technical term for the division of
(ii) Name the stage depicted in the diagram. nucleus?
What is the unique feature observed in this (iv) Mention the stage that comes before the stage
stage? shown in the diagram. Draw a neat labelled
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 41

diagram of the stage mentioned.

(v) Which is the cell division that results in half
the number of chromosomes in daughter cells?
Ans : SQP 2017

(i) The stage is Telophase. The reason is the

nucleus and nucleolus reappears and spindle
fibres disappeard.
(ii) 1. Centromere
2. Nuclear membrane/Nucleus
(iii) Karyokinesis
(iv) Anaphase (iii) Metaphase
(iv) Centromere/kinetochore
(v) Mitosis : Mitosis is a type of cell division in
which each chromosome of a parent cell splits
up longitudinally into two identical halves,
each half going to each of the daughter cell.

257. The figure shows a certain stage in cell division in

a cell with 4 chromosomes.

(v) Meiosis

256. The diagram represents the four stages of cell

division. Study the diagram carefully and then
answer the following questions :

(i) Name the parts labelled A and B.

(ii) What is C ? Give its function.
(iii) Name the type of division with a logic reason.
(iv) Name the stage before and the stage after the
stage shown in the diagram.
(i) What are the four stages of cell division ?
Ans : MAIN 2013
(ii) Label the various parts indicated after
rearranging the four stages in sequential (i) A is chromatid
order. B is centromere
(iii) In which stage the chromosomes undergo (ii) C is spindle to which chromosomes attach.
maximum condensation and arrange The spindle fibres pull the chromatids apart.
themselves in the equatorial plate ? (iii) Mitosis.
(iv) Name the structure by which the chromosomes The chromosomes line up on the spindle
get attached to the spindle fibres. singly. If it were meiosis the chromosomes
(v) Define the type of cell division that is would be in homologous pair.
represented in the above diagram. (iv) The stage before is interphase and the stage
after is metaphase.
Ans : COMP 2009

(i) 1. Prophase 258. Give one point of difference on the basis of what
2. Metaphase is given in the brackets:
3. Anaphase (i) Metacentric and Telocentric chromosomes
4. Telophase. –(Position of centromere)
(ii) (ii) Mitosis and Meiosis
–(Number of daughter cells formed)
CH 1 : CELL CYCLE AND STRUCTURE OF CHROMOSOMES

(iii) Maternal and Paternal chromosomes (ii) Name the parts labelled A, B, C and D.
–(Source) (iii) Where does this type of cell division usually
(iv) Chiasmata and Crossing over –(Function) occur?
(v) Mitosis in animal cell and Mitosis in plant cell (iv) Is the dividing cell shown as a plant or an
–(Telophase stage) animal cell? Give a reason to support your
answer.
Ans : MAIN 2002
Ans : SQP 2017
(i) Metacentric Telocentric (i) Anaphase.
chromosomes chromosomes (ii) A. Spindle fibre; B. Cell wall; C. Chromatid;
Centromere Centromere is D. Centromere.
is present in present at one end (iii) In the body (somatic) cells.
the centre of of chromosome. (iv) It is a plant cell as presence of cell wall, is
chromosome. shown clearly.
(ii) Mitosis Meiosis
Two daughter cells Four daughter cells
from one single from a single cell.
cell. CASE BASED QUESTION
(iii) Maternal Paternal
chromosomes. chromosomes
260. In living organisms, cell division is essential for
These These chromosomes
growth, development, repair, and reproduction.
chromosomes are are from father’s
Somatic (body) cells contain an even number of
from mother’s side. side.
chromosomes (2n). Mitosis ensures the creation of
(iv) Chiasmata Crossing over identical cells for growth and repair, while meiosis
It is the point of It is the exchange produces gametes with half the chromosome
attachment of non- of genetic material number, ensuring genetic diversity in sexually
sister chromatids between non- reproducing organisms.
of homologous sister chromatids 1. How does mitosis contribute to tissue repair?
chromosomes of homologous 2. Why is meiosis important for reproduction?
where crossing chromosomes. 3. What is the significance of an even number of
over takes place. chromosomes (2n) in somatic cells?
(v) Mitosis in animal Mitosis in plant cell 4. Briefly differentiate between mitosis and
cell In telophase stage, meiosis.
In telophase a cell plate is laid in Ans :
stage, cytoplasm the cytoplasm at the
1. Mitosis helps in tissue repair by producing
constricts. equatorial region.
identical cells to replace damaged ones.
2. Meiosis is crucial for reproduction as it halves
259. The diagram represents a stage in cell division. the chromosome number in gametes.
Study the same and answer the questions that 3. An even chromosome number ensures proper
follow: division and genetic stability in somatic cells.
4. Mitosis creates identical cells for growth,
while meiosis forms gametes for reproduction.

261. Interphase is a preparatory phase where the

cell grows, duplicates its DNA, and gets ready
for division. It is divided into three sub-stages:
G1 phase (cytoplasm increases, and proteins are
synthesized), S phase (DNA synthesis), and G2
phase (spindle proteins for mitosis are formed).
After completing interphase, the cell must divide
through mitosis.
(i) Identify the stage of cell division.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 43

1 What happens to the chromatin material contain around 130,000 genes. While all body
during interphase? cells contain the same number of chromosomes
2. Describe the role of the G1 phase in interphase. and genes, some genes are active in all cells, like
Why is DNA synthesis important during the those involved in respiration. Others, like the gene
S phase of interphase? for insulin production, are only active in specific
3. What is the significance of the G2 phase in cells such as the beta cells of the pancreas.
preparing for mitosis? 1. What is the role of genes in heredity and
where are they located?
Ans :
2. Why are some genes active in all cells, while
1. The chromatin material duplicates during others are only active in specialized cells?
interphase due to DNA synthesis. 3. How many genes have scientists identified
2. In the G1 phase, the cytoplasm increases, and in human chromosomes, and what does this
protein synthesis occurs. suggest about genetic complexity?
3. DNA synthesis in the S phase is crucial for 4. Explain the function of the insulin-producing
duplicating genetic material before division. gene and where it is specifically active.
4. The G2 phase prepares the cell for mitosis by
synthesizing necessary spindle proteins. Ans :
1. Genes determine hereditary traits and are
262. Mitosis is the process where a single cell divides located in fixed positions on chromosomes.
to form two identical daughter cells. It consists of 2. Some genes are active in all cells for essential
two parts: karyokinesis (division of the nucleus) functions like respiration, while others, like
and cytokinesis (division of the cytoplasm). insulin genes, are active only in specialized
Karyokinesis includes four stages: prophase, cells.
metaphase, anaphase, and telophase. Afterward, 3. Scientists have identified about 130,000
cytokinesis splits the cytoplasm, completing the genes in human chromosomes, indicating the
cell division. complexity of genetic information.
1. What significant changes occur during 4. The insulin-producing gene is functionally
prophase in both animal and plant cells? active only in the beta cells of the pancreas.
2. What happens to the chromosomes during
metaphase and how is it significant? www.nodia.in
3. Explain how the chromatids behave in
anaphase and the result of this movement.
4. Describe the process of cytokinesis in animal
and plant cells.
Ans :
1. In prophase, chromosomes condense, spindle
fibers form, and the nuclear membrane
disappears in both plant and animal cells.
2. During metaphase, chromosomes align at the
equatorial plate, ensuring equal chromosome
distribution to daughter cells.
3. In anaphase, sister chromatids separate and
move to opposite poles, forming two groups
of chromosomes.
4. In animal cells, cytokinesis occurs through a
furrow, while in plant cells, a cell plate forms
to divide the cytoplasm.

263. Genes, which are specific parts of chromosomes

composed of DNA, determine hereditary traits and
are responsible for passing characteristics from one
generation to another. Each gene occupies a fixed
position in a chromosome. Human chromosomes
CH 2 : GENETICS

CHAPTER 2
GENETICS

Mendel in his work :

SUMMARY

1. GENETICS
Genetics is described as the study of transmission
of body features from parents to off -springs
and the laws relating to such transmission. It is
the science which deals with the mechanism of
heredity and variations.

2. HEREDITY
Heredity is the study of transmission of genetically
based characters from parents to off-springs.

3. VARIATIONS
These are small differences among individuals.
All human beings are similar but they show so
many types of races due to the variations in
their characters. These are observed in animals
and plants. The greatest advantage of variation
in a species is that they increase the chances of
survival in a changing environment.

4. GENETIC ENGINEERING
It is the technique in which the genetic constitution
of an organism is altered by introducing new genes
into its chromosomes.
Gregor Johann Mendel is known as “Father of
Genetics”. He conducted breeding experiments
on garden pea (Pisum sativum). The reasons for
selecting garden pea for his experiments were
that:
1. Many varieties were available having
contrasting characters.
2. Varieties were available in pure forms.
Deoxyribonucleic Acid (DNA) is a substance
3. Peas are self pollinated since it is bisexual.
within the chromosomes that carries the hereditary
4. Self pollination could be prevented by
instructions for producing proteins while RNA is
removing corresponding reproductive parts of
a substance similar to DNA that transmits DNA’s
the flower.
instructions for making proteins from the nucleus
5. Cross pollination could be done artificially.
to the cytoplasm of the cells. Diploid cells contain
6. Reproductive span of pea plant is very small.
two sets of chromosomes, one from each parent.
The seven pairs of contrasting characters used by
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 45

5. HOMOLOGOUS CHROMOSOMES
These are a pair of corresponding chromosomes
of the same shape and size, one from each parent.
All genes are specific parts of chromosomes which
determine hereditary characters.

6. ALLELES OR ALLELOMORPHS
These are alternative forms of gene occupying
same position on homologous chromosomes and
affecting the same characteristic but in different
ways.
Two genes are present in a homologous pair for
any one particular trait.
Normally one gene in every pair is dominant. It 9. DIHYBRID CROSSES
hides the effects of its recessive partner. These are Mendelian crosses in which two pairs of
Recessive genes show their effect only if there are contrasting characters are taken into consideration
two of them. It is not expressed in the presence of at a time.
a dominant allele. Mendel’s Laws of Inheritance :
1. Law of Dominance : In heterozygous condition
6.1 Homozygous
out of two contrasting alleles one expresses
It means individuals having similar gene pairs, itself morphologically and the other remains
e.g., RR, rr. unexpressed. The allele which expresses
itself phenotypically in the presence of its
6.2 Heterozygous
contrasting allele is called dominant and the
It means individuals having dissimilar gene pairs, other which remains unexpressed is called
e.g., Rr. recessive.
2. Law of Segregation : The two factors
6.3 Genotype
controlling one character segregate without
Genotype is the genetic constitution of an organism influencing each other during the formation
with regards to one or more characters, e.g., An of gametes so that each gamete receives one
organism may have the genetic composition RR factor for each character.
or Rr or rr. 3. Law of Independent assortment : The
factors controlling different characters assort
7. PHENOTYPE independently without influencing each other
Phenotype refers to the observable characters of during the formation of gametes.
an organism which is genetically controlled. e.g.,
RR and Rr both are red (externally they look
same). This mean that they are phenotypically
same but they carry different genes and are
therefore said to be differ in genotype.

8. MONOHYBRID CROSSES
These are Mendelian crosses in which only
one pair of contrasting character is taken into
consideration at a time.
CH 2 : GENETICS

10. SEX LINKED INHERITANCE such genes are called holandric genes. Another
Colourblindness, haemophilia and night blindness example is baldness in males.
are some of the common X linked sex characters 12. MUTATION
which are controlled by the recessive genes present
on X chromosomes. These diseases are common It is a sudden change in one or more genes. It
in males than in females because both the X alters the hereditary material of an organism’s
chromosomes may not carry the abnormal gene in cells thereby causing changes in certain traits
the females. The gene which may be abnormal on (characters). A mutation can effect an individual
one X chromosome being recessive, its influence gene or an entire chromosome. The gene mutation
will be hidden by the normal gene on the other X is caused even by slight chemical changes in
chromosome. The male with one X chromosome DNA. e.g. sickle cell anemia (a blood disease). A
has only one gene for these diseases. If that is chromosomal mutation occurs if the number or
the abnormal gene then there is nothing on Y arrangements of genes on chromosome changes, for
chromosome to mask it and hence these diseases example, Downs syndrome also called mongolism
can occur easily. is a disorder which occurs if a person is born with
one extra chromosome. (47 chromosome).
11. HYPERTRICHOSIS (LONG HAIR ON THE PINNA) Colourblindness is checked by Ishihara cards.
It is present on the Y chromosome only. Since Crosses between two different animals :
Y chromosomes are found in males only that is 1. Horse + Zebra = HEBRA
why such traits are restricted in males only and 2. Tiger + Lioness = TIGON
3. Lion + Tigress = LIGER
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 47

4. Bison + Buffalo = BIFFALO Ans : MAIN 2021

5. Zebra + Horse = ZORSE Crossing a homozygous purple-flowered pea plant

6. Zebra + Donkey = ZENKEY (PP) with a homozygous white-flowered plant
(pp) produces all heterozygous purple-flowered
(Pp) plants in the F1 generation. When these
F1 plants are self-crossed (Pp × Pp), the F2
MULTIPLE CHOICE QUESTION generation shows a 3:1 phenotypic ratio of purple
to white flowers.
Thus (d) is correct option.
1. A male gorilla has 48 chromosomes in each of its
body cells. How many chromosomes will each of 4. The genotype of a person who cannot roll his
the sperms have? tongue is_______.
(a) Rr (b) RR
(c) rr (d) RRr
Ans : MAIN 2021

Tongue rolling is a dominant trait, so a person

who cannot roll their tongue has the recessive
genotype rr, meaning they inherited the non-
rolling allele from both parents.
Thus (c) is correct option.

5. Who is known as the "Father of Genetics"?

(a) 24 (b) 48 (a) Charles Darwin
(c) 12 (d) 16 (b) Gregor Johann Mendel
(c) Alfred Wallace
Ans : MAIN 2024
(d) Jean-Baptiste Lamarck
Since a male gorilla's body cells have 48
chromosomes, each sperm cell will contain 24 Ans : SQP 2017

chromosomes. This reduction occurs during Gregor Johann Mendel is regarded as the "Father
meiosis I, where the chromosome number is of Genetics" due to his pioneering work on
halved to produce haploid cells. inheritance patterns in garden peas, which laid
Thus (a) is correct option. the foundation for the laws of heredity.
Thus (b) is correct option.
2. The type of gene, which in the presence of a
contrasting allele is not expressed : 6. The basic units of heredity are______
(a) Homozygous (b) Heterozygous (a) Chromosomes (b) Chromatids
(c) Dominant (d) Recessive (c) Genes (d) Centrosome
Ans : COMP 2021 Ans : SQP 2021

The allele that fails to express itself in presence A gene is a basic unit of heredity. Each gene has a
of its contrasting dominant allele is called a specific code, and these codes are used to develop
recessive allele. They can only express themselves the characteristics of a person.
in homozygous conditions. For example, Tt is the Thus (c) is correct option.
genotype for tallness in which “t” is the recessive
7. Explain the following terms :
allele.
(i) Law of Dominance :
Thus (d) is correct option.
(a) Out of a pair of contrasting alleles present
3. A homozygous pea plant having purple flowers together, only the recessive allele is able
is crossed with a homozygous pea plant bearing to express itself while the dominant
white flowers. The phenotypic ratio of the remains suppressed.
offspring obtained in F2 generation is : (b) Out of a pair of contrasting alleles
(a) 2 : 1 (b) 1 : 1 present together, only the dominant allele
(c) 1: 2 : 1 (d) 3 : 1 is able to express itself while the recessive
remains suppressed.
CH 2 : GENETICS

(c) Out of a pair of contrasting alleles of 1:2:1 (homozygous dominant to heterozygous

present together, both the dominant and to homozygous recessive).
recessive cannot express themselves. Thus (a) is correct option.
(d) Out of a pair of contrasting alleles
present together, both the dominant and 10. Genetics is the study of:
recessive can express themselves. (a) Cells
(b) Transmission of characters
Ans : COMP 2021
(c) Tissue
This law was proposed by Gregor Mendel, stating (d) Origin
that in a heterozygous condition, the dominant Ans : MAIN 2000
allele will mask the effect of the recessive allele,
allowing only the dominant trait to be expressed. The transmission of characters from one
Thus (b) is correct option. generation to the next is called heredity. This
can be achieved in both asexually and sexually
(ii) Mutation :
reproducing organisms. DNA, also known as the
(a) It is a sudden change in one or more genes
genetic material is responsible for the transfer of
in an organism’s cells which is heritable.
traits from parents to their offspring.
(b) It is a change in the number of centrosomes
Thus (b) is correct option.
in an organism's cells which is heritable.
(c) It is a change in the structure of cell 11. What is the technique called where the genetic
membrane in an organism’s cells which is constitution of an organism is altered by
heritable. introducing new genes into its chromosomes?
(d) It is a change in the shape of cells which (a) Genetic mutation
is heritable. (b) Genetic engineering
Ans : MAIN 2017 (c) Cloning
(d) Gene therapy
Mutations refer to changes in the genetic material
(DNA or RNA), which can lead to variations in Ans : COMP 2011

traits. These changes can be passed on to the next Genetic engineering refers to the deliberate
generation if they occur in reproductive cells. modification of the characteristics of an organism
Thus (a) is correct option. by manipulating its genetic material, often by
introducing new genes into its chromosomes.
8. The recessive gene is one that expresses itself in:
Thus (b) is correct option.
(a) Heterozygous condition
(b) Homozygous condition 12. Why did Mendel choose garden pea (Pisum
(c) F2 generation sativum) for his experiments?
(d) Y-Linked inheritances. (a) They were easy to grow
Ans : COMP 2011 (b) They had many varieties with contrasting
The recessive gene is one that expresses itself in characters
homozygous condition. (c) They had a long reproductive span
Thus (b) is correct option. (d) They were available in pure forms

9. Rahul is studying a genetic cross between Ans : MAIN 2020

pea plants. His teacher asks him to recall the Mendel selected pea plants for his experiments
phenotypic ratio from Mendel's monohybrid cross. because they had distinct varieties with easily
Monohybrid phenotypic ratio is: observable contrasting traits (e.g., tall vs. short
(a) 3 : 1 plants, round vs. wrinkled seeds), making it ideal
(b) 2 : 3 for studying inheritance patterns.
(c) 9 : 3 : 3 : 1 Thus (b) is correct option.
(d) 1 : 2 : 1
13. Riya is conducting a genetics experiment with pea
Ans : SQP 2004
plants and wants to prevent self-pollination to
A monohybrid cross results in a phenotypic ratio of allow cross-pollination What method did Mendel
3:1 (dominant to recessive), and a genotypic ratio use to prevent self-pollination in pea plants?
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 49

(a) Removing corresponding reproductive parts chromosome to mask the effect.

(b) Natural pollination Thus (b) is the correct option.
(c) Artificial cross-pollination
(d) Chemical treatment 17. Which chromosome carries the gene for
colorblindness?
Ans : SQP 2011
(a) Y chromosome
Mendel prevented self-pollination by removing (b) Z chromosome
the reproductive parts (anthers) of the flower to (c) X chromosome
ensure that cross-pollination could be performed (d) W chromosome
artificially, allowing him to control the breeding
process. Ans : COMP 2016

Thus (a) is correct option. The gene for colorblindness is located on the X
chromosome, which is why it is referred to as an
14. Which of the following is not a reason Mendel X-linked disorder.
selected garden peas for his experiments? Thus (c) is the correct option.
(a) Peas have a small reproductive span
(b) Peas are self-pollinated 18. In females, why are X-linked diseases less
(c) Peas are uni-sexual common?
(d) Cross-pollination could be done artificially (a) Both X chromosomes may not carry the
Ans : MAIN 2018
abnormal gene, so one normal X can mask
the recessive gene
Garden peas are bisexual (having both male and (b) Females have stronger genes
female reproductive organs). Mendel's experiments (c) Females have a Y chromosome to compensate
involved the use of bisexual flowers, where self- (d) Females lack the ability to carry genetic
pollination occurs naturally, but he could prevent mutations
it by manually removing reproductive parts to
conduct artificial cross-pollination. Ans : MAIN 2010

Thus (c) is correct option. Females have two X chromosomes. If one X

chromosome carries the abnormal gene, the
15. Which of the following is a common X-linked normal gene on the other X chromosome can
recessive disease? mask the recessive gene’s effects.
(a) Diabetes Thus (a) is the correct option.
(b) Haemophilia
(c) Influenza 19. What happens when a male has an abnormal gene
(d) Asthma on his X chromosome?
(a) The Y chromosome masks it
Ans : SQP 2011
(b) The disease occurs because there is no gene
Haemophilia is an X-linked recessive disorder, on the Y chromosome to mask it
along with colorblindness and night blindness, (c) The abnormal gene is repaired by the body
meaning the gene responsible for the disease is (d) The gene causes no effect in males
located on the X chromosome.
Thus (b) is the correct option. Ans : COMP 2015

Males have only one X chromosome, and if

16. Why are X-linked recessive diseases more common it carries an abnormal gene, the disease will
in males? manifest because the Y chromosome does not
(a) Males have two X chromosomes have a corresponding gene to mask it.
(b) Males have one X chromosome and the Y Thus (b) is the correct option.
chromosome cannot mask the abnormal gene
(c) Females do not have X chromosomes 20. What is the primary focus of genetics?
(d) Males are more exposed to genetic mutations (a) The study of plant life
(b) The study of animal behavior
Ans : MAIN 2016
(c) The study of transmission of body features
Since males have one X and one Y chromosome, if from parents to offspring
the X chromosome carries the abnormal gene, the (d) The study of environmental changes
disease will express itself, as there is no second X
CH 2 : GENETICS
Ans : SQP 2018
25. Which plant did Mendel use for his experiments
Genetics is defined as the science that examines on genetics?
the transmission of body features from parents to (a) Corn
offspring and the laws governing this transmission. (b) Wheat
Thus (c) is the correct option. (c) Garden pea (Pisum sativum)
(d) Sunflower
21. What is heredity?
(a) The study of organisms' surroundings Ans :
(b) The transmission of genetically based traits Mendel used the garden pea plant for his
from parents to offspring experiments because of its contrasting
(c) The creation of new species characteristics and ease of manipulation.
(d) The study of plant anatomy Thus (c) is the correct option.
Ans : MAIN 2020
26. How many pairs of contrasting characters did
Heredity specifically refers to the passing of Mendel use in his work on pea plants?
genetic traits from parents to their offspring. (a) Five (b) Six
Thus (b) is the correct option. (c) Seven (d) Eight

22. What is the significance of variation in a species? Ans :

(a) It decreases chances of survival Mendel used seven pairs of contrasting characters
(b) It helps in creating identical organisms to study inheritance patterns in pea plants.
(c) It increases the chances of survival in a Thus (c) is the correct option.
changing environment
(d) It has no role in survival 27. Why did Mendel choose the pea plant for his
experiments?
Ans : (a) It is a bisexual plant
Variation provides genetic diversity, which can (b) It can self-pollinate
be advantageous for adapting to environmental (c) It has many varieties with contrasting
changes. characters
Thus (c) is the correct option. (d) All of the above

23. What is genetic engineering? Ans :

(a) Study of human anatomy Mendel chose the pea plant because it is bisexual,
(b) Technique to alter genetic constitution by can self-pollinate, and has distinct varieties with
introducing new genes contrasting characteristics.
(c) Observation of plants in natural habitat Thus (d) is the correct option.
(d) Study of animal behavior
28. Which of the following did Mendel achieve by
Ans : removing reproductive parts of the flower in pea
Genetic engineering involves modifying an plants?
organism’s genetic makeup by adding new genes (a) Improved plant growth
to its chromosomes. (b) Prevented self-pollination
Thus (b) is the correct option. (c) Enhanced genetic variation
(d) Increased flower size
24. Who is known as the “Father of Genetics”?
(a) Charles Darwin Ans :
(b) Gregor Johann Mendel By removing reproductive parts, Mendel
(c) Robert Hooke prevented self-pollination, allowing controlled
(d) Alexander Fleming cross-pollination for his experiments.
Thus (b) is the correct option.
Ans :l
Mendel is considered the Father of Genetics due 29. What role does variation play in species survival?
to his pioneering work on heredity using garden (a) It helps in species extinction
pea plants. (b) It increases chances of survival in changing
Thus (b) is the correct option. environments
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 51

(c) It makes all organisms identical Ans : SQP 2000

(d) It decreases genetic diversity Gregor Johann Mendel.

Ans : 37. The number of chromosomes in human
Variation increases adaptability, which can is______.
be critical for a species' survival in dynamic
Ans : COMP 2014
environmental conditions.
Thus (b) is the correct option. 46 (23 pairs)

38. The small differences among individuals are

called______.

ONE MARK QUESTIONS Ans : MAIN 2008

Variations

39. The dissimilar pairs of genes present in an

DIRECTION : Give appropriate biological/technical individual are known as ______
terms for the following:
Ans : MAIN 2017

30. A cross between one pair of contrasting characters. Heterozygous

Ans : MAIN 2015
40. ______ The chromosomes do not take part in
Mono-hybrid cross sex determination.

31. The type of gene, which in the presence of a Ans : COMP 2020

contrasting allele is not expressed. Auto-somes

Ans : SQP 2014, 2004
41. ______ Is the ratio of dihybrid cross.
Recessive gene
Ans : SQP 2003

32. The physical expression of genes in an individual. 9:3:3:1

Ans : COMP 2013
42. A character that is not suppressed is ______.
Phenotype
Ans : COMP 2019

33. A pair of chromosomes carrying dissimilar alleles Dominant gene

for a particular character.
43. Upon ______ the diploid condition is restored.
Ans : MAIN 2009
Ans : MAIN 2010
Heterozygous
Fertilisation
34. A pair of corresponding chromosomes of the same
size and shape, one from each parent. 44. Haemophilia is caused due to ______ gene.

Ans : SQP 2017 Ans : SQP 2015

Homologous chromosome Recessive

35. The condition in which a pair of chromosomes 45. ______is the scientific name of garden pea,
carry similar alleles of a particular character. which Mendel used for his experiment.

Ans : COMP 2018 Ans : COMP 2023

Homozygous Pisum sativum

46. The number of chromosomes in the human ovary

DIRECTION : Fill in the blanks is______.
Ans : MAIN 2004
36. ______is the Father of Genetics.
23
CH 2 : GENETICS

47. The alternative form of a gene is called______. Ans : COMP 2011

Ans : SQP 2007

False. Chromosomes other than the pair of sex
chromosomes are called autosomes.
Allele
56. The chemical substance present in gene is RNA.
48. ______is the genetically controlled observable
characteristics of an organism. Ans : SQP 2012

Ans : MAIN 2009

False. The chemical substance present in gene is
DNA.
Phenotype
57. When both the alleles are identical, they are said
49. ______is a sex-linked disease. to be homozygous.
Ans : SQP 2016 Ans : MAIN 2020
Colour blindness True.
50. The small differences among individuals are called 58. The genetic make up of an organism is phenotype.
______.
Ans : SQP 2018
Ans : COMP 2005
False. The genetic make up of an organism is
Variations genotype.

59. The two arms of a chromosome is called

DIRECTION : Rewrite and complete the following
centromere.
sentences by inserting the correct word in the space
indicated Ans : MAIN 2004

False. The two arms of a chromosome is called

51. ______ is alternate forms of genes. chromatids.
Ans : MAIN 2015
60. The plant used by Mendel is sweet pea.
Allele
Ans : COMP 2000
52. Phenotype is the observable characteristic which False. The plant used by Mendel is garden pea.
is ______ controlled.
61. When both the alleles are different, they are said
Ans : COMP 2011, 2010
to be homozygous.
Genetically
Ans : SQP 2008
53. ______ is the scientific name of garden pea, False. When both the alleles are different, they
which Mendel used for his experiments. are said to be heterozygous.
Ans : SQP 2015
62. The plant used by Mendel was sweet pea.
Pisum sativum is the scientific name of garden
pea, which Mendel used for his experiments. Ans : MAIN 2023

False. The plant used by Mendel was garden pea

54. The suppressed allele of a gene.
63. The number of chromosomes in man is 23.
Ans : MAIN 2017

Recessive allele Ans : SQP 2020

False. The number of chromosome in man is 46.

DIRECTION : State whether the following 64. Suppressed character is always the recessive
statements are True or False. If false, rewrite the character.
correct statement :
Ans : COMP 2016

55. Chromosomes other than the pair of sex True.

chromosomes are called alleles.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 53

DIRECTION : Give one point of difference between 70. Gene

the following on the basis of what is given in the
Ans : SQP 2013
bracket
A gene is the basic unit of heredity, and are
65. Genotype and Phenotype. (definition) located on chromosome.
or
71. Phenotype
Differentiate between genotype and phenotype.
Ans : SQP 2017
Ans : MAIN 2010, 2004
The physical appearance of an organism is called
Genotype is the genetic make up of an organism.
phenotype, e.g. dark colour, long hair, etc.
Phenotype is the external appearance of an
organism 72. Homologous chromosomes
Ans : MAIN 2010
DIRECTION : Give scientific reasons for the
following statements: A pair of corresponding chromosomes of the same
size and shape, one from each parent.
66. Colour blindness is more common in men than in
73. Variation
women.
Ans : COMP 2000
Ans : SQP 2016
Variations are the differences shown by individuals
It is due to recessive genes being present on X
of a species or offspring of the same parents.
chromosomes. As males have one X chromosome
only, so the genetic traits that are sex-related are 74. Law of dominance
easily seen in men than in women. Ans : MAIN 2005

Out of a pair of contrasting characters present

DIRECTION : Given below are groups of terms. In together in an offspring, one expresses while the
each group the first pair indicates the relationship other remains hidden. This law is called the law
between the two terms. Rewrite and complete the of dominance.
second pair on a similar basis.
75. Linkage
67. Example : Oxygen : Inspiration : : Carbon dioxide: Ans : SQP 2007

Expiration TT : Homozygous : : Tt :______ Linkage is the tendency of genes to stay together

Ans : COMP 2017 in hereditary transmission.
TT : Homozygous : : Tt : Heterozygous 76. Homozygous
Ans : MAIN 2002
DIRECTION : Define the following :
Homozygous is the condition in which both the
alleles are identical.
68. Alleles
or 77. Heredity
Define by giving an example : Allele.
Ans : MAIN 2020
Ans : MAIN 2012, 2003
The transmission of genetically based
The alternative forms of a gene for a character characteristics from the parents to the offspring.
producing different effects are called alleles. For
example, one allele of the gene for colour of hair 78. Genetics
produces black hair and another allele produces Ans : COMP 2012
brown hair.
Genetics is the branch of biology which deals
69. Monohybrid cross with the study of transmission of characters from
parents to offspring.
Ans : COMP 2014

It is a cross which is carried out by taking only 79. Trait

one pair of contrasting character at a time.
CH 2 : GENETICS
Ans : SQP 2001
Haemophilia
A quality or characteristic that can belong to only
a person. 88. The unit of heredity.
Ans : SQP 2001
80. Mutation
Genes
Ans : MAIN 2022

Mutation is the sudden change in a gene which 89. Number of pairs of autosomes in humans.
alters the hereditary materials of an organism. Ans : MAIN 2015

22 pairs
DIRECTION : Identify the odd term in following set
and name the category to which the remaining three 90. The condition in which both the alleles are
belong. identical
Ans : COMP 2010
81. Typhoid, Haemophilia, Albinism, Colour
Homozygous
blindness.
Ans : MAIN 2016 91. Monohybrid ratio.

Typhoid, all others are congenital genetic Ans : MAIN 2019

disorders. 3:1
82. Chicken pox, Colour blindness, Haemophilia, 92. The chemical substance which constitutes genes.
Albinism.
Ans : SQP 2008
Ans : COMP 2019
DNA
Chickenpox : others are hereditary traits/genetic
defects. 93. The sex chromosomes of male.
Ans : COMP 2003

DIRECTION : Name the following: X and Y

83. Father of Genetics. 94. The allele which expresses itself on the other.
Ans : SQP 2009
Ans : MAIN 2023
Dominant
Gregor Johann Mendel
95. One genetic disease.
84. The branch of science which deals with heredity.
Ans : MAIN 2001
Ans : COMP 2020
Haemophilia
Genetics
96. The genetic make up of an organism.
85. What is DNA? Ans : COMP 2017

Ans : SQP 2018 Genotype

The DNA is the chemical basis of gene. It controls
97. Two sex-linked inherited diseases.
all the biosynthetic processes of the cell.
Ans : SQP 2007

86. The chromosomes responsible for sex Haemophilia and colour blindness
determination.
98. The pair of genes responsible for a particular
Ans : MAIN 2011
characteristics in an individual.
Sex Chromosomes Ans : MAIN 2014

87. A hereditary disease in which blood does not clot. Alleles

Ans : COMP 2008 99. The plant on which Mendel had worked.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 55
Ans : SQP 2022
109. The dihybrid phenotypic ratio is ______ . (3 :
Garden pea (Pisum sativum). 1, 2 : 1, 1 : 2 : 1, 9 : 3 : 3 : 1)

100. A sudden heritable change in the gene. Ans : SQP 2006

9:3:3:1
Ans : MAIN 2009

Mutation. 110. Which of the following is the genetic X-linked

disease? ______. (Haemophilia, Painting,
101. The scientific name of garden pea. Black Hair, Singing)
Ans : COMP 2020 Ans : MAIN 2007

Pisum sativum Haemophilia

102. Two sex linked inherited diseases.
DIRECTION : Give one point of difference between
Ans : SQP 2013
the following on the basis of what is given in the
Colourblindness and Haemophilia bracket:
103. The chemical substance which constitutes genes.
111. Pure and Hybrid strains. (Definition)
Ans : COMP 2023
Ans : SQP 2020
Deoxyribonucleic acid
Pure strains : An organism with same characters
104. The second law of Mendel. as that of the parents, e.g. for red flower
(RR) Hybrid strains : Organisms with dual
Ans : SQP 2002
characteristics, e.g. (Rr)
Law of Independent Assortment
112. Phenotype and Genotype.
105. An alteration in genetic material that can be
Ans : MAIN 2023
inherited.
Phenotype : The characters which are visible
Ans : MAIN 2010
from outside in an organism.
Mutation Genotype : The characters which are not visible
from outside in an organism.

113. Give an example of an established genetic trait in

DIRECTION : Choose the correct option from the
human being.
brackets :
Ans : COMP 2005

106. The chemical substance which constitutes the Colour blindness.

gene is______ (RNA, DNA, ATP, ADP).
114. What is genome?
Ans : SQP 2017
Ans : MAIN 2006
DNA
It is the full complement of DNA in an organism.
107. The number of pairs of autosomes in humans 115. A dog and a chicken have 78 chromosomes.
is______ (19, 22, 23, 46). But they are different from each other in many
Ans : MAIN 2011 aspects. Why?
22 Ans : SQP 2017

Though they have the same number of

108. The process .of producing genetically identical
chromosomes, the variations are due to the
organism from a single parent is called______.
presence of genes on the chromosomes.
(linkage, variation, cloning, mutation)
Ans : COMP 2019 116. Gametes are always pure. Comment.
Cloning Ans : MAIN 2009
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CH 2 : GENETICS

Gametes are generally sex cell that are either egg whereas only one X-chromosome is present in
or sperm. They are pure because they are always males, hence a single gene expresses it.
haploid.
124. (i) State Mendel’s law of dominance.
117. What is meant by emasculation in plants? (ii) State Mendel’s law of segregation.
Ans : COMP 2004 Ans : MAIN 2025 , 2015

Emasculation is a process used in plant breeding. (i) Law of Dominance : Out of a pair of
It is done to remove anthers from bisexual flowers contrasting characters present together in an
without disturbing the pistil of the flower. offspring, one dominates over the other.
(ii) Law of Segregation (First Law of Mendel)
118. What is the difference between monohybrid and : The contrasting factors or characters
dihybrid cross (Phenotypic ratio) ? (alleles) separate during gamete formation.
Ans : SQP 2016 At the time of zygote formation, the gametes
combine randomly but alleles or characters
Monohybrid phenotypic ratio = 3 : 1
do not blend and separate during gamete
Dihybrid phenotypic ratio = 9 : 3 : 3 : 1
formation.
119. What are autosomes ?
125. In a certain species of animals black fur (B) is
Ans : MAIN 2023 dominant over brown fur (b). Predict a genotype
The chromosomes that do not have genes for sex and phenotype of the offspring when both parents
determination are called autosomes. are Bb or have heterozygous black fur.
Ans : MAIN 2004
120. What is a phenotype ?
Ans : SQP 2021

The observable characteristics of an organism that

are genetically controlled is called phenotype.

121. Define variations.

Ans : MAIN 2006
126. What is genetic disease? Name two genetic
The differences which occur in closely related diseases.
organisms are called variations.
Ans : MAIN 2017

122. If a color blind man marries a woman with normal Sex-linked human traits are mostly on X
vision, what will be the nature of their children ? chromosomes. Most of these concern human
Ans : COMP 2003 diseases are carried by recessive genes. Haemophilia
and colour blindness are the two genetic diseases.
Their daughter will be a carrier of colourblindness
but their son will have normal vision. 127. Explain the structure of a chromosome.
Ans : SQP 2023

At metaphase, chromosome during cell division

TWO MARKS QUESTIONS condense and then undergo replication. Each
chromosome consists of two identical replication
called chromatids that are joined at a point
123. Give scientific reason for the statement Colour called centromere. Chromosome contain genes,
blindness is more common in men than in women. responsible for transmission of characters from
Ans : COMP 2016
one generation to another generation.

Colorblindness is more common in men as 128. (i) Name the type of genes, which in the presence
compared to women because it is a sex-linked and of a contrasting allele, is not expressed.
recessive trait. It need two alleles for its expression (ii) Name two animals which have nineteen pairs
in women as she contains 2 X-chromosomes of chromosomes.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 57
Ans : COMP 2010
THREE MARKS QUESTIONS
(i) Recessive
(ii) Cat, sheep. 133. Answer the following :
129. What is a pure strain and how it is different from (i) What is DNA?
a hybrid strain ? (ii) State the difference between autosomes and
sex chromosomes.
Ans : COMP 2018 (iii) Mutation
The self pollinated progeny of a homozygous Ans : MAIN 2015
plant is a pure strain while offspring of genetically
dissimilar parents is a hybrid strain. These (i) The DNA is the chemical basis of gene. It
offspring are obtained by artificial pollination. controls all the biosynthetic processes of the
cell.
130. The sex of the child depends upon its father. (ii)
Explain.
Autosomes Sex Chromosomes
Ans : SQP 2017
(i) They do not (i) They determine
Sex chromosomes of female are homozygous (XX) participate in sex the sex of an
while in male it is heterozygous XY. If a sperm determination. individual.
bearing X chromosome fertilizes with the ovum,
(ii) They are of one (ii) They are of two
XX zygote formed is a female child. If a sperm
type. types : X and Y.
bearing Y chromosome fertilizes with the ovum,
XY zygote formed, i.e. a male child. So the sex of (iii) Mutation : The sudden change in one or more
a child depends upon its father. genes, which change the hereditary materials
of an organism and ultimately change the
131. A pure tall plant bearing red coloured flowers character of an organism. It may be :
was crossed with a pure dwarf plant with white (a) Gene Mutation : Changes in the DNA,
flowers. What would be the nature of offspring in Sickle-cell anemia is caused due to gene
the F1 generation? mutation where chemical changes occur
Ans : MAIN 2011 in the DNA.
(b) Chromosomal Mutation : Changes
In the F1 generation, all plants will be tall and
in the number or arrangement of the
bear red coloured flowers, i.e.
chromosome. Chromosomal mutation
are the changes in the arrangement
on number of chromosomes as seen in
Down’s syndrome.

134. Why did Mendel select garden pea for his

experiments?
Ans : SQP 2014

He selected garden pea because

(a) Pea plant has bisexual flowers.
132. How is sex determined in humans? (b) Many varieties were available in alternative
Ans : SQP 2002 forms.
(c) It is an annual plant.
In humans, the male contains X and Y sex
(d) The varieties were in pure forms that bred
chromosomes and the female contains XX
true.
chromosomes. If the sperm bearing the X
(e) It was easily available.
chromosome fertilizes the ovum, the zygote is
(f) It has a short life cycle.
XX, i.e. a female child. If the sperm bearing Y
(g) Handling the plant was easily.
chromosome fertilizes the ovum, the zygote is XY,
(h) Large number of off-springs were produced in
i.e. a male child.
a single generation.
(i) It could be easily artificially pollinated and
the hybrids produced were fertile.
CH 2 : GENETICS

135. In a certain species of animals black fur (B) is (ii) Genetics (d) The study of
dominant over brown fur (b). Predict a genotype inheritance of
and phenotype of the offspring when both parents characters.
are Bb or have heterozygous black fur.
(iii) Sex (e) Determine the sex of
Ans : COMP 2009 chromosomes a child.
(iv) Mutation (b) Sudden change in a
gene.
(v) Homologous (a) Similar
chromosomes chromosomes of the
same shape and size.

137. (i) Explain the following terms :

1. Monohybrid cross, 2. Gene, 3. Phenotype
(ii) Name the two sex-linked diseases in males.
(iii) State Mendel’s law of segregation.
Ans : SQP 2009

(i) 1. Monohybrid cross : A cross or breeding

between two individuals having one
Phenotype : Black –3/4 pair of contrasting traits producing all
Brown–1/4 hybrid (heterozygous) generation for that
Genotpe : BB (Homozygous black)–1/4 character.
2. Gene : These are the specific parts of
Bb (Homozygous black)–2/4
a chromosome (DNA segments), which
bb (Homozygous brown)–1/4 determine the heredity characters.
3. Phenotype : The morphological
136. Match the following Column : (observable) expression of any character
of an individual.
Column A Column B
(ii) (1) Colourblindness
(i) Dominant (a) Similar chromosomes
(2) Haemophilia
gene of the same shape
(iii) Mendel’s law of segregation states that the
and size.
two factors or genes controlling one character
(ii) Genetics (b) Sudden change in a separate or segregate without blending or
gene. influencing each other during the formation
(iii) Sex (c) The expressed gene of gametes so that each gamete receives one
chromosomes of an allele. factor or gene for each character.
(iv) Mutation (d) The study of 138. The figure shows sex determination in humans.
inheritance of
characters.
(v) Homologous (e) Determine the sex of
chromosomes a child.

Ans : MAIN 2004

Column A Column B
(i) Dominant (c) The expressed gene
gene of an allele.
(i) What are the right substitutes for the
numbers 1 to 6 ?
(ii) What is the sex of individuals represented by
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 59

numbers 3, 4, 5 and 6 ? Therefore, there are 50% chance of the child being
(iii) Who is responsible for the sex of offspring - a boy or a girl.
male or female ? Why ? 141. A pea plant with pure yellow (YY) round (RR)
Ans : COMP 2012 seeds were crossed with a plant having pure green
(yy) wrinkled (rr) seeds.
(i) 1 – X 2–Y 3 – XX
(i) What would be the nature of the offspring in
4 – XY 5 – XX 6 – XY
the F1 generation ?
(ii) 3 – female 4 – male
(ii) If the offspring of the F1 generation are self
5 – female 6 – male
pollinated what would be the phenotypic
(iii) Males are responsible for the sex of offspring
ratio in F2 generation ?
because males have X and Y chromosomes,
(iii) Which law is illustrated in part (ii)?
if this Y chromosome combines with X
chromosome of female, a male child results Ans : MAIN 2008
if X chromosome combines with other X (i) F1 offspring will be all yellow round.
chromosome, female child results. (ii) Yellow round : Yellow wrinkled : Green round
139. Find out the progeny of a marriage between a : Green wrinkled = 9 : 3 : 3 : 1
normal man and a carrier haemophilic woman. (iii) Law of independent assortment.
142. Distinguish between:
Ans : MAIN 2006
(i) Dominant allele and recessive allele.
(ii) Mono-hybrid and di-hybrid cross.
Ans : MAIN 2020

(i)

Dominant allele Recessive allele

(a) Similar pair of (a) Dissimilar pair of
chromosomes. chromosomes.
(b) The expressed (b) The suppressed
allele. allele.
(ii)

Monohybrid cross Dihybrid cross

140. There is a 50-50% chance for getting a male or Cross which is carried Across which is carried
female child. Justify. out by taking only one out by taking two pairs
pair of contrasting of contrasting character
Ans : SQP 2006
character at a time. at a time.
The sex of a child depends upon the kind of sperm
that fertilises the egg. Made sperm has X and Y 143. The figure shows a family pedigree to show the
chromosomes while females have X chromosomes inheritance of haemophilia.
only. If a sperm bearing an X chromosome fuses
with the egg, the child is a daughter (XX) and if
sperm bearing Y-chromosome fuses with the egg,
the child is a son (XY).

(i) Is the allele for haemophilia dominant or

recessive ?
(ii) State with reasons the genotype of individuals
1,2 and 4.
CH 2 : GENETICS

(iii) What are the possible genotypes of individuals (ii) Daughters as the trait is sex linked inheritance.
3 and 5 ? However the daughters are only the carrier of
the gene with normal visions. Normally, only
Ans : MAIN 2000
male show colour blindness.
(i) Recessive (iii) Colour blindness is a sex-inherited disease in
(ii) Individuals 1 and 2 are heterozygous since which a person cannot discriminate between
they are normal but produced an affected certain colours such as red and green. It is
child. Individual 4 is homozygous recessive due to a recessive gene on X chromosome. It
since the allele is recessive and individual can be explained by the given charts:
must have two copies of the allele to be Case - I
affected.
(iii) Individual 3 and 5 are normal but the
information presented is not sufficient to
determine whether they are homozygous
dominant or heterozygous.

144. Find out the progeny of a marriage between a

colour blind man and a carrier woman.
Ans : COMP 2001

All the male offspring have normal vision but

daughters are carriers.
Case - II

145. A family consists of two parents and they have

five children. The pedigree chart below shows
the inheritance of the trait of colour blindness in
them.

The colour blindness is inherited by the son

if mother is the carrier of the recessive gene.
Therefore, it is called sex-linked inheritance as
the gene is passed from mother to son or from
father to daughter.

146. If a homozygous pure tall plant (T) is crossed

with a homozygous pure dwarf plant (t), what
(i) Name the colour blind parent-mother or
will be the appearance of :
father.
(i) F1 progenies
(ii) How many children are born that have colour
(ii) F2 progenies
blindness?
(iii) What about the other children? Explain. Ans : SQP 2004

Ans : COMP 2015 Homozygous (pure) tall plant is designated as –

TT
(i) Father.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 61

Homozygous (pure) dwarf plant is designated as 3. Crosses involve 3. Crosses involve

– tt a single pair of two pair of alleles.
(i) A cross between homozygous tall parent and alleles.
homozygous dwarf parent will be :

FIVE MARKS QUESTIONS

148. In a homozygous pea plant, axial flowers (A) are

dominant over terminal flowers (a).
(i) What is the phenotype and genotype of the
F1 generation if a plant bearing pure axial
flowers is crossed with a plant bearing pure
The progenies of Fl generation will be all terminal flowers?
heterozygous tall (hybrids) (ii) Draw a Punnett square board to show the
(ii) The F1 hybrids are self pollinated and crossed gametes and off-springs when both the parent
to produce F2 progenies as follows : plants are heterozygous for axial flowers.
Three plants will be tall and one plant will (iii) What is the phenotypic ratio and genotypic
be dwarf in F2 generation. Out of three tails ratio of the above cross shown in (ii)?
one will be homozygous and two will be (iv) State Mendel’s Law of Dominance.
heterozygous. (v) Name two genetic disorders commonly seen in
human males.
Ans : SQP 2017

(i) Phenotype – Axial flowers

Genotype – Aa
(ii) Heterozygous Heterozygous

147. Give any three points of difference between

monohybrid and dihybrid cross.
Ans : SQP 2019

The difference between monohybrid and dihybrid

cross are as follows :
(iii) Phenotype ratio: 3 axial flower : 1 terminal
Monohybrid cross Dihybrid cross flower (3 : 1)
Genotype ratio: 1 AA : 2 Aa : 1 aa (1 : 2 : 1)
1. It yields a 1. It yields a (iv) Law of Dominance states that out of a pair of
phenotypic ratio phenotypic ratio of contrasting characters present together, one
of 3 : 1 in F2 9 : 3 : 3 : 1 in F2 express itself while the other remain hidden.
generation. generation. (v) 1. Colour blindness,
2. Law of 2. Law of 2. Haemophilia
independent independent
assortment is not assortment is 149. (i) State Mendel’s Law of Dominance.
applicable. applicable. (ii) A pure tall plant (TT) is crossed with a pure
dwarf plant (tt). Draw Punnett squares to
show (1) F1 generation (2) F2 generation.
(iii) Give the Phenotype of the F2 generation.
CH 2 : GENETICS

(iv) Give the Phenotypic and Genotypic ratio of (iv) Mention the phenotypes of the offsprings
the F1 and F2 generation. obtained in F2 generation.
(v) Name any one X-linked disease found in (v) What is the phenotypic ratio obtained in F2
humans. generation?
Ans : MAIN 2010 Ans : COMP 2016

(i) When two homozygous parents with a pair

of contrasting characters are crossed, the
characters that appear in the first generation
are dominant characters and those that do
not appear in the first generation are recessive
characters.

(i) Genotype – TtRr

Phenotype – Tall red
(ii) Gametes – TR, Tr, tR, tr
(iii) When two pairs of contrasting characters are
crossed, the distribution of the members of
one pair into the gametes is independent of
the distribution of the other pair.
(iv) Phenotypes – Tall red, Tall white, Dwarf red,
Dwarf white
(v) Phenotypic ratio = 9 : 3 : 3 : 1.
(iii) Phenotype of F2 generation
Tall plant–3/4 151. A homozygous plant having round (R) and yellow
Dwarf plant –1/4 (Y) seed is crossed with homozygous plant having
(iv) wrinkled (r) and green (y) seeds:
(i) Give the scientific name of the plant on
which Mendel conducted his hybridization
experiments.
(ii) Give the genotype of the F1 generation.
(iii) Give the dihybrid phenotypic ratio and the
phenotype of the offspring of the F2 generation
(v) Haemophilia/Colour blindness when two plants of the F1 generation are
crossed.
150. A homozygous tall plant (T) bearing red coloured (iv) Name and state the law which explains the
(R) flowers is crossed with a homozygous dwarf dihybrid ratio.
(t) plant bearing white (r) flowers: (v) Give the possible combinations of gametes
(i) Give the genotype and phenotype of the that can be obtained from F1 hybrid.
plants of F1 generation.
Ans : COMP 2012
(ii) Mention the possible combinations of the
gametes that can be obtained from the F1 (i) Pisum sativum
hybrid plant. (ii) RrYy
(iii) State the Mendel’s law of Independent (iii) Dihybrid phenotypic ratio 9 : 3 : 3 : 1
Assortment. The phenotypes are round, yellow ; wrinkled
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 63

yellow ; round green and wrinkled green. Ans : MAIN 2015

(iv) Law of Independent Assortment states that (i)

if the inheritance of two pairs of characters is
studied, the factors for each pair of characters
assort out independent of the other pair.
(v) RY, Ry, rY, ry

152. Given below is a schematic diagram showing

Mendel’s Experiment on sweet pea plants having (ii) Phenotype ratio : 3 : 1
axial flowers with round seeds (AARR) and Genotype ratio : 1 : 2 : 1
terminal flowers with wrinkled seeds (aarr). Study (iii) Human male : XY chromosomes
the same and answer the questions that follow: Human Female : XX chromosomes
(iv) A sudden change in one or more genes which
alters the hereditary materials of an organism.
(v) 23 chromosomes.

154. In Mendel’s experiments, tall pea plants (T) are

dominant over dwarf pea plants (t).
(i) What is the phenotype and genotype of the
F1 generation if a homozygous tall plant is
crossed with a homozygous dwarf plant ?
(ii) Draw a Punnett square board to show the
gametes and offspring when both the parents
(i) Give the phenotype of F1 progeny. are heterozygous for tallness.
(ii) Give the phenotypes of F2 progeny produced (iii) What is the phenotypic ratio and genotypic
upon by the self-pollination of F1 progeny. ratio of the above cross in (ii)?
(iii) Give the phenotypic ratio of F2 progeny. (iv) State Mendel’s Law of Dominance.
(iv) Name and explain the law induced by Mendel (v) What is a Dihybrid Cross ?
on the basis of the above observation. Ans : COMP 2019

Ans : SQP 2013 (i) Phenotype of F1 generation is all are tall

(i) Axial flowers with round seeds. plants. Genotype of F1 generation is all plants
(ii) Axial round, Axial wrinkled, Terminal round, are Tt.
Terminal wrinkled. (ii) Punnett square is as follows :
(iii) 9.3.3.1
(iv) Law of independent assortment – When
there are two pairs of characters, then the
distribution of each pair to the gametes is
independent of the distribution of the other
pair of character.

153. In a homozygous plant, round seeds (R) are (iii) Phenotypic ratio = 3 : 1
dominant over wrinkled seeds (r): Genotypic ratio = 1 : 2 : 1
(i) Draw a Punnett square to show the gametes (iv) In a heterozygous condition, out of the
and offspring when both the plants have two contrasting alleles, one expresses
heterozygous round seeds (Rr). itself morphologically and other remains
(ii) Mention the Phenotype and Genotype ratios unexpressed. The factor which expresses
of the off-springs in F2 generation. itself phenotypically is called dominant and
(iii) Name the sex chromosomes in human males the other which remains unexpressed is called
and females. recessive.
(iv) Briefly explain the term ‘Mutation’. (v) A cross between two individuals having
(v) What is the number of chromosomes in the two pairs of contrasting traits producing
gametes of human beings? a generation in which all individuals are
heterozygous for both the characters.
CH 2 : GENETICS

155. Define the following : (ii) Phenotype:-

(i) Genetics 9:3:3:1
(ii) Genetic engineering Genotype :-
(iii) Genes
(iv) Genome RRYY - 1 RrYY - 2 rrYY - 1
(v) Alleles RRYy - 2 RrYy - 4 rrYy - 2
(vi) Punnett square RRyy - 1 Rryy - 2 rryy - 1
Ans : SQP 2018
(iii) The name of sex chromosomes in human
males and females is Allosomes/Idiosomes.
(i) Genetics : Genetics is the study of transmission (iv) Mutation is a sudden change in one or
of body features (both similarities and more gene or in the number and structure
differences) from parents to offspring and the of chromosomes in the progeny causing
laws related to such transmission. changes in certain traits, which may not have
(ii) Genetic engineering : is the technique in existed in parents, grandparents or even great
which the genetic constitution of an organism grandparents.
(bacterium) is altered by introducing new (v) The number of chromosomes in the gametes
genes into its chromosomes. of human beings is 46.
(iii) Genes : Genes are the specific parts (DNA
segments) of a chromosome, which determine 157. A pea plant which is homozygous for Green
the hereditary characters. pods which are inflated [GGII] is crossed with
(iv) Genome : It is the full complement of DNA a homozygous plant for yellow pods which are
(including all genes and the intergenic constricted [ggii]. Answer the following questions:
regions). (i) Give the phenotype and genotype of the F1
(v) Alleles : Alternative forms of gene, occupying generation.
the same position on homologous chromosomes Which type of pollination has occurred to
and affecting the same characteristics but in produce F1 generation?
different ways. (ii) Write the phenotypic ratio of the F2
(vi) Punnett square : It is a simple diagram in generation.
which the different types of gametes (sex (iii) Write the possible combinations of the
cells with the concerned trait) of one (female) gametes that can be obtained if two F1 hybrid
parent are placed along one side of the square plants are crossed.
and those of the other parent (male) are (iv) State Mendel’s law of ‘Segregation of
placed along the other side. Gametes’.
(v) What is the scientific name of the plant
156. In a homozygous plant round seeds (R) are which Mendel used for his experiments on
dominant over wrinkled seeds (r) : inheritance?
(i) Draw a Punnett square to show the gametes
and offspring when both the plants have Ans : SQP 2018

heterozygous round seeds (Rr). (i) Phenotype of F1 generation – All plants with
(ii) Mention the Phenotype and Genotype ratios green coloured pods and with inflated pod
of the offsprings in F2 generation. shape Genotype of F1 generation – All plants
(iii) Name the sex chromosomes in human males with GgIi Cross pollination.
and females. (ii) 9 : 3 : 3 : 1
(iv) Briefly explain the term ‘Mutation’. (iii) Possible combinations of gametes are as
(v) What is the number of chromosomes in the follows GI, Gi, gI, gi
gametes of human beings? (iv) The two factors or genes controlling one
Ans : MAIN 2020
character separate or segregate without
blending or influencing each other during the
(i) The Punnett square is as follows: formation of gametes so that each gamete
receives one factor or gene for each character.
R r or
R RR Rr Two members of a pair of factors separate
during the formation of gametes.
r Rr rr
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 65

(v) Pisum sativum flowers (r):

(a) Give the Genotype and Phenotype of the
158. (i) State Mendel’s Law of Dominance. F1 generation.
(ii) A pure tall plant (TT) is crossed with a pure (b) Give the possible combinations of the
dwarf plant (tt). gametes that can be obtained from the F1
Draw Punnett squares to show (1) F1 hybrid.
generation (2) F2 generation. (c) Give the dihybrid ratio and the phenotype
(iii) Give the phenotype of the F2 generation. of the off-springs of the F2 generation
(iv) Give the Phenotypic and Genotypic ratio of when two plants of the F1 generation
the F1 and F2 generation. above are crossed.
(v) Name any one X-linked disease found in
humans. Ans : COMP 2015

Ans : SQP 2021

(i) When there are two pairs of contrasting
characters, then the distribution of each
(i) Law of Dominance : Out of a pair of pair to the gametes is independent of the
contrasting characters present together, only distribution of the other pair of characters.
one is able to express itself while the other (ii)
remain unexpressed. The one that expresses
itself is the dominant character and the one
unexpressed is recessive.
(ii)

(iii) Phenotypes of F2 generation are both tall and

dwarf.
(iv) F1 generation, all plants are tall with similar (a) Genotype – TtRr (Heterozygous tall red).
genotype Tt. Phenotype – Tall plant, red flowers.
F2 generation phenotypic ratio is 3 tall : 1 (b) TR, Tr, tR and tr
dwarf. (c) Dihybrid ratio = 9 : 3 : 3 : 1
F2 generation genotypic ratio is 1 TT : 2 Tt Phenotype of the offsprings:
: 1 ft Tall plant, red flowers = 9
(v) Haemophilia, colourblindness. Tall plant, white flowers = 3
Dwarf plant, red flowers = 3
159. (i) State Mendel’s law of Independent Dwarf plant, white flowers = 1
Assortment.
(ii) A homozygous tall plant (T) bearing red
coloured (R) flowers is crossed with a
homozygous dwarf plant (t) bearing white
CH 2 : GENETICS
Ans :
CASE BASED QUESTION
1. Males are more affected because they have
only one X chromosome, so the abnormal
160. In a biology class, the teacher explained how gene isn't masked.
genetics plays a crucial role in determining the 2. The wife has a 50% chance of passing the
characteristics of living organisms. She discussed abnormal gene to her children.
how traits like eye color, hair type, and even 3. Sons have a 50% chance of inheriting
certain behaviors can be inherited from parents colorblindness if they receive the abnormal X
and passed down to offspring. The students were from their mother.
asked to observe similarities and differences in 4. A daughter would need abnormal genes from
traits among family members and discuss how both parents to inherit colorblindness.
variations arise even within the same family.
1. How does genetics influence the transmission 162. Dr. Meera's genetics team studies mutations and
of traits from parents to offspring? their effects. They focus on gene mutations like
2. Why do variations in traits occur among sickle cell anemia and chromosomal mutations like
family members, even when they share the Down's syndrome. They also use Ishihara cards to
same genetic material? detect colorblindness and observe traits in hybrids
3. What role does heredity play in the like Hebras and Ligers from crossbreeding.
development of physical features like eye 1. What is the difference between gene and
color and hair type? chromosomal mutations?
4. How can studying family traits help us 2. How is colorblindness detected?
understand the laws of heredity better? 3. How do mutations cause diseases like sickle
cell anemia and Down’s syndrome?
Ans : 4. How does crossbreeding affect hybrid traits?
1. Genetics determines how traits are passed Ans :
from parents to offspring through genes.
2. Variations occur due to genetic recombination 1. Gene mutations affect individual genes, while
and mutations, leading to differences even in chromosomal mutations involve chromosome
the same family. changes.
3. Heredity controls the transfer of traits like 2. Colorblindness is detected using Ishihara
eye color and hair type through genes passed cards.
from parents. 3. Mutations alter DNA, leading to diseases like
4. Observing family traits helps us understand sickle cell anemia and Down’s syndrome.
patterns of inheritance and how genes 4. Crossbreeding results in hybrids with traits
function in transmitting characteristics. from both parents.

161. A genetic counselor is advising a couple where 163. Priya, a research student, is studying sex-
the husband has colorblindness, and the wife’s linked inheritance. She learns that disorders
father had the condition. The counselor explains like colorblindness and hemophilia are linked
that colorblindness is an X-linked recessive trait. to the X chromosome and are more common
Since the wife is not colorblind, she likely carries in males. Additionally, she finds that traits
one normal gene and one abnormal gene. The like hypertrichosis (long hair on the pinna) are
couple wants to know the chances of passing Y-linked, affecting only males.
colorblindness to their children. 1. Why are disorders like hemophilia more
1. Why is colorblindness more common in males common in males than females?
than females? 2. What type of gene carries hypertrichosis, and
2. How might the wife’s genetic background who does it affect?
affect their children's chances of inheriting 3. How does the presence of a single X
colorblindness? chromosome influence sex-linked traits in
3. What is the likelihood of their sons inheriting males?
colorblindness? 4. Name two X-linked disorders Priya studied in
4. Why would a daughter be less likely to inherit her research.
colorblindness? Ans :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 67

1. Disorders like hemophilia are more common Ans :

in males due to their single X chromosome. 1. Sickle cell anemia is caused by a gene
2. Hypertrichosis is carried on the Y chromosome mutation.
and affects only males. 2. Down syndrome is caused by a chromosomal
3. A single X chromosome in males allows mutation.
recessive traits to express more easily. 3. Mutations alter an individual’s genetic
4 Priya studied colorblindness and hemophilia structure, affecting traits.
as X-linked disorders. 4. Chemical or structural changes can cause
mutations in a gene or chromosome
164. Arun is studying Mendelian inheritance in his
biology class. He learns that traits are determined www.nodia.in
by alleles, with dominant alleles masking recessive
ones. For example, brown eyes are dominant over
blue eyes. Arun sets up an experiment with pea
plants to observe the Law of Segregation and
the Law of Dominance by crossing plants with
different traits.
1. What does the Law of Dominance state about
alleles in a heterozygous condition?
2. Which eye color is dominant, according to
Arun’s study?
3. What does the Law of Segregation explain
about allele separation?
4. What is the observable outcome called in
genetics?
Ans :
1. The Law of Dominance states that the
dominant allele expresses itself in a
heterozygous condition.
2. Brown eye color is dominant over blue,
according to Arun’s study.
3. The Law of Segregation explains that alleles
separate independently during gamete
formation.
4. The observable outcome in genetics is called
the phenotype.

165. Nisha is studying genetic mutations and learns

that mutations can affect a single gene or an
entire chromosome. She examines examples like
sickle cell anemia, caused by a gene mutation, and
Down syndrome, resulting from a chromosomal
mutation. Nisha notes how these mutations
impact individuals differently based on their
genetic structure.
1. What type of mutation causes sickle cell
anemia?
2. Which syndrome is caused by a chromosomal
mutation according to Nisha's study?
3. How do mutations impact an individual’s
genetic structure?
4. What can cause a change in a single gene or
chromosome?
CH 3 : ABSORPTION BY ROOTS

CHAPTER 3
ABSORPTION BY ROOTS

1. INTRODUCTION
Water is the major constituent of living beings.
It is the medium in which all cellular reactions
take place. It has physical properties such as high
specific heat, high heat of vaporization, expansion
upon freezing, cohesion and adhesion.
Roots absorb water and minerals from soil and
help in ascent of sap (upward movement of water
and dissolved minerals).
Water is the basic necessity of all life and plants
specially need water as it helps in photosynthesis,
transpiration, transportation, turgidity, cooling,
opening of stomata and germination of seeds. 3. IMBIBITION
Mineral nutrients are essential for the growth and It is the movement of water molecules into
metabolic activities of plant cells. These are taken substances such as wood, seeds, agar or gelatin,
up by roots in the form of ions and radicals. which swell or increase in volume as a result
of this movement. These substances are called
2. NEED OF MINERALS FOR PLANTS imbibants.
The following minerals are required for plants : Imbibition of water increases the volume of
1. Magnesium – Essential for synthesis of the imbibant due to which tremendous pressure is
chlorophyll. created which is known as imbibitional pressure.
2. Zinc – Essential for leaf formation.
3. Calcium – Maintains semi-permeability of cell 4. DIFFUSION
membrane. It is the movement of molecules of various substances
4. Potassium – Maintains osmotic balance of cell from the region of their higher concentration
and controls opening and closing of stomata. to the region of their lower concentration by
5. Phosphorus – Constituent of cell membrane random movement of the molecules or ions of
and promotes cell division. the substance. This movement continues till the
6. Manganese – Necessary for photolysis of concentration of molecules become same in all
water in photosynthesis. available space. The force responsible for diffusion
7. Nitrogen – Required for protein synthesis and of molecules is their kinetic energy.
hence growth. In a cell, diffusion spreads molecules and ions,
throughout its protoplasm.
2.1 Characters of Roots for Absorbing Water
1. Extensive root hairs with rapid growth. 4.1 Diffusion Pressure
2. Enormous surface area. It is the pressure exerted by the diffusing particles
3. High concentrated solution of root hairs and is directly proportional to their concentration.
because of the presence of a large vacuole Higher the concentration of diffusing particles,
filled with cell sap. greater is the diffusion pressure.
4. Thin walls of root hairs.
4.2 Rate of Diffusion
Though diffusion is a slow process, the rate of
diffusion is faster if :
1. The difference in concentration between
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 69

the two regions (concentration gradient) is 3. Hypertonic solution

increased.
2. The distance between the two regions 7. TURGIDITY
decreased. A cell when reaches a state where it cannot
3. The molecules diffusing are small and fat accommodate any more water (fully distended
soluble. condition), when it is kept in a hypotonic solution
4. The area over which diffusion occurs is is called turgidity and the state of the cell is called
increased. as turgid.
5. The number of pores in the cell membrane is Turgidity of cells is essential for the plant to live
large and their size is greater. and grow normally. It provides rigidity to plants
such as stretching of shoots, keeping leaves erect
4.3 Diffusion in Our Daily Life and fully expanded.
When sugar is put in a liquid, its molecules Drooping of leaves on touching is brought by the
diffuse throughout the liquid, giving it uniformly changes in turgidity of the cells of pulvinus of
a sweet taste. The fragrance of perfume from an Mimosa pudica (touch me not plant).
open bottle also reaches us through the process
of diffusion. 7.1 Turgor Pressure and Wall Pressure
The hydrostatic pressure developed inside a cell
4.4 Diffusion Observed in Plants on the cell wall due to endosmosis is called turgor
It helps in exchange of gases during photosynthesis pressure and the pressure exerted by the cell wall
and respiration. In transpiration, water vapours on the cell content is called wall pressure.
diffuse from the intercellular spaces to the outer Turgor pressure and wall pressure normally
atmosphere. During the passive salt uptake, ions counter balance each other and a state of
are absorbed by the simple process of diffusion. equilibrium is maintained.

5. OSMOSIS 8. PLASMOLYSIS
It is the movement of water molecules from In plant cells, placed in hypertonic solution,
the region of their higher concentration to the water escapes from the vacuoles of the cell by
region of their lower concentration through a exosmosis. First, the cell becomes flaccid, with
semipermeable membrane. further loss of water, the protoplast shrinks away
from the cell wall, often assumes a spherical shape
5.1 Osmotic Pressure and ultimately comes to lie in the centre of the
Osmotic pressure of a solution is that pressure cell. The shrinkage of the cytoplasm along with
which would be required to prevent it from gaining the plasma membrane from the cell wall under
more solvent molecules if it is separated from the the action of a hypertonic solution is called as
solvent by a differentially permeable membrane. plasmolysis.

5.2 Types of Membranes 8.1 Importance of Plasmolysis

1. Permeable membrane, e.g. cell wall, muslin It proves permeable nature of cell wall and
cloth. semipermeable nature of plasma membrane. It
2. Impermeable membrane, e.g. rubber sheet. also helps in determining the osmotic pressure of
3. Semipermeable membrane, e.g. parchment a cell and that whether a particular cell is living
paper, sheeps or goats bladder, cellophane or dead.
paper, egg membrane, visking bag. High concentration of sugar in jams and jellies
4. Differentially permeable membrane, e.g. cell protect them from decay by bacteria and fungi
membrane. due to plasmolysis.

6. TONICITY 9. DEPLASMOLYSIS
It is the amount of tension developed in a system The phenomenon of absorption of water by a
on account of solute particles on it. plasmolysed cell through endosmosis is called as
The solutions are of three types : deplasmolysis.
1. Isotonic solution
2. Hypotonic solution
CH 3 : ABSORPTION BY ROOTS

10. ROOT PRESSURE

MULTIPLE CHOICE QUESTION
It is the pressure developed in the xylem of roots
due to inflow of water, which helps in pushing the
plant sap upwards. Root pressure is built up due 1. During a practical exam, a plant cell in a
to cell to cell osmosis in the root tissue. particular solution was placed under a compound
microscope. Students were told to observe the cell
11. ASCENT OF SAP
and name the tonicity of the solution and mention
The upward transport of water (along with the process that occurred in the cell.
dissolved inorganic mineral salts) from roots to
aerial parts of the plant is called ascent of sap.
This process occurs in plants through xylem tissue
which are continuous and forms an unbroken
system of tubes. Ascent of sap is due to root
pressure, cohesion, adhesion, transpiration pull
and capillarity and force.

11.1 Path of Ascent of Sap

Soil water (with dissolved substances) $ Root
hairs $ Epidermis $ Cortex (cortical cells)
$ Endodermis $ Pericycle $ Xylem vessels.

12. TRANSPIRATION PULL

It is created due to transpiration of water through
stomata. It is transmitted down to the root hairs.
It pulls the water from a lower level to a higher (a) Isotonic, Endosmosis
level. The transpiration pull plays a very vital role (b) Hypotonic, Active Transport
in the ascent of sap in higher plants. (c) Hypertonic, Endosmosis
(d) Hypertonic, Exosmosis
13. DIFFERENCES BETWEEN DIFFUSION AND OSMOSIS
Ans : SQP 2025
Differences between diffusion and osmosis are as
Thus (d) is correct option.
follows :

Diffusion Osmosis 2. Osmosis takes place when there is:

(a) A freely permeable membrane
1. It is bi-directional. 1. It is unidirectional.
(b) A cell wall
2. No membrane 2. Two solutions (c) A selectively permeable membrane
present. are always (d) An impermeable membrane
separated by a
semi-permeable Ans : MAIN 2024

membrane. Osmosis is the movement of solvent molecules

3. Occurs in liquid 3. Occurs in liquid (usually water) across a selectively permeable
as well as gaseous state only. membrane from an area of lower solute
state. concentration to an area of higher salute
concentration.
4. It is not influenced 4. It is dependent on Thus (c) is correct option.
by solute potential. solute potential.
3. A plant cell may burst when :
(a) Turgor pressure equalises wall pressure.
(b) Turgor pressure exceeds wall pressure.
(c) Wall pressure exceeds turgor pressure.
(d) None of the above.
Ans : MAIN 2016
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 71

A plant cell may burst when turgor pressure 8. State the function of the following :
exceeds wall pressure. (a) Cell wall : Regulates entry of solutes in plant
Thus (b) is correct option. cells.
(b) Regulates entry of solutes in animal cells.
4. Marine fish when placed in tap water bursts (c) Gives rigidity and shape to plant cells.
because of : (d) Gives rigidity and shape to animal cells.
(a) Endosmosis (b) Exosmosis
(c) Diffusion (d) Plasmolysis Ans : SQP 2021

Ans : COMP 2017

Cell wall controls and regulates the direction of cell
growth. Providing the strength, structural support
Marine fish burst when thrown under tap water and maintaining the shape of the cell. Functions
because of endosmosis, because its metabolism is as a storage unit by storing carbohydrates for
different and it is adapted to live in water with a use in plant growth, especially in seeds. It allows
higher concentration of salt in their cells. entry of smaller molecules through it freely.
Thus (a) is correct option. Thus (c) is correct option.
5. The pressure developed in the roots due to 9. Xylem tissue :
continuous inward movement of water by cell to (a) Conducts water and minerals in leaves.
cell osmosis : (b) Does not conduct water and animals in stems.
(a) Root pressure. (c) Conducts food and nutrients to roots.
(b) Wall pressure. (d) Conducts food and nutrients to all parts of
(c) Turgor pressure. the plant.
(d) Air pressure.
Ans : COMP 2021
Ans : SQP 2021
Xylem transports water, minerals, and nutrients
Pressure developed in the roots due to continuous from the soil to all the plant parts. There are
inward movement of water is the root pressure. two types of "transport" tissues in plants- xylem
Thus (a) is correct option. and phloem. Water and solutes are transported
by the xylem from the roots to the leaves, and
6. When a cell is placed in a ______ solution it
food is transported from the leaves to the rest of
becomes plasmolysed.
the plant by the phloem.
(a) Distilled water.
Thus (a) is correct option.
(b) Hypertonic.
(c) Isotonic. 10. Marine fish when placed in tap water bursts
(d) Hypotonic. because of :
Ans : COMP 2021 (a) Endosmosis (b) Exosmosis
(c) Diffusion (d) Plasmolysis
When a cell is placed in the hypertonic solution,
water moves from the cell to its outside. This Ans : MAIN 2017
results in shrinkage of the cytoplasm. This cell Marine fish cannot thrive in the fresh water. The
is called the plasmolysed cell. The cell usually marine fish are accustomed to salt water, which
becomes flaccid. contains a high concentration of solutes (salts),
Thus (b) is correct option. whereas freshwater is devoid of solutes. As a result,
when a marine fish is immersed in freshwater,
7. A shoot from a balsam plant is kept in a beaker
endosmosis causes the freshwater to diffuse into
containing eosin solution (pink). The pink colour
the cells (flow of solutes from an area of lesser
will be distinctly seen in the :
concentration to one of greater concentration).
(a) Xylem (b) Phloem
They will grow and explode as a result of this.
(c) Epidermis (d) Cortex
Thus (a) is correct option.
Ans : MAIN 2021
11. A plant cell may burst when :
The xylem tissues are distinctly visible as they
(a) Turgor pressure equalises wall pressure
have taken the stain indicating that the solution
(b) Turgor pressure exceeds wall pressure
moved through the xylem.
(c) Wall pressure exceeds turgor pressure
Thus (a) is correct option.
(d) None of the above
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CH 3 : ABSORPTION BY ROOTS
Ans : COMP 2016
present dissolved in soil water as a very dilute
The turgor pressure is the amount of pressure that solution. Hence, most of the minerals are actively
allows the cell to maintain its form. Endosmosis absorbed by plant roots in addition to the direct
is the process through which water enters a cell. exchange mechanism.
The turgor pressure rises as a result. The turgor Thus (a) is correct option.
pressure and the wall pressure are always equal.
The cell wall will burst if the turgor pressure 15. Deplasmolysis in a cell occurs when it is placed in:
exceeds the wall pressure. (a) Isotonic solution (b) Hypotonic solution
Thus (a) is correct option. (c) Hypertonic solution (d) None of these
Ans : COMP 2011
12. Girdling of a tree results in the death of the tree
due to: When a plasmolysed cell is placed in a hypotonic
(a) Starvation of root solution, water moves into the cell because of the
(b) Starvation of shoot higher concentration of water outside the cell.
(c) No conduction The cell then swells and become turgid. This is
(d) No upward conduction of food called deplasmolysis.
Thus (b) is correct option.
Ans : SQP 2020

Girdling results in the removal of the phloem and 16. Transport of water in stem takes place through:
death occurs from the inability of the leaves to (a) Phloem (b) Xylem
transport sugars (primarily sucrose) to the roots. (c) Epidermis (d) Endodermis
In this process, the xylem is left untouched and Ans : MAIN 2008
the tree can usually still temporarily transport
Xylem is a specialized tissue in the form of a
water and minerals from the roots to the leaves.
vascular bundle that transports water absorbed
Thus (a) is correct option.
by the roots to the various parts of the plant. It
13. The cell increases in volume if the external also provides physical support.
solution is: Thus (b) is correct option.
(a) Hypertonic
17. Transport of substances against the concentration
(b) Hypotonic
gradient in a cell by using energy is:
(c) Isotonic
(a) Osmosis (b) Diffusion
(d) Concentrated than cell sap
(c) Passive transport (d) Active transport
Ans : MAIN 2010
Ans : SQP 2005
The water molecules move into a cell when a cell
During active transport, substances move against
is placed in a hypotonic medium (resulting in
the concentration gradient, from an area of low
an increase in cell volume) and water moves out
concentration to an area of high concentration.
of the cell when a cell is placed in a hypertonic
This process is “active” because it requires the
medium (resulting in a decrease in cell volume).
use of energy (usually in the form of ATP).
Thus (b) is correct option.
Thus (d) is correct option.

14. Mineral salts are absorbed by roots from the soil 18. Drooping of leaves of Mimosa plant is due to:
in the form of: (a) Change in turgor pressure
(a) Very dilute solution (b) Imbibition
(b) Concentrated solution (c) Plasmolysis
(c) Hypertonic solution (d) Diffusion
(d) Very concentrated solution
Ans : COMP 2000
Ans : SQP 2023
When the Mimosa pudica, commonly known
Minerals are absorbed by plant roots from the as the sensitive plant, is touched by another
soil solution. In the soil, minerals existing as organism, its leaves fold in upon themselves and
positively charged ions are adsorbed on clay its stems droop. The leaves of the Mimosa achieve
particles because clay particles are negatively this rapid folding by a change in turgor pressure.
charged. Some amounts of minerals are also Thus (a) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 73

19. A root hair is: diffusion

(a) Extension of cortical cell Thus (c) is correct option.
(b) Extension of epidermal cell
(c) Specialised multicellular structure 23. How do carbon dioxide and oxygen move into and
(d) Extension of endodermis out of a mesophyll cell?
(a) Active transport (b) Diffusion
Ans : SQP 2007
(c) Respiration (d) Transpiration
Root hairs are the extension of outer epidermal Ans : MAIN 2018
cells of the root. They contain large vacuoles
having cell sap. Because of this property, water is Exchange of gases (CO2 and O2) between the plant
drawn inside the root hair by a process of osmosis. interior and outside air occurs through diffusion.
Thus (b) is correct option. Thus (b) is correct option.

20. Some liquid is collected from the xylem in the 24. What are the important features of osmosis?
stem of a plant. What is present in the liquid? Requires a par- Diffusion Require cell
(a) Cellulose (b) Inorganic ions sally permeable is walls
(c) Starch (d) Sugar membrane involved
Ans : MAIN 2003
(a) { { ×
The main function of xylem is to transport water, (b) × { ×
and some soluble nutrients including minerals and
inorganic ions, upwards from the roots to the rest (c) { × {
of the plant. (d) × × {
Thus (c) is correct option.
Ans : COMP 2017
21. In which order does water pass through the cells Osmosis is a process by which solvent molecules
of a plant, as the water travels from the roots to tend to pass through a semi-permeable membrane
a leaf ? according to the concentration gradient of solvent
(a) Mesophyll cells " root hair " root cortex " molecules across the semi-permeable membrane.
xylem Thus (a) is correct option.
(b) Root cortex " root hair " xylem " mesophyll
cells 25. Which characteristics are correct for both osmosis
(c) Root hair " mesophyll cells " root cortex " and diffusion?
xylem
(d) Root hair " root cortex " xylem " mesophyll Requires a Are energy Require a
cells par-tially consum-ing concentra-
permeable processes lion gradi-
Ans : COMP 2015
membrane ent
When roots absorb water, it moves from root hair (a) { × {
cells to the root cortex cells and then passes on
through xylem to the leaf mesophyll cells from (b) { { ×
where it leaves the plant body and goes to the (c) × × {
atmosphere in form of water vapour during
(d) × { ×
transpiration.
Thus (b) is correct option. Ans : SQP 2014

22. On a dry, sunny day, how does water vapour move Both diffusion and osmosis involve the movement
through the stomata of a leaf? of molecules/particles from higher concentration
(a) Into the leaf by diffusion to lower concentration. Both are passive transport.
(b) Into the leaf by respiration Thus (c) is correct option.
(c) Out of the leaf by diffusion
26. Special anatomical structure through which
(d) Out of the leaf by respiration
guttation occurs are:
Ans : SQP 2021 (a) Hydathode (b) Stomata
Water vapour pass outwardly through stomata by (c) Lenticel (d) Cuticle
CH 3 : ABSORPTION BY ROOTS
Ans : MAIN 2010
Thus (b) is correct option.
Hydathodes are the structures that discharge
water from the interior of the leaf to its surface in 30. Which is an example of active transport?
a process called guttation. (a) Carbon dioxide entering a leaf
Thus (a) is correct option. (b) Oxygen moving from the alveoli into the
blood
27. Osmosis is defined as the diffusion of water (c) Ion uptake by root hair cells
molecules (d) Water uptake by root hair cells
(a) Down their concentration gradient through a Ans : MAIN 2014
permeable membrane.
(b) Up their concentration gradient through a Nutrients such as ions of nitrates, sulphates,
partially permeable membrane. potassium, zinc, manganese, etc., cannot pass
(c) Up their concentration gradient through a through the cell membrane of the root cells easily.
permeable membrane, This is because their concentration is higher
(d) Down their concentration gradient through a inside the root cells. Therefore active transport
partially permeable membrane takes place.
Thus (c) is correct option.
Ans : SQP 2017

During the process of osmosis, the water molecules 31. Match the items in column I with those which
moves down their concentration gradient, i.e., from are most appropriate in column II and choose the
the region of its high concentration to the region correct option.
of its lower concentration through a partially Column I Column II
permeable or semi-permeable membrane.
Thus (d) is correct option. A. Turgid (i) intake of mineral salts
B. Diffusion (ii) a cell charged with
28. Each one of the following contribute to the ascent water
of sap except for:
(a) Wall pressure C. Active (iii) limiting membrane of
(b) Root Pressure transport a vacuole
(c) Capillarity D. Osmosis (iv) movement of particles
(d) Adhesion from higher to lower
Ans : MAIN 2000
concentration

Wall pressure does not contribute to the ascent E. Tonoplast (v) movement of solvent
of sap. across semi-permeable
Thus (a) is correct option. membrane
(a) A-(ii), B-(iv), C-(i), D-(v), E-(iii)
29. Priya observes water droplets on leaves early in (b) A-(iii), B-(iv), C-(i), D-(v), E-(ii)
the morning and learns that this is guttation. (c) A-(i), B-(iv), C-(ii), D-(v), E-(iii)
She needs to identify the conditions under which (d) A-(ii), B-(v), c-(i), D-(iv), E-(iii)
guttation occurs. Plants lose water by guttation
when: Ans : SQP 2017

(a) Rate of transpiration is high A cell charged with water refers to a turgid cell.
(b) Soil is wet and the atmosphere is humid Diffusion is the process of movement of particles
(c) Soil is dry and atmosphere is dry from higher to lower concentration. Active
(d) Soil is wet and atmosphere is dry transport is the intake of mineral salts. Osmosis is
the movement of solvent across a semi-permeable
Ans : MAIN 2001
membrane. Tonoplast is a limiting membrane
The process by which plants loose water in liquid which bounds the chief vacuole of a plant cell.
form is called guttation. This process can usually Thus (a) is correct option.
be witnessed in plants in early morning and at
night, mostly in herbaceous plants growing in 32. Water forms a very important constituent of the
high humidity conditions and high moisture of ............... of the cell.
soil. Guttation water contain many dissolved (a) Nucleus (b) Cytoplasm
minerals. (c) Protoplasm (d) Nucleoplasm
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 75
Ans : COMP 2020 Ans : SQP 2004

Water forms a very important constituent of the Root hairs are the extensions of outer epidermal
protoplasm of the cell. Water constitutes about cells of the root. They contain large vacuoles
65% to 80% of the protoplasm. In protoplasm, which is full of cell sap. The cell sap has a
water is present in both bound as well as free greater concentration of salts as compared to
form. Free form of water provides medium for the surrounding sub-soil water. Because of this
all the biochemical reactions occurring in a cell. property, water is drawn inside the root hair by a
Bound water remains loosely linked with protein process of osmosis.
molecules by hydrogen bonds or other forces. Thus (c) is correct option.
Thus (c) is correct option.
37. ............... takes place when the surrounding
33. Which structures must be present in a cell for solution is more concentrated.
osmosis to take place? (a) Osmosis
(a) Cell (sap) vacuole and cell wall (b) Diffusion
(b) Cell wall and cell membrane (c) Endosmosis
(c) Chloroplast and cytoplasm (d) Exosmosis
(d) Cytoplasm and cell membrane
Ans : MAIN 2017
Ans : SQP 2002
Exosmosis is the outward diffusion of water
In order to function, cells are required to move through a semi-permeable membrane when the
materials in and out of their cytoplasm via their surrounding solution is more concentrated.
cell membranes. Therefore cytoplasm and cell Thus (d) is correct option.
membrane is an important requirement.
Thus (c) is correct option. 38. Cell wall is ...............
(a) Semi-permeable
34. ............... gives cooling effect in plants. (b) Selectively permeable
(a) Transpiration (b) Evaporation (c) Impermeable
(c) Translocation (d) Transportation (d) Freely permeable
Ans : SQP 2002 Ans : SQP 2009

Rapid loss of water in the form of water vapour The cell wall is freely permeable as it allows the
from the aerial parts of the plant through free exchange of water and nutrients between the
transpiration brings down the temperature in cells and outer environment.
plants. Transpiration thus provides a significant Thus (d) is correct option.
cooling effect which keeps the plant from being
over heated. 39. ............... is the relative concentration of solutes
Thus (a) is correct option. dissolved in solution which determine the direction
and extent of diffusion.
35. In the process of ..............., water is used up in (a) Turgidity (b) Tonicity
the green leaves as a raw material in the synthesis (c) Plasmolysis (d) Rigidity
of glucose.
Ans : MAIN 2004
(a) Translocation
(b) Absorption Tonicity is the relative concentration of the
(c) Transpiration solutions that determine the direction and the
(d) Photosynthesis extent of diffusion. Based on tonicity the solutions
are of three types: hypertonic solution, isotonic
Ans : MAIN 2013
solution and hypotonic solution.
The raw materials for the photosynthesis are Thus (b) is correct option.
water, carbon dioxide and sunlight.
Thus (d) is correct option. 40. If a cell is kept in hypotonic solution, ...............
Occurs.
36. Root hairs contain ............... (a) No osmosis (b) Exosmosis
(a) Salt (b) water (c) Endosmosis (d) Osmosis
(c) Cell sap (d) Minerals
Ans : SQP 2021
CH 3 : ABSORPTION BY ROOTS

If a plant cell is kept in a hypotonic solution then 45. ............... Reverse of plasmolysis occurs when the
the plant cell gains water or endosmosis occurs cell is kept in.
and becomes turgid. (a) Pond water (b) 10% sugar solution
Thus (c) is correct option. (c) 5% salt solution (d) Pure water

41. ............... is the pressure exerted by all contents Ans : MAIN 2016

on the cell wall. Plasmolysis can be reversed if the cell is placed in

(a) Osmotic pressure (b) Turgor pressure a hypotonic solution. When a plasmolysed cell is
(c) Wall pressure (d) All of the above placed in a hypotonic solution such as pure water,
Ans : MAIN 2016
(i.e., the solution having solute concentration
lower than the cell sap), the water moves into the
Turgor pressure is the force within the cell that cell because of the higher concentration of water
pushes the plasma membrane against the cell outside the cell than in the cell. The cell then
wall. It is also called hydrostatic pressure. Turgor swells to become turgid. It is called deplasmolysis.
is what makes living plant tissue rigid. Thus (d) is correct option.
Thus (b) is correct option.
46. No net flow occurs when a cell is kept in ...............
42. ............... occurs through semi-permeable (a) Hypotonic solution (b) Hypertonic solution
membrane. (c) 5% sugar solution (d) Isotonic solution
(a) Osmosis (b) Diffusion
(c) Imbibition (d) Transportation Ans : SQP 2020

Ans : COMP 2006

If a cell is placed in an isotonic solution, there will
be no net flow of water into or out of the cell and
Osmosis is a process by which solvent molecules the cell’s volume will remain stable.
tend to pass through a semi-permeable membrane Thus (d) is correct option.
according to the concentration gradient of solvent
molecules across the semi-permeable membrane. 47. Loss of water (cell sap) through a cut stem is
Thus (a) is correct option. called ...............
(a) Bleeding (b) Guttation
43. Flaccidity is the reverse of ............... (c) Transpiration (d) Injury
(a) Turgidity (b) Plasmolysis
(c) Deplasmolysis (d) Both a and c Ans : COMP 2000

Ans : MAIN 2010

The exudation of water and cell sap through the
cuts or wound of plants is called as bleeding.
Flaccidity is the reverse of turgidity, the cell Thus (a) is correct option.
content is shrunken and the cell is no tighter. In
deplasmolysis also the cell achieves turgid state. 48. Cell slightly enlarges or bursts when kept in.
Thus (d) is correct option. (a) Hypertonic solution (b) Hypotonic solution
(c) Isotonic solution (d) Pond water
44. ............... is the result of inward movement of
water molecules. Ans : SQP 2011

(a) Plasmolysis A hypotonic solution means a solution having a

(b) Flaccidity lower osmotic pressure as compared to another
(c) Deplasmolysis solution. So if a plant cell is kept in a hypotonic
(d) Both b and c solution, then water will flow from the solution
Ans : SQP 2003
into the plant cell through the cell membrane and
cell will swell up due to the uptake of water.
Plasmolysis is the process in which the cells Thus (b) is correct option.
lose water in a hypertonic solution. The reverse
process of plasmolysis is deplasmolysis, which 49. Salting of meat of addition of salt to pickles is a
occurs when the cell is in a hypotonic solution method of preservation by ............... .
and results in a lower external osmotic pressure (a) Osmosis (b) Exosmosis
and a net flow of water into the cell. (c) Plasmolysis (d) Deplasmolysis
Thus (c) is correct option.
Ans : COMP 2015
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 77

All living walled cells plasmolyse when kept in 53. ............... is a phenomenon by which the living
a hypertonic solution. Pickels, meat and fish are or dead plant cells absorb water by surface
preserved by salting. Salting create hypertonic attraction.
condition in which the fungi and bacteria get (a) Imbibition (b) Diffusion
killed by plasmolysis. (c) Absorption (d) Transportation
Thus (c) is correct option.
Ans : MAIN 2015

50. Which one of the following is not the example of Imbibition is a phenomenon by which the dry
semi-permeable membrane? surface of the living or dead plant cells absorb
(a) Cellophane paper (b) Egg membrane water by surface attraction. During the process
(c) Animal bladder (d) Rubber sheet of imbibition, water is absorbed by the solid
Ans : SQP 2003
particles called colloids, causing an enormous
increase in volume.
Cell membrane or plasma membranes of plant cells Thus (a) is correct option.
and animal cells, egg’s membrane, Goat’s bladder
membrane are the natural substances which act 54. ............... pressure causes rupturing of seed coat
as semi-permeable membrane. Cellophane paper, in case of germination.
Parchment paper, Visking bag are the substances (a) Wall (b) Osmotic
which act as semi-permeable membrane and (c) Root (d) Imbibition
are artificial in nature. Rubber sheet is an
Ans : COMP 2013
impermeable membrane.
Thus (d) is correct option. During the beginning stage of the germination,
the seeds take up water rapidly and this results
51. The concentration gradient of the ions in active in swelling and softening of the seed coat at an
transport is opposite to that of ............... optimum temperature. The process of absorption
(a) Osmosis of water is called imbibition. This absorption of
(b) Diffusion water creates a massive imbibitional pressure
(c) Imbibition which causes rupturing of seed coat which helps
(d) All of the above radicle and plumule to come in contact with the
Ans : COMP 2007
outer environment and they start growing into a
new plant.
During active transport, molecules move from Thus (d) is correct option.
an area of low concentration to an area of high
concentration. This is the opposite of diffusion 55. The leaves get wilted and droop down if ...............
and these molecules are said to flow against their (a) Phloem is removed
concentration gradient. Active transport is called (b) Cambium is removed
‘active’ because this type of transport requires (c) Xylem is removed
energy to move molecules. (d) Both a and b
Thus (b) is correct option.
Ans : SQP 2008

52. ............... of a solution is a measure of its tendency Xylem transports water and minerals in plants
to take in water by osmosis. from roots up to the stem, to the leaves. If Xylem
(a) Turgor pressure is removed from a plant, the plant will not be able
(b) Wall pressure to transport water to leaves which will hinder,
(c) Osmotic pressure hindering various processes like photosynthesis,
(d) Root pressure transpiration, growth etc. The plant will initially
Ans : SQP 2000
wilt and then ultimately die.
Thus (c) is correct option.
Osmotic pressure is the minimum pressure which
needs to be applied to a solution to prevent the 56. Turgor pressure helps in the opening and closing
inward flow of its pure solvent across a semi- of ...............
permeable membrane. It is also defined as the (a) Lenticels (b) Cuticle
measure of the tendency of a solution to take in a (c) Stomata (d) All of the above
pure solvent by osmosis.
Ans : MAIN 2010
Thus (c) is correct option.
CH 3 : ABSORPTION BY ROOTS

The turgor pressure, which is caused by the 60. The removal of water in the form of water droplets
osmotic flow of water in the guard cells, controls along the margins of the leaf is called ...............
the opening and closing of stomata. When the (a) Bleeding
guard cells become turgid, they expand, causing (b) Guttation
stomata to open. Guard cells become flaccid as (c) Transpiration
they lose water, causing stomatal closure. (d) Evaporation
Thus (c) is correct option.
Ans : SQP 2001

57. Root pressure is built up due to cell-to-cell The loss or excretion of water in the form of
............... liquid droplets from the leaves and other parts
(a) Imbibition (b) Osmosis of uninjured or intact plant is called guttation.
(c) Diffusion (d) Absorption Guttation takes place through special structures
Ans : COMP 2001
called hydathodes. They are usually found on the
margins and tips of the leaves.
Root pressure is the transverse osmotic pressure Thus (b) is correct option.
within the cells of a root system that causes sap
to rise through a plant stem to the leaves. Water 61. Guttation mainly occurs during ...............
then diffuses from the soil into the root xylem (a) Hot weather
due to osmosis. Root pressure is caused by this (b) Dry weather
accumulation of water in the xylem pushing on (c) Windy day
the rigid cells. (d) Warm humid weather
Thus (b) is correct option.
Ans : MAIN 2007

58. Drops of water along the leaf margin are due to Guttation usually occurs during dry weather
excessive ............... when transpiration rate is very low as compared
(a) Transpiration (b) Root Pressure to rate of water absorption.Due to this root
(c) Osmotic Pressure (d) Wall Pressure pressure is developed and water is pushed out
Ans : SQP 2019
through specialized pores at vein endings called
hydathodes. Each hydathode is made up of group
In the morning, drops of water appear on margins of loosely arranged achlorophyllous or colourless
of leaves due to root pressure and this process is and parenchymatous cells called epithem. These
called as guttation. High root pressure forces the cells help in absorbing a good percentage of
water all the way through stem and it comes out inorganic and organic solutes present in the
through the end of leaf veins. Thus, guttaion can exudate. Thus, guttation is due to the positive
be defined as the process by which drops of water pressure in the xylem developed due to the root
appear along leaf margins due to excessive root pressure.
pressure. Thus (b) is correct option.
Thus (b) is correct option.
62. The state of a cell in which the cell wall is rigid
59. Movement of molecules of a substance from and stretched by the increase in volume due to
their region of higher concentration to lower the absorption of water is called:
concentration when they are in direct contact.
(a) Flaccidity
(a) Diffusion (b) Endosmosis
(c) Imbibition (d) Active transport (b) Turgidity

Ans : COMP 2015 (c) Capillarity

Diffusion is the movement of molecules of a (d) Tonicity

substance from their region of higher concentration Ans : COMP 2015
to lower concentration when they are in direct
contact. This movement occurs as a result of the The state of a cell in which the cell wall is rigid
random and constant motion characteristic of all and stretched by the increase in volume due
molecules, atoms, or ions (due to kinetic energy) to the absorption of water is called turgidity.
and is independent from the motion of other Turgidity is essential in plant cells to make them
molecules. keep standing upright.
Thus (a) is correct option. Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 79

63. Osmosis and Diffusion are the same except that which is supplied by the cell in the form of ATP.
in Osmosis there is: Thus (d) is correct option.
(a) A free permeable membrane.
(b) A cell wall in between. 66. Active transport
(c) A selective permeable membrane in between. (a) Passage of water from its lower to higher
(d) An endless inflow of water into a cell concentration through a cell membrane
without any expenditure of energy.
Ans : SQP 2001
(b) Passage of ions from its lower to higher
Diffusion is the free movement of molecules of a concentration through a cell membrane
substance from their region of higher concentration without any expenditure of energy.
to their region of lower concentration when the (c) Passage of water from its lower to higher
two are in a direct contact but in case of osmosis concentration through a cell membrane using
the same movement occurs but the two are energy from the cell.
separated by a selectively permeable membrane (d) Passage of ions from its lower to higher
called as the semi-permeable membrane. concentration through a cell membrane using
Thus (c) is correct option. energy from the cell.

64. The space between the cell wall and plasma Ans : MAIN 2002

membrane in a plasmolysed cell is filled with: Active transport is the passage of ions from its
(a) Isotonic solution (b) Hypotonic solution lower to higher concentration through a cell
(c) Hypertonic solution (d) Water membrane using energy which is supplied by the
cell in the form of ATP.
Ans : MAIN 2006
Thus (d) is correct option.
The space between the cell wall and plasma
membrane in a plasmolysed cell is filled with 67. Guttation
hypertonic solution. This is because the cell wall of (a) The loss of water in the form of water droplets
plant is fully permeable and it cannot control the from the surface of the leaf.
entry or exit of molecules of a substance. When (b) The loss of water in the form of water droplets
this plant cell is placed in a hypertonic solution, through the stomata.
it will lose water by exosmosis due to which the (c) The loss of water in the form of water droplets
protoplasm of plant cell will shrink and will move along the leaf margin.
inwards and away from the cell wall. This process (d) The loss of water in the form of water vapour
is called as plasmolysis. As a result of plasmolysis, along the leaf margin.
the hypertonic solution will occupy the space Ans : SQP 2008
between the cell wall and plasma membrane in a
plasmolysed cell. Guttation is the loss of water in the form of water
Thus (c) is correct option. droplets from hydathodes (small pores present on
the leaf margin) along the leaf margin of a small
65. Which of the following takes place in active herbaceous plant. This process occurs especially
transport? in the early mornings.
(a) Movement of a substance form its higher to Thus (c) is correct option.
lower concentration
(b) Movement of water from its lower to higher 68. Ascent of sap
concentration (a) Upward movement of ions from the root hair
(c) Movement of water from its higher to lower to aerial parts of the plant body.
concentration (b) Upward movement of water along with the
(d) Movement of a substance from its lower to minerals from the root to aerial parts of the
higher concentration plant body.
(c) Upward movement of solution from the root
Ans : SQP 2018
to aerial parts of the plant body by the
Active transport is the movement of a substance process of diffusion.
(salt or ion) from its higher concentration to lower (d) Upward movement of solute from the root to
concentration through a living cell membrane aerial parts of the plant body by the process of
against a gradient with the use of external energy osmosis through semi-permeable membrane.
CH 3 : ABSORPTION BY ROOTS
Ans : MAIN 2012
Tonicity is the relative concentration of the
The upward movement of water and dissolved solutions that determine the direction and the
mineral salts from roots upwards to the leaves extent of diffusion. Based on tonicity the three
and other aerial parts is called Ascent of Sap. It types of solutions are: isotonic, hypotonic and
is called the sap as it contains many dissolved hypertonic solution.
minerals. The root pressure and transpiration Thus (c) is correct option.
pull helps in the conduction of water upwards
to the leaves and other aerial parts of the plant 71. Hydathode
through xylem. (a) Helps in transpiration
Thus (b) is correct option. (b) Helps in guttation
(c) Helps in imbibition
69. Osmosis (d) Helps in transportation of water
(a) Movement of water molecules from their lower Ans : MAIN 2022
concentration to their higher concentration
through a semi permeable membrane. Hydathodes are small pores found in the epidermis
(b) Movement of solutes from their lower of the leaves of certain plants. They are used
concentration to their higher concentration by the plant to secrete water under conditions
through a semi permeable membrane. in which transpiration is inhibited, for example,
(c) Movement of water molecules their higher when the atmosphere is very humid, the water is
concentration to their lower concentration lost from the margins of the leaf in the form of
through a semi-permeable membrane. water droplets. This process of water loss is called
(d) Movement of water molecules from their higher guttation.
concentration to their lower concentration Thus (b) is correct option.
through a freely permeable membrane.
72. Phloem
Ans : SQP 2020 (a) Helps in transportation of food
In osmosis, the movement of water through a (b) Helps in transportation of water
semipermeable membrane occur according to
(c) Helps in transportation of mineral
the concentration gradient of water across the
membrane, which is inversely proportional to (d) Helps in transportation of air
the concentration of solutes which means that in Ans : SQP 2023
osmosis, the movement of water molecules takes
place from their higher concentration (dilute Phloem tissues in plants is composed of various
solution or with a lower solute concentration) to specialized cells such as sieve tubes, companion
their lower concentration (concentrated solution cells, phloem fibres, and phloem parenchyma
or with a higher solute concentration) through a cells. Its main function is the conduction of food
semi-permeable membrane. made in the leaves to all other parts of the plant.
Thus (c) is correct option. Thus (a) is correct option.

70. Tonicity 73. Semi-permeable membrane

(a) Relative concentration of the solute that (a) Allows free movement of only ions through it.
determine the direction and the extent of (b) Allows free movement of molecules or ions
osmosis through it
(b) Relative concentration of the solute and
(c) Allows certain molecules or ions to pass
solvent that determine the direction and the
through it.
extent of diffusion.
(c) Relative concentration of the solutions that (d) Allows movement of water through it.
determine the direction and the extent of
Ans : COMP 2004
diffusion.
(d) Relative concentration of the solute and Semi-permeable membrane is a selectively
solvent that determine the direction and the permeable cell membrane that allows the
extent of osmosis. movement of certain molecules or ions through it
by means of active or passive transport.
Ans : SQP 2019
Thus (c) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 81

74. Root hairs Xylem is located in the centre of the vascular

(a) Absorption of ions and minerals from the soil. bundle, deep in the plant. Their movement
(b) Absorption of water and minerals from the is unidirectional and it transports water and
soil. minerals from roots to other aerial parts of the
(c) Absorption of oxygen and minerals from the plant.
soil. Thus (c) is correct option.
(d) Absorption of gases and minerals from the
soil. 78. The diagram shows a cross-section through a
plant stem.
Ans : MAIN 2008

Root hairs are the extension of outer epidermal

cells of the root. They help in the absorption of
water and minerals from the soil. Apart from
that, they provide anchoring to the plant and
store food.
Thus (b) is correct option.

75. Xylem
(a) Translocation of food from the leaves to the
other parts of the plant.
(b) Conduction of food. X shows the part that is stained red when the
(c) Conduction of water and food. stem is placed in water containing a red dye.
(d) Conduction of water and minerals from the What is found at X?
root to the other parts of the plant. (a) Guard cells (b) Palisade cells
(c) Xylem (d) Phloem
Ans : SQP 2019
Ans : SQP 2016
Xylem is a specialised tissue of vascular plant
and its main function is Conduction of water and The vascular bundles are arranged near the edge
minerals from the root to the other parts of the of the stem, with the phloem on the outside and
plant. the xylem on the inside.
Thus (d) is correct option. Thus (c) is correct option.

76. Root hair 79. The diagram shows the structure of a plant cell.
(a) Extension of the cortex What is a function of this specialised plant cell?
(b) Extension of epithelium
(c) Extension of epidermis
(d) Extension of endodermis
Ans : MAIN 2010

Root hairs are the extensions of the outer

epidermal cells of the root. They contain large (a) It absorbs carbon dioxide from the air.
vacuole which is filled with cell sap. This cell (b) It absorbs ions from the soil.
sap has some salts dissolved in it and therefore (c) It transports sucrose from leaves.
it has greater concentration as compared to the (d) It transports water in stems.
surrounding sub-soil water.
Thus (c) is correct option. Ans : MAIN 2010

Plants absorb water from the soil by osmosis.

77. Xylem They absorb mineral ions by active transport,
(a) Centre of the vascular bundle. against the concentration gradient. Root hair cells
(b) Outer side of the vascular bundle. are adapted for taking up water and mineral ions
by having a large surface area to increase the rate
(c) On the margins of leaves
of absorption.
(d) On the margins of roots. Thus (b) is correct option.
Ans : COMP 2007
CH 3 : ABSORPTION BY ROOTS

80. The diagram shows two solutions that are Ans : MAIN 2005

separated by a partially permeable membrane. The above plant cell shows a plasmolysed state
which occurs when it is kept in a hypertonic
solution or a solution whose water potential is less
than that of the cell sap. Due to exosmosis there
is shrinkage of protoplast or the cell becomes
flaccid.
Thus (c) is correct option.

82. The diagram represents two liquids, separated by

a membrane through which osmosis can occur.

In which direction will most water molecules

move in relation to their concentration gradient?
(a) From X to Y against their concentration
gradient.
(b) From Y to X against their concentration
What movement of molecules will occur?
gradient.
(a) Molecules of dissolved substance move from
(c) From Y to X down their concentration
left to right.
gradient.
(b) Molecules of dissolved substance move from
(d) From X to Y down their concentration
right to left.
gradient.
(c) Overall, water molecules move from left to
Ans : MAIN 2013 right.
Since more free water molecules are present on (d) Overall, water molecules move from right to
the side of dilute solution X, more of them will left.
pass to enter the solution Y. Ans : COMP 2019
Thus (d) is correct option.
Osmosis is a process of movement of solvents
81. The diagram shows a plant cell after it has been through a semipermeable membrane from a
submerged in a solution, for 15 minutes. region of lower solute concentration to higher
solute concentration. In this case, water will move
from left to right.
Thus (c) is correct option.

83. The diagram shows a specialized cell.

Which option describes the tonicity of solution P

and the condition of the cell?
(a) Solution P is hypertonic than the cell sap and
the cell is plasmolysed and turgid.
(b) Solution P is hypotonic than the cell sap and
For which function is the cell adapted?
the cell is plasmolysed and turgid.
(a) Absorption of water
(c) Solution P is hypertonic than the cell sap and
(b) Contraction of muscles
the cell is plasmolysed and flaccid.
(c) Movement of dust particles
(d) Solution P is hypotonic than the cell sap and
(d) Transport of oxygen
the cell is plasmolysed and flaccid.
Ans : MAIN 2016
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 83

The function of the root hair cell is to obtain (a) If both assertion and reason are true and
water from the ground and transport this to the reason is the correct explanation of assertion.
Xylem. Plants absorb water from the soil by (b) If both assertion and reason are true, but
osmosis. Root hair cells are adapted for this by reason is not the correct explanation of
having a large surface area to speed up osmosis. assertion.
This speeds up the movement of water by osmosis. (c) If assertion is true but reason is false.
Thus (a) is correct option. (d) If both assertion and reason are false.

84. Phloem Ans : SQP 2003

(a) Between the lower and upper epidermis. Most minerals enter the root by active absorption
(b) Outer side of the vascular bundle. into the cytoplasm of epidermal cells. This
(c) On the lower epidermis of leaves transportation needs energy in the form of ATP,
(d) Deep in the plant some ions also move into the epidermal cells
Ans : MAIN 2014
passively.
Thus (a) is correct option.
Phloem is located on the outer side of the vascular
bundle. Their movement is bidirectional and it 87. Assertion : Mineral nutrients are an essential
helps in the transport of food from roots to other constituent of the cell and help to synthesis many
aerial parts of the plant. compounds or enzymes in the cell.
Thus (b) is correct option. Reason : The absorption of minerals from the soil
is done by the roots only.
(a) If both assertion and reason are true and
reason is the correct explanation of assertion.
ASSERTION AND REASON (b) If both assertion and reason are true, but
reason is not the correct explanation of
assertion.
85. Assertion : A special type of diffusion of water (c) If assertion is true but reason is false.
through a semi-permeable membrane is known as (d) If both assertion and reason are false.
osmosis.
Ans : MAIN 2007
Reason : The net direction of osmosis depends on
the pressure gradient. Mineral nutrients are an essential constituent of
(a) If both assertion and reason are true and the cell. The mineral concentration within the soil
reason is the correct explanation of assertion. is very low, therefore, it is dissolved in water and
(b) If both assertion and reason are true, but move around the soil in solution. Plants absorb
reason is not the correct explanation of the minerals from the soil with the help of root
assertion. hairs.
(c) If assertion is true but reason is false. Thus (b) is correct option.
(d) If both assertion and reason are false.
88. Assertion : In hypertonic solution, a plant cell
Ans : SQP 2007 shrinks.
Osmosis is diffusion of water from its pure state Reason : Due to plasmolysis in hypertonic
(or dilute solution) into a solution (or stronger solution, water moves out of the cells.
solution) when the two are separated by a semi- (a) If both assertion and reason are true and
permeable membrane. The difference in the reason is the correct explanation of assertion.
water potentials of solutions separated by a semi- (b) If both assertion and reason are true, but
permeable membrane determine the net direction. reason is not the correct explanation of
Thus (c) is correct option. assertion.
(c) If assertion is true but reason is false.
86. Assertion (A) : Most minerals must enter the (d) If both assertion and reason are false.
root by active absorption into the cytoplasm of
Ans : MAIN 2017
epidermal cells.
Reason (R) : This transportation needs energy in In a hypertonic solution, when the cell is placed
the form of ATP. Some ions also move into the water moves out; it is first lost from the cytoplasm
epidermal cells passively. and then from the vacuole. When water is drawn
CH 3 : ABSORPTION BY ROOTS

out of the cell into the extracellular (outside cell) (c) If assertion is true but reason is false.
fluid, it causes the protoplast to shrink away from (d) If both assertion and reason are false.
the walls. The cell is said to be plasmolysed.
Ans : COMP 2014
Thus (a) is correct option.
Plants have the potential to absorb water through
89. Assertion : In the turgid state, the cell is balanced their entire surface right from root, stem, leaves,
i.e. no water enters or leaves it. flowers, etc. However, as water is available mostly
Reason : The turgor pressure and the wall in the soil, only the underground root system is
pressure balance each other and no absorption of specialized to absorb water. In roots, the most
water occurs. efficient region of water absorption is the root hair
(a) If both assertion and reason are true and zone. The root cap has the functions of protecting
reason is the correct explanation of assertion. the delicate stem cells within the root tip.
(b) If both assertion and reason are true, but Thus (c) is correct option.
reason is not the correct explanation of
assertion.
(c) If assertion is true but reason is false.
(d) If both assertion and reason are false.
ONE MARK QUESTIONS
Ans : COMP 2020

Turgor pressure (TP) is the pressure exerted by DIRECTION : Name the following :
protoplasm on the wall and wall pressure (WP)
is the pressure exerted by the wall on to the 1. Expand the abbreviation-NADP.
protoplasm. If TP is equal to WP it means that
there is no net movement of water into the cell Ans : MAIN 2024

and cell is fully turgid. NADP stands for Nicotinamide Adenine

Thus (a) is correct option. Dinucleotide Phosphate.

90. Assertion : Imbibition involves the absorption 2. Unicellular outgrowths from the epidermis of
of water molecules by living or dead plant cells mots.
through their hydrophilic surfaces.
Ans : MAIN 2024
Reason : When seeds germinate, the seed coat
breaks due to the imbibition pressure. Root hairs
(a) If both assertion and reason are true and
3. The tissue that transports manufactured starch
reason is the correct explanation of assertion.
from the leaves to all parts of plants.
(b) If both assertion and reason are true, but
reason is not the correct explanation of Ans : MAIN 2004
assertion. Phloem
(c) If assertion is true but reason is false.
(d) If both assertion and reason are false. 4. The tissue responsible for the ascent of sap in
Ans : SQP 2009
plants.

Imbibition is the absorption of water by living, Ans : SQP 2003

or dead plant cells by surface attraction e.g., Xylem

absorption of water by seeds.
Thus (b) is correct option. 5. The pressure responsible for the movement of
water molecules across the cortical cells of the
91. Assertion : Plants absorb water mostly by roots. root.
Reason : Root cap region participates actively in
Ans : COMP 2003
water absorption.
(a) If both assertion and reason are true and Turgor/root pressure
reason is the correct explanation of assertion.
6. Condition of a cell placed in hypotonic solution.
(b) If both assertion and reason are true, but
reason is not the correct explanation of Ans : MAIN 2002
assertion. Turgid
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 85

7. The process by which water enters the root hair Imbibition

cell.
17. The instrument used to measure root pressure.
Ans : COMP 2001
Ans : MAIN 2020
Osmosis
Manometer
8. The pressure exerted by cell contents on a plant
cell wall. 18. One factor that affect water potential in plant.

Ans : SQP 2000 Ans : COMP 2023

Turgor pressure Number of moles of the substance present at

atmospheric pressure.
9. Tissue concerned with upward conduction of
water in plants. 19. Name the terms used in reference to concentration
between two solutions.
Ans : MAIN 2000, 1997
Ans : SQP 2021
Xylem
Tonocity
10. Condition of cell in which the cell contents are
shrunken. 20. Shrinkage of protoplasm when a cell is kept in a
hypertonic solution.
Ans : SQP 2009, 1997
Ans : MAIN 2016
Plasmolysed/flaccid
Plasmolysis
11. The inward movement of solvent molecules
through the plasma membrane of a cell. 21. The process in which water absorption needs
metabolic energy.
Ans : COMP 2005, 1997
Ans : COMP 2015
Endosmosis
Active absorption
12. The process by which raisins swell up when placed
in a beaker of water. 22. The tissue which conducts water and minerals
from the root to the other parts of the plant.
Ans : MAIN 2010, 1996
Ans : COMP 2021
Endosmosis
Xylem
13. Movement of molecules from a region of high
concentration to a region of low concentration. 23. Movement of water out of a cell when it is kept in
a hypertonic solution.
Ans : SQP 2009
Ans : SQP 2001
Diffusion
Exosmosis
14. The process by which root hairs absorb water
from the soil. 24. A cell in a fully extended condition.

Ans : COMP 2017 Ans : MAIN 2008

Osmosis Turgid

15. The process of uptake of mineral against the 25. The process which does not require the expenditure
concentration gradient using energy cell. of metabolic energy for the upward movement of
water.
Ans : MAIN 2015
Ans : SQP 2017
Active transport
Passive absorption
16. The phenomenon by which living or dead plant
cells absorb water by surface attraction. 26. What is suction pressure ?

Ans : SQP 2012 Ans : SQP 2003

CH 3 : ABSORPTION BY ROOTS

The net force with which the water is drawn into 36. The condition of the cell when it is placed in a
a cell is called suction pressure. hypotonic solution.

27. The disc like structures of chloroplast in which Ans : MAIN 2021

chlorophyll is present. Deplasmolysis

Ans : MAIN 2001
37. The kind of cells that constitute the cortex of a
Thylakoid. root.

28. Movement of solvent molecule from its higher Ans : MAIN 2012

concentration to its lower concentration through Parenchyma

a semipermeable membrane.
38. The condition of a cell when it is kept in a
Ans : SQP 2010
hypotonic solution.
Osmosis
Ans : COMP 2000

29. Pressure of the cell contents on the cell wall. Turgidity

Ans : MAIN 2004
39. The term for the inward movement of solvent
Turgor pressure molecules through the plasma membrane of a cell.
Ans : MAIN 2009
30. The tissue which conducts manufactured food in
Endosmosis
plants.
Ans : MAIN 2015 40. The force which helps in the conduction of water.
Phloem Ans : COMP 2004

Cohesive force/Transpiration pull.

31. A solution whose concentration is greater than
the cell sap. 41. The pressure, which is responsible for upward
Ans : COMP 2023 movement of water across the cortical cells of the
root.
Hypertonic solution
Ans : SQP 2017
32. A solution whose concentration is equal to the
Root pressure
cell sap.
Ans : MAIN 2020 42. The organ that transports water from the soil to
another parts of the plant.
Isotonic solution
Ans : COMP 2019
33. Two factors that affect water potential.
Root hairs
Ans : COMP 2014
43. The process by which molecules distribute
Atmospheric pressure ; Number of moles of the
themselves evenly within the space they occupy.
substance present
Ans : MAIN 2010
34. A solution whose concentration is less than cell
Diffusion
sap.
Ans : COMP 2018 44. The upward movement of water and minerals
from roots to leaves and other parts of plants.
Hypotonic solution
Ans : SQP 2017

35. The movement of molecules of substance from its Ascent of sap

higher concentration to its lower concentration.
45. A solution whose concentration is greater than
Ans : SQP 2014 that of cell sap.
Diffusion Ans : MAIN 2002
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 87

Hypertonic solution 55. The process of mixing of two different substances/

molecules.
46. The unique property of water which make it
possible to rise in tall plants. Ans : MAIN 2010

Ans : MAIN 2004

Diffusion.

Cohesion and adhesion

DIRECTION : Complete the following :
47. The term which refers to relative concentrations
of solutes of two solutions. 56. Wooden doors swell up in rainy season due
Ans : SQP 2001
to______.

Tonicity Ans : COMP 2011

Imbibition
48. Exudation of watery sap from an injured part of
the plants. 57. ______tissue translocate food in plants.
Ans : MAIN 2006 Ans : MAIN 2011

Bleeding Phloem

49. A semi-permeable membrane in plants. 58. The pressure that helps the water to move up in
Ans : a plant is ______.

Cell membrane Ans : SQP 2008

Root pressure
50. A solution in which cell swells up.
Ans : 59. In a hypotonic solution, cell becomes______.

Hypotonic Ans : COMP 2017

Turgid
51. The condition in which cell shrinks.
Ans : SQP 2023
60. Root pressure can be measured by ______.

Flaccid Ans : SQP 2009

Manometer
DIRECTION : Give the biological / technical term 61. Water potential of a cell is lowered by the addition
for the following : of______.

52. The process of uptake of mineral ions against the Ans : COMP 2021

concentration gradient using energy from the cell. Solutes

Ans : COMP 2016
62. The concentration of the cell sap ______as
Active transport plasmolysis takes place.

53. Movement of molecules of a substance from their Ans : MAIN 2004

higher concentration to lower concentration when Increases

they are in direct contact.
63. When plants absorb water from the soil, the water
Ans : MAIN 2018
potential of root cell is ______than the soil.
Diffusion
Ans : SQP 2010

54. A membrane which allows the passage of molecules low

selectively.
64. The solution which has the same concentration
Ans : SQP 2012
of dissolved particles as inside the cell is called
Semi-permeable membrane ______
CH 3 : ABSORPTION BY ROOTS
Ans : MAIN 2023
Semipermeable
Isotonic
75. ______ is an example of a semipermeable
65. The condition opposite to turgid is______. membrane.
Ans : COMP 2021 Ans : MAIN 2014

Flaccid Egg membrane/Goat’s bladder

66. Root hair is an extension of______. 76. Leaves get wilted if______is removed from the
plant.
Ans : COMP 2018
Ans : COMP 2020
Epidermal cell
Xylem
67. ______does not require an energy input to
operate. 77. The pressure which develops in the cortical cells
of root exerts force to push water upward is
Ans : SQP 2020
called______.
Passive transport
Ans : SQP 2015

68. The first process by which water enters into Root pressure
the seed coat when a seed is placed in suitable
situation for germination is ______. 78. The root hair is an extention of______.
Ans : MAIN 2010 Ans : MAIN 2022

Imbibition Epiblema/epidermis of root cells

69. The loss of turgor of guard cells result in 79. Absorption of water in plants takes place through
______of stomata. the roots by the process of______.
Ans : COMP 2016 Ans : SQP 2003

Closing Osmosis

70. A plasmolysed cell has ______ protoplast. 80. ______helps in the opening of stomata.
Ans : SQP 2014 Ans : COMP 2014

Shrunken Turgidity

71. A solution which has lower concentration of solute 81. The condition of a cell when it is placed in a
molecules, has a ______ osmotic pressure. hypertonic solution is called______.
Ans : MAIN 2011 Ans : MAIN 2008

Greater Flaccidity

72. Metabolic energy of the cell is utilized in______ 82. ______is the medium through which transport
absorption of water . of minerals takes place in plants.
Ans : COMP 2009 Ans : SQP 2016

Active Water

73. Raisin swells up when kept in a ______ 83. The spreading of molecules evenly within the
solution. space they occupy is______.
Ans : MAIN 2001 Ans : MAIN 2009

Hypotonic Diffusion

74. The cell membrane is______. 84. Recovery of protoplasm when a cell is kept in a
hypotonic solution is______.
Ans : COMP 2000
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 89
Ans : COMP 2014
94. The following paragraph is related to absorption
Deplasmolysis of water from the soil. Copy and complete the
following paragraph by selecting the correct word
85. The root hair is ______ and thin walled. from those given in the box. You may use the
Ans : SQP 2007 term only once.
Unicellular

86. The diffusion of a ______ across the

semipermeable membrane is known as osmosis.
Water enters the root hair from the soil by the
Ans : MAIN 2010 process of______. This is because the solution
Solvent in the soil is______whereas the cell sap in
the root hair cell is______. The water then
87. The solution inside the vacuole is______. passes through the______cells (cell to cell)
by______and reaches the xylem of the root.
Ans : COMP 2020

Cell sap Ans : SQP 2004

88. The cell wall of a root hair is ______ permeable. Water enters the root hair from the soil by the
process of endosmosis. This is because the solution
Ans : SQP 2022
in the soil is hypotonic whereas the cell sap in the
Freely root hair cell is hypertonic. The water then passes
through the cortical cells (cell to cell) by osmosis
89. Plants absorb water through______. and reaches the xylem of the root.
Ans : MAIN 2023

Root hairs DIRECTION : State true or false;

90. Osmosis is the movement of water molecules from 95. Cells that have lost their water content are said to
its region of high concentration to a region of lower be deplasmolysed.
concentration through a ______ membrane. Ans : SQP 2004, 1999

Ans : SQP 2014 False

Semi-permeable
96. Xylem is the water conducting tissue in plants.
91. Wooden doors swell up in rainy season due Ans : MAIN 2005, 1999
to______.
True
Ans : MAIN 2009

Wooden doors swell up in rainy season due to 97. Spreading of particles by mixing is called diffusion.
Imbibition.
Ans : SQP 2007, 1999

92. ______ is the phenomenon of contraction of True

the cytoplasm from the cell wall.
98. Root hairs are extension of epidermal cells.
Ans : COMP 2011
Ans : COMP 2009, 1995
Plasmolysis is the phenomenon of contraction of
the cytoplasm from the cell wall. True

93. The phenomenon of loss of water through a cut 99. Free movement of solutes in and out of the cell
stem or injured part of plant is called______. takes place across the cell membrane.
Ans : SQP 2015 Ans : SQP 2017

The phenomenon of loss of water through a cut False. Free movement of solutes in and out of the
stem or injured part of plant is called bleeding cell takes place across the cell wall.
CH 3 : ABSORPTION BY ROOTS

100. Raisins swell up when placed in a medium which 108. The space between the cell wall and plasma
is hypertonic solution. membrane in plasmolysed cell is filled with
(isotonic solution, hypotonic solution, hypertonic
Ans : MAIN 2010
solution, water).
False. Raisins swell up when placed in a medium
which is hypotonic solution. Ans : COMP 2000

Hypertonic solution
101. Cells with shrunken protoplasm are called turgid.
109. The process by which molecules distribute
Ans : SQP 2022 themselves evenly with in the space they occupy
False. Cells with shrunken protoplasm are called is termed as (osmosis, diffusion, active transport,
flaccid. imbibition).
Ans : MAIN 2001

102. Leaves wilt due to exosmosis. Diffusion

Ans : MAIN 2018
110. Synthesized food in green leaves is transported
True through (phloem, xylem, pith).

103. Bleeding is because of root pressure. Ans : COMP 2017

Ans : COMP 2013

Phloem

False. Gultation is because of root pressure.

DIRECTION : Give biological reasons for :
104. The cell membrane is semi-permeable.
111. Salt and sugar are used in preserving food
Ans : SQP 2011
Ans : SQP 2003
True
Higher concentration of salt or sugar protects
the food from decay by bacteria and fungi due
DIRECTION : The statements given below are to plasmolysis. Hypertonic nature of such food
incorrect. Rewrite the correct statement by changing plasmolyses cells of bacteria and fungi and makes
the underlined words of the statements. them killed.

112. Some plants show wilting of their leaves during

105. Free movement of solutes in and out of the cell
mid day even when the soil is well watered.
takes place across the cell membrane.
Ans : MAIN 2010
Ans : MAIN 2017
During mid day the rate of transpiration is higher
Free movement of solute in and out of the cell
than the rate of absorption of water by roots
takes place across the cell wall.
hence show wilting.
106. The cell sap of root hair is Hypotonic.
113. On sprinkling common salt on grass growing in a
Ans : SQP 2018 lawn, the grass is killed.
Hypertonic Ans : SQP 2004

Surrounding water becomes hypertonic hence

water from root hair cells come out by process of
DIRECTION : Choose the correct alternative : exosmosis and cells get plasmolysed and die.

107. Marine fish when thrown under tap water bursts 114. Wilted lettuce leaves if kept in cold water become
because of (endosmosis, exosmosis, diffusion, crisp.
plasmolysis).
Ans : COMP 2010, 2003
Ans : MAIN 2002
Leaves of wilted lettuce are plasmolysed but when
Endosmosis. kept in cold water they get deplasmolysis and
become turgid and hence are crisp.
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 91

115. Potato cubes when placed in water become firm 122. The process of uptake of mineral ions against the
and increase in size. concentration gradient using energy from cell.
Ans : MAIN 2011 Ans : MAIN 2002

Because of endosmosis the cells become turgid. Active transport.

116. Root hairs become flaccid, when fertilizers are 123. Account for the wilted lettuce leaves become
added to the moist soil around it. crisp/firm when placed in cold water for a while.
Ans : SQP 2015 Ans : SQP 2010

Because exosmosis takes place from root hair Cold water being hypotonic helps in endosmosis.
cells. The cells of the lettuce leaves get deplasmolysis
and become turgid.
117. Transplanting of seedling to a flower bed in the
evening is better than doing so in the morning. 124. Identify and name the process of movement of
Ans : COMP 2002 molecules from a region of higher concentration
to a region of lower concentration.
Because temperature goes down, there is less
sunlight, rate of transpiration falls, less water is Ans : MAIN 2010
lost by seedling and during night roots get turgid Diffusion.
and push into the soil.
125. Plants growing in fertilized soil are often found to
118. Strips of potato placed in 50% sucrose solution wilt if the soil is not adequately watered.
appear soft and shriveled.
Ans : COMP 2001
Ans : MAIN 2011, 1996
If soil is fertilized and not well watered the
Water starts moving out in the outer concentrated concentration of soil solution becomes very high
sugar solution. After some time due to exosmosis and water moves out of root hair cells due to
potato strip becomes soft and shriveled due to exosmosis. If the process continues for a long time
loss of water as cells become flaccid. wilting will be observed.
119. Plants begin to die when excess of soluble 126. Explain the term root pressure.
fertilizers are added to the soil.
Ans : SQP 2010
Ans : COMP 2007
The pressure which develops in the cortical cells
Because of exosmosis, the root hair shrivel. of root and pushes the water and minerals into
120. Active Transport and Diffusion [significance in the xylem vessels.
plants] 127. Plants begin to die when excess of soluble
Ans : MAIN 2017 fertilizers are added to the ‘soil.
Active transport : The plant for the absorption of Ans : MAIN 2005
mineral salts such as nitrates against concentration Fertilizers along with soil water acts as hypertonic
gradient occurs from soil to root hair cells. solution. Exosmosis takes place and cells of the
Diffusion : For the exchange of respiratory gases. plant or crop die.
Removal of excess water by transpiration.
128. Weeds can be killed by adding salt to it.
121. Give suitable biological reasons for the following
statements : Ans : SQP 2007

Root hairs become flaccid and droop when excess When salt is added to the soil, water, near the
fertilizers are added to the moist soil around them. roots of weeds, becomes hypertonic. So exosmosis
Ans : SQP 2019 takes place as cell sap of weeds is of lower
concentration. Water moves out of the cells of
Excessive fertilizers make the soil hypertonic as weed and kills them.
compared to root hair cells. Exosmosis takes place
and root hair cells become flaccid due to which 129. The raisins swell up when kept in water.
they droop.
CH 3 : ABSORPTION BY ROOTS
Ans : MAIN 2021
DIRECTION : Choose the correct answer from each
Water being hypotonic solution, enters into of the four options given below:
the raisins when they are kept in water due to
endosmosis. 138. Term for mixing of two different molecules.
[diffusion, osmosis, imbibition, endosmosis]
130. Grapes shrink when kept in sugar solution.
Ans : MAIN 2014
Ans : COMP 2018
Diffusion
Plasmolysis takes place when grapes are kept in
sugar solution, so they shrink. 139. A cell shrink in a ______ solution.
[isotonic, hypotonic, hypertonic]
131. Pickles can be preserved by adding salt to it.
Ans : COMP 2019
Ans : SQP 2013
Hypertonic
By adding salt in pickles, the growth and
multiplication of bacteria can be prevented by
plasmolysis. DIRECTION : Define the following :

132. Farmers usually transplant seedings in a flower 140. Osmosis

bed in the evening.
Ans : MAIN 2007
Ans : COMP 2010
It is the movement of water (solvent) molecule from
In the evening, transpiration rate is less than the its higher concentration to its lower concentration
root pressure. So seedings remain intact and do through a semipermeable membrane.
not wilt.
141. Isotonic solution
133. Leaves of sensitive plant droop down on a touch.
Ans : SQP 2015
Ans : MAIN 2007
A solution whose concentration is equal to the
The stimulus of touch leads to loss of turgor concentration of the cell sap.
pressure at the base of the petioles of the sensitive
plant and as a result the leaves droop down. 142. Endosmosis
Ans : COMP 2010

DIRECTION : Give a scientific term for the following: The movement of water molecules into a cell
through a semipermeable membrane when it is
134. Loss of water through a cut stem. kept in a hypotonic solution.
Ans : SQP 2020
143. Turgor pressure
Bleeding
Ans : MAIN 2012

135. Sticking of water molecules to the surface of cell. It is the pressure which develops in the confined
Ans : MAIN 2023
part of an osmotic system due to osmotic entry of
water into it.
Adhesive force
144. Exosmosis
136. The condition when the cell is placed in a
hypotonic solution. Ans : COMP 2017

Ans : SQP 2018

The movement of water molecules out from a cell
when a cell is placed in a hypertonic solution.
Turgidity
145. Osmotic pressure
137. Movement of water through a semi-permeable
membrane. Ans : SQP 2020

Ans : SQP 2009

The pressure by which the water molecules tend
to cross the semi-permeable membrane.
Osmosis
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 93

146. Semipermeable membrane When a cell is placed in a hypertonic solution

water diffuses out of the cell and the protoplast
Ans : MAIN 2001
shrinks. The shrunken condition is called flaccid
A membrane which allows the movement of condition.
solvent molecules only across it.
9. Name the vascular tissues which conduct water
and translocate food.
DIRECTION : Answer the following :
Ans : SQP 2015

1. Mention one characteristic of roots for absorbing Xylem – conducts water.

water from the soil. Phloem – translocates food.
Ans : SQP 2025
10. How are root hairs adapted for absorption of
Root hairs have thin cell walls Enormous surface water from the soil?
area of roots Higher concentration of cell sap than
Ans : MAIN 2017
soil water
(a) Root hairs are thin walled.
2. A plasmolysed cell is shown along side. What is (b) The concentration of cell sap of root hair is
X? more than the soil water.
[water, hypertonic solution, vacuole, protoplasm]
11. What is ascent of sap?
Ans : COMP 2019
Ans : SQP 2018
Hypertonic solution
The process by which water absorbed by the roots
3. Movement of water out of a cell is is conducted to the upper part of the plant.
[Diffusion, Endosmosis, Osmosis, Exosmosis]
12. Give advantages of plasmolysis.
Ans : SQP 2004
Ans : MAIN 2022
Exosmosis
The advantages of plasmolysis are as follows.
4. Wilting is due to lack of (a) Weeds can be killed by adding salts in the
[sugar, salt, water, none] fields.
Ans : COMP 2008 (b) Addition of salt to pickles kills bacteria and
thereby the pickles preserve.
Water
13. What is wilting?
5. Active transport needs
[energy, osmotic pressure, root pressure, all of Ans : COMP 2002

them] Drooping of leaves due to loss of turgidity.

Ans : MAIN 2013
14. What is importance of turgidity to plants?
Energy.
Ans : SQP 2004

6. Write the name of the organ that transports water It helps in the opening and closing of stomata.
from the soil to other parts of the plant. Turgidity provides rigidity to soft tissues.
Ans : COMP 2016
15. What is the importance of osmosis to plants?
Root hair.
Ans : MAIN 2009

7. Define hypotonic solution. It helps in the absorption of water and cell to cell
Ans : SQP 2012 movement of water.
A solution whose concentration is less than the 16. How are mineral salts in plants absorbed?
cell sap is called as hypotonic solution.
Ans : SQP 2017

8. What is flaccid condition of a cell? Mineral salts are absorbed in the form of ions by
Ans : MAIN 2003 active transport.
CH 3 : ABSORPTION BY ROOTS

17. Name a solution whose concentration is greater Diffusion Osmosis

than that of cell sap.
(a) Movement of (a) Movement of
Ans : COMP 2019
the molecules of water or solvent.
Hypertonic solution. solute or solvent.
(b) Occurs with (b) Semipermeable
18. Leaves of sensitive plant wilt and droop down on
or without a membrane is
a slight touch. Why ?
semipermeable needed.
Ans : MAIN 2023 membrane.
Stimulus of touch leads to loss of turgor pressure
at the base of leaflets and petioles. 22. Active and Passive absorptions.
Ans : SQP 2007

DIRECTION : Distinguish between: The difference between Active and Passive

absorptions are as follows :
19. Plasmolysis and Deplasmolysis.
Active Absorption Passive Absorption
Ans : MAIN 2012
(a) It takes place (a) It takes place
The difference between Plasmolysis and from lower from higher
Deplasmolysis are as follows : concentration concentration
Plasmolysis Deplasmolysis to higher to lower
concentration. concentration.
(a) It takes place (a) It takes place
when a cell is kept when plasmolysed (b) Cell energy from (b) Cell energy is not
in a hypertonic cell is placed ATP is required. required.
solution. in a hypotonic
solution. 23. Endosmosis and Exosmosis.

(b) Shrinkage of (b) Swelling of Ans : SQP 2000

protoplast. protoplast. The difference between Endosmosis and Exosmosis

(c) Cells become (c) Cells become are as follows :
flaccid. turgid.
Endosmosis Exosmosis
20. Osmotic pressure and Turgor pressure. (a) It occurs when (a) It occurs when
a cell is placed a cell is placed
Ans : COMP 2016
in a hypotonic in a hypertonic
The difference between Osmotic pressure and solution. solution.
Turgor pressure are as follows : (b) Water moves into (b) Water. moves out
Osmotic Pressure Turgor Pressure the cell. of the cell.

(a) It develops due to (a) It is the pressure 24. Flaccid and Turgid conditions.
osmotic entry of exerted by the
water in a cell. cell contents on Ans : MAIN 2006

the cell wall. The difference between Flaccid and Turgid

(b) It helps in the (b) It helps the plant conditions are as follows :
absorption of in being erect.
Flaccid Condition Turgid Condition
water.
(a) It is a condition (a) It happens when
21. Diffusion and Osmosis. when a cell a cell is placed
is placed in in hypotonic
Ans : MAIN 2019
a hypertonic solution.
The difference between Diffusion and Osmosis are solution.
as follows :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 95

(b) Water is lost (b) Water enters Wall pressure Turgor pressure
from the plant into a cell due to The pressure exerted The pressure exerted
due to exosmosis. endosmosis. by the cell wall on the by the contents of the
contents of the cell. cell on the cell wall.
25. Osmosis and Plasmolysis.
Ans : MAIN 2004

The difference between Osmosis and Plasmolysis

are as follows : TWO MARKS QUESTIONS
Osmosis Plasmolysis
It is the movement of It is the shrinkage 29. Explain the term — Active transport.
water from its region of protoplasm when Ans : SQP 2025
of higher concentration a cell is placed in a
It is the movement of salt or ion across a cell
to its region of lower hypertonic solution.
membrane from lower to higher concentration by
concentration through
the use of energy.
a semi-permeable
membrane. 30. Define the following :
(i) Hypotonic solution.
26. Hypertonic and Hypotonic solutions. (ii) Active transport.
Ans : SQP 2007 Ans : MAIN 2009

The difference between Hypertonic and Hypotonic (i) Hypotonic solution - A solution having low
solutions are as follows : osmotic pressure or lower concentration of
solutes as compared to another solution.
Hypertonic Solution Hypotonic Solution
(ii) Active transport - Passage of substances
(a) A solution whose (a) A solution whose (ions or salts) from already low concentration
concentration is concentration is to their higher concentration (against
more than the cell less than the cell concentration gradient) by utilization of
sap. sap. energy of the cell.
(b) Its osmotic (b) Its osmotic
31. Differentiate diffusion and osmosis.
pressure is more. pressure is less.
Ans : MAIN 2015

27. Xylem and Phloem. The difference between Differentiate diffusion and
Ans : MAIN 2011 osmosis are as follows :
The difference between Xylem and Phloem are as Diffusion Osmosis
follows :
The free movement of The movement of
Xylem Phloem molecules of various water molecules from
substances (solid, the region of their
(a) Helps in the (a) Helps in the
liquid or gas) from the higher concentration
conduction transport of
region of their higher to the region of their
of water and prepared food.
concentration to the lower concentration
minerals.
region of their lower through a semi
(b) It is a dead tissue. (b) It is a living concentration when permeable membrane.
tissue. the two ate in direct
contact.
28. Wall pressure and turgor pressure.
Ans : COMP 2017
32. Explain the terms :
(i) Diffusion
The difference between Wall pressure and turgor (ii) Turgidity
pressure are as follows :
Ans : COMP 2010
CH 3 : ABSORPTION BY ROOTS

(i) It is the movement of molecules of a substance Ans : SQP 2021

from a region of high concentration to a region Plasmolysis is the shrinkage of protoplasm from
of lower concentration. the cell wall when a cell is placed in a hypertonic
(ii) Turgidity is the swelled up state of the cell solution. Preservation of jams is done by adding
due to absorption of water. sugar; fish, meat, etc. are preserved by adding salt
to them. This creates a hypertonic medium for
33. Explain the term plasmolysis. Give one application the microorganisms that are killed.
of this phenomenon in our daily life.
Ans : SQP 2005
38. What is transpiration pull?

Shrinkage of protoplast of a plant cell from its cell Ans : SQP 2010

wall under the influence of hypertonic solution Due to transpiration, water is lost from the leaves.
is called plasmolysis and the cell in this state This decreases the water potential. More water
is said to be limp or flaccid. This condition is molecules are pulled up due to cohesion of water
called flaccidity. Adding salt in pickles and sugar molecules. This pulling force is transpiration pull.
in jams, jellies preserve them from decaying by
plasmolysing the bacterial cell. 39. Demonstrate water absorption by roots.
Ans : MAIN 2018
34. Write the role of cohesive force in ascent of sap.
Take two test tubes – A and B. Fill both the test
Ans : COMP 2017
tubes with water. Insert a rooted balsam plant
Cohesive force is the force created due to mutual into test tube A. Add a drop of oil in both the
attraction between water molecules. Due to test tubes. Do not keep a plant in test-tube B. It
transpiration, a large quantities of water are lost. is observed that in a day or two the level of water
Water forms a continuous column in the xylem in test-tube A falls and not in test tube B. This
of the leaves to the xylem of the roots. Due to proves that roots absorb water.
cohesion, the water column does not break.
40. What is active transport in plants?
35. Rewrite the completed explanation by inserting
Ans : COMP 2021
the key word in the space indicated by.
Osmosis is the movement of water molecule from It is the process of movement of molecules from
its region of higher concentration to its region of a lower concentration to a higher concentration
lower concentration through a ‘^’ membrane. across the cell membranes. This requires energy
as the molecules move against the concentration
Ans : MAIN 2008
gradient.
Osmosis is the movement of water molecule from
its region of higher concentration to its region of 41. What is importance of diffusion in plants?
lower concentration through a semi-permeable Ans : MAIN 2017
membrane.
(i) Gaseous exchange takes place through
36. Write an experiment to prove that phloem stomata.
conducts food. (ii) The ions are absorbed by the simple diffusion
during passive salt intake.
Ans : SQP 2001

Take a potted plant. Cut a ring around the stem 42. What is total/evident plasmolysis and how it
deep enough to penetrate the phloem. After a few differs from incipient plasmolysis ?
weeks it is observed that the part of the stem above Ans : COMP 2005
the ring has grown in diameter and adventitious
The condition in which water from the cell is
roots have developed. This accumulation of food
removed completely due to exosmosis and no
proving that phloem conducts food/storage. Since
more shrinkage is possible in its protoplast is
food does not reach below the ring, the stem
called total/evident plasmolysis while primary
shrivells.
stage of plasmolysis in which protoplast just starts
37. Explain the term plasmolysis. Give one application shrinking away from cell wall is called incipient
of this phenomenon in our daily lives. plasmolysis.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 97

43. Give one example of osmosis occurring in human the basis of state of water.
body and a green leaf.
Ans : MAIN 2020
Ans : MAIN 2017
(i) To prove that phloem is responsible for
In human body, it is movement of water from conduction of food material.
body fluid into the blood. (ii) Transpiration – water vapour Guttation –
In green leaf, it is movement of water into the liquid water
mesophyll cells from the leaf veins.
50. Give reasons:
44. Can osmosis be regarded as diffusion ? (i) Why do people gargle with salt solution
during throat infection?
Ans : COMP 2009
(ii) Letuce leaves remain fresh in cold water.
Yes, it is a kind of diffusion occurring through
semipermeable membrane as the movement of Ans : SQP 2010

water molecules take place from their higher to (i) While gargling, bacteria comes in contact
their lower concentration. with salt solution. They are plasmolysed and
killed. Thus, it gives people some relief.
45. Why do plants growing in fertilized soil often (ii) Lettuce leaves when kept in cool water do not
found to wilt if the soil is not adequately watered? become dull or wilt as endosmosis takes place
Ans : MAIN 2017 and they remain fresh.
The fertilizers with inadequately watered soil 51. (i) Give two examples of turgor movements in
form a hypertonic condition so that it results in plant.
plasmolysis and hence the plant shows wilting. (ii) Give two examples of semi-permeable
membrane, other than cell membrane.
46. Give any four examples of semipermeable
membrane. Ans : MAIN 2001

Ans : SQP 2001 (i) (a) Wilting of leaves

(b) Opening and closing of stomata.
(i) Egg membrane
(ii) (a) Egg membrane (semi-permeable).
(ii) Cellophane paper
(b) Parchment paper (semi-permeable).
(iii) Parchment paper
(c) Goat bladder (semi-permeable).
(iv) Goats bladder
52. (i) What is the aim of the experiments in A and
47. What will happen if the experiment on osmosis is
B?
performed with a boiled potato ?
(ii) What happens when dry seeds are soaked in
Ans : MAIN 2013 water? Name the term used for it.
Osmosis will not take place and there will be
neither rise nor decrease in the level of sugar
solution in the osmoscope. This is because on
boiling cell membrane loses its semipermeability.

48. Why are the following used in experiments?

Cobalt chloride paper and goat bladder.
Ans : SQP 2009

Goat bladder is used in osmosis experiments as

it is semi-permeable membrane. Cobalt chloride Ans : COMP 2022
paper is used in transpiration experiments to find
out the rate of transpiration. (i) Experiment A demonstrates endosmosis in
raisins.
49. Answer the following questions: Experiment B demonstrates exosmosis in
(i) Why is the ring experiment conducted in grapes.
plants? (ii) Dry seeds when soaked in water and swolls
(ii) Differentiate transpiration and guttation on up. The term used is imbibition.
CH 3 : ABSORPTION BY ROOTS

THREE MARKS QUESTIONS (iii) Name and define the physical process being
investigated in this experiment.
Ans : MAIN 2001
53. Draw a neat, labelled diagram of a root hair.
(i) Cubes are placed in hypotonic solution so
Ans : SQP 2025 endosmosis takes place and cell becomes
Diagram of a root hair. turgid resulting in firmness and increase in
size.
(ii) Placed in sugar solution hence becomes soft
and decrease in size because of exosmosis.
(iii) Osmosis : It is the flow of water molecules
from the region of their higher concentration
to the region of their lower concentration
through a semipermeable membrane.

56. Match the columns:

Column A Column B
(i) plasma membrane (a) minerals
54. How does turgor help in opening and closing of (ii) root hair (b) bleeding
stomata?
(iii) phloem (c) unicellular
Ans : COMP 2014
(iv) cell sap (d) conduction of
Opening and closing of stomata is done with the food
help of guard cells. Each guard cell has a thick
(v) active transport (e) semi-permeable
outer wall and a thin inner wall. Guard cells
contain chloroplasts where photosynthesis is Ans : MAIN 2004
carried out. The osmotic pressure of the guard
(i)-(e), (ii)-(c), (iii)-(d), (iv)-(b), (v)-(a),
cells increases as water is absorbed from the
surrounding cells, thus the guard cells become 57. Match the following Column :
turgid. The outer wall stretches outwards and the
stomatal pore widens through which exchange Column I Column II
of gases takes place. At night, slowing down of (a) Plasmolysis (i) Active transport
photosynthesis process causes the guard cells to
loose water. The inner walls of the chloroplast of (b) Absorption (ii) Acts due to cell
the guard cells become flaccid and thus closes the of ions from sap on cell wall
stomatal pore. soil against
concentration
55. Potato cubes 1 cm in size were placed in two gradient.
containers, one containing water, the other (c) Turgor pressure (iii) Hypertonic
containing concentrated sugar solution. After medium
about 24 hours when the cubes were examined,
(d) Phloem (iv) Absorption of
then those placed in water were found to be firm
water by living
and had increased in size by a few millimeters.
or dead cells of
Those placed in concentrated sugar solution were
plants.
found to be soft and had decreased in size. Use
the above information to answer the questions (e) Imbibition (v) Translocation of
that follow : food
(i) Account for the firmness and increase in size
of the potato cubes which were placed in Ans : COMP 2008

water. (a) – (iii), (b) – (i), (c) – (ii), (d) – (v), (e) – (iv)
(ii) Account for the softness and decrease in size
of the potato cubes which were placed in the 58. (i) Define suction pressure.
sugar solution. (ii) Which condition is bidirectional and
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 99

unidirectional? Diffusion and osmosis. FIVE MARKS QUESTIONS

(iii) Write four significance of plasmolysis in our
daily life.
Ans : MAIN 2017
60. The figure given below shows the epidermal cells
of an onion bulb. This cell was then transferred to
(i) The pressure by which water is drawn into a a drop of sugar solution.
cell is called suction pressure.
(ii) Diffusion is bidirectional. Osmosis
unidirectional.
(iii) (a) Sucking leech can be removed from a
person by adding salt to the leech.
(b) Plants growing on the walkways can be
removed by adding salt to the plant roots.
(c) Jam, jellies, pickles can be preserved by
adding sugar and salt to them.
(d) Weedicides are used in crop fields to kill
the weeds.
(e) While gargling, bacteria are killed due to (i) Draw a well labelled diagram of the epidermal
plasmolysis. cell as it would appear after immersion in a
strong sugar solution.
59. Give reasons for the following : (ii) What scientific term is used for the changes
(i) We gargle with saline solution in case of as shown in (i) above ?
throat infection. (iii) What should be done to restore the cell back
(ii) Bacteria and fungi do not grow in pickles, to its original condition ?
jams, jellies and squashes. (iv) Give the scientific term for the recovery of the
(iii) The leaves of wilted lettuce if kept in cold cell as a result of the step taken in (iii) above.
water become crisp. (v) Define the term osmosis.
Ans : SQP 2007 Ans : SQP 2013

(i) Salt solution is hypertonic. When it comes (i)

in contact with bacteria in the throat, they
get plasmolysed and are killed which gives us
relief from the infection.
(ii) Pickles, jams, jellies and squashes are in
hypertonic solutions of either salt or sugar.
It causes plasmolysis in bacteria and other
microorganisms which cannot grow in such an
unfavourable environment or get killed. Thus
these food materials can be preserved for long
durations. (ii) Plasmolysis
(iii) Wilted lettuce has plasmolysed cells which (iii) Keep the cell immediately back in to water
are flaccid but when such leaves are kept in before the cell dies.
water, endomosis takes place and cells become (iv) Deplasmolysis
turgid. In such a condition, the leaves become (v) Osmosis is the movement of water molecules
crisp. from the region of their higher concentration
to the region of their lower concentration
through a semipermeable membrane.

61. Given below is the diagram of an apparatus set up

to study a very important physiological process :
(i) Name the process being studied.
(ii) Explain the process.
(iii) What change would you observe in the thistle
CH 3 : ABSORPTION BY ROOTS

funnel containing sugar solution after about (iv) Name two liquids that could be used in this
10 minutes ? experiment.
(iv) Is sugar solution hypertonic or hypotonic ? (v) Why did the level of the liquid in the vertical
(v) Explain why much salt is added to pickles. tube rise ?
Ans : COMP 2017

(i) The experiment demonstrates the process of

osmosis.
(ii) Transfer of water or solvent molecules from a
solution of lower concentration to a solution
of higher concentration through a semi-
permeable membrane is called osmosis.
(iii) 1. Helps in water absorption.
2. Helps in stomatal movements.
(iv) Distilled water and concentrated sugar
solution.
(v) The level of the liquid in the vertical tube
rises due to the entry of water into it through
the goat’s bladder by means of the process of
osmosis.
Ans : SQP 2010

(i) Osmosis 63. Given are the diagrams of a certain structure in

(ii) Osmosis in the diffusion of water molecules plants in two conditions.
through a semipermeable membrane from a (i) Name the structure shown.
dilute to a concentrated solution. (ii) Name the parts numbered 1 - 5.
(iii) The level of sugar solution in the stem of
thistle funnel rises due to the entry of water
from the beaker in the thistle funnel.
(iv) Hypertonic, as it draws water from the
beaker.
(v) When salt is added to pickles, it make
hypertonic solution. It draws water from the
microbes by exosmosis, plasmolysis them,
resulting in their death.

62. The diagram represents an experimental set up to

demonstrate a vital process. Study the same and (iii) What is the most apparent difference between
then answer the questions that follow : A and B in the structure shown ?
(iv) Describe the mechanism which brings about
the change in the structures depicted in A
and B.
Ans : MAIN 2012

(i) Stomata
(ii) 1 – Guard cell.
2 – Thick cell wall towards the stomatal
opening.
3 – Nucleus.
4 – Adjoining epidermal cell.
5 – Stomatal opening.
(i) Name the process. (iii) A shows an open stomata.
(ii) Define the above named process. B shows a closed stomata.
(iii) Mention two advantages of this process to the (iv) The mechanism of opening and closing of
plant. stomata : The opening and closing of stomata
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 101

is regulated by the amount of water and diagram and answer the questions that follow :
solutes present in the guard cells. The guard
cells have thick inner wall facing the opening
and thin outer wall on the opposite side. Their
cytoplasm contains chloroplasts. During the
day, the guard cells begin photosynthesis
and the sugar produced during the process
increases the osmotic pressure which draws in
water from the adjoining cells by endosmosis.
Hence, the guard cells become turgid and
bulge outwards due to their thin outer walls,
thus widening the stomata. During stomatal
closure reverse change occur. (i) Name the parts labelled A, B, C and D.
(ii) The root hair cell is in a turgid state. Name
64. The apparatus arranged below signifies an and explain the process that caused this state.
important process: (iii) Mention one distinct difference between the
parts labelled A and B.
(iv) Draw a diagram of the above root hair cell as
it would appear when a concentrated solution
of fertilizers is added near it.
Ans : COMP 2011

(i) A - Cell wall, root hair, B - Cell membrane

C - Cytoplasm, D - Nucleus
(ii) Endosmosis; The entry of the water from
the soil into the root hair results in turgor
pressure and it become turgid.
(iii) Cell wall is permeable whereas cell membrane
is differentially semi-permeable.
(iv)

(i) Name the process.

(ii) Where does this process occur in plants ?
(iii) What solution is placed inside the dialysis
tubing ?
(iv) What happens to the level of the solution in
the capillary tube ?
(v) Define the process mentioned in (i) above.
Ans : MAIN 2013

(i) Osmosis.
(ii) In the root hairs of plants. 66. Study the diagram and answer the questions that
(iii) Strong sugar solution or the salt solution. follow :
(iv) The level in the capillary tube rises above. (i) Name the process being studied in the
(v) Osmosis is a physiological process that takes experiment.
place when two solutions having different (ii) Explain the process mentioned in (i) above.
concentrations or a solution and its pure (iii) Why is oil placed over water ?
solvent are separated by a semi-permeable (iv) What do we observe with regard to the level
membrane. of water when this set up is placed in
(1) bright sunlight
65. The diagram below represents a layer of epidermal (2) humid conditions
cells showing a fully-grown root hair. Study the (3) windy day ?
CH 3 : ABSORPTION BY ROOTS

(iii) What is the function of part labelled A ?

(iv) Mention two structural features of A, which
help in the function of mentioned in (iii)
above.
(v) Where is this structure likely to be found in a
leaf ?
(vi) The above structure helps in the process of
transpiration. Explain the term transpiration.
(vii) How many other cells are found surrounding
this structure as seen in the diagram ?
Ans : MAIN 2009

(i) (A) Guard cell, (B) Stoma/stomatal pore

(ii) The biological term for the structure is
Stomata.
(v) Mention any three adaptations found in
(iii) The function of part labelled A is it helps in
plants to overcome the process mentioned in
opening of stomata due to turgidity during
(ii) above.
daytime and closing of stomata due to
Ans : SQP 2011 flaccidity at night.
(i) Transpiration (iv) Two structural features of A is that
(ii) The loss of water in the form of water (a) Guard cells outer wall is thin and can be
vapour from aerial parts of the plant is called stretched.
transpiration. (b) It consists of chloroplast which helps to
(iii) To prevent loss of water by evaporation. increase sugar level in guard cells making
(iv) (1) Transpiration is accelerated and level of it hypertonic so that it can absorb water
water fall down/lowered. from adjoining cells and become turgid.
(2) Low humidity transpiration increases and (v) This structure is found on the upper and
water level falls down and vice versa. lower epidermis of leaves.
(3) Increases the rate of transpiration and (vi) Transpiration is the loss of water in the form
lowers the water level. of water vapour from the aerial exposed parts
(v) Three adaptations are : of the plant.
(a) Thick cuticle (vii) Five other cells are found surrounding this
(b) Sunken stomata structure as seen in the diagram.
(c) Loss of leaves
68. The figure given below is a diagrammatic
67. The diagram below represents a structure found representation of a part of the cross section of the
in a leaf. Study the same and answer the questions root in the root hair zone. Study the same and
that follow : then answer the questions that follow :

(i) Name the parts indicated by the guidelines 1

to 4.
(ii) Which is the process that enables the passage
of water from the soil into the root hair?
(i) Name the parts labelled A and B. (iii) Name the pressure that is responsible for the
(ii) What is the biological term for the given movement of water in the direction indicated
structure. by the arrows. Define it.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 103

(iv) Due to an excess of this pressure sometimes its original condition? Mention the scientific
drops of water are found along the leaf term for the recovery of the cell.
margins of some plants especially in the early (v) State any two features of the above plant cell
mornings. What is the phenomenon called ? which is not present in animal cells.
(v) Draw a well labelled diagram of the root hair
Ans : MAIN 2017
cell as it would appear if an excess of fertilizer
is added to the soil close to it. (i) The state of the cell is Plasmolysed
(ii) Cell membrane
Ans : MAIN 2016
(iii) 1. Cell wall
(i) 1 - Root hair 2. Strong sugar solution
2 - Soil particles 3. Cell membrane
3 - Xylem 4. Nucleus.
4 - Cortex cells (vi) By putting it in hypotonic solution/water.
(ii) Osmosis, water potential gradient. The scientific term for the recovery of the cell
(iii) Suction pressure or hydrostatic pressure. It is deplasmolysis.
is the pressure that develops in the confined (v) (i) Cell wall
part of an osmotic system due to osmatic (ii) Vacuole.
entry of water into it.
(iv) Guttation 70. A candidate in order to study the process of
(v) osmosis has taken 3 potato cubes and put them in
3 different beakers containing 3 different solutions.
After 24 hours, in the first beaker the potato cube
increased in size, in the second beaker the potato
cube decreased in size and in the third beaker
there was no change in the size of the potato
cube. The following diagram shows the result of
the same experiment:

69. The diagram given below represents a plant cell

after being placed in a strong sugar solution. (i) Give the technical terms of the solutions used
Study the diagram and answer the questions that in beakers, 1, 2 and 3.
follow: (ii) In beaker 3 the size of the potato cube remains
the same. Explain the reason in brief.
(iii) Write the specific feature of the cell sap of
root hairs which helps in absorption of water.
(iv) What is osmosis?
(v) How does a cell wall and a cell membrane
differ in their permeability?
Ans : COMP 2014

(i) (1) Hypotonic, (2) Hypertonic, (3) Isotonic.

(ii) The solution in the beaker is isotonic (outside
(i) What is the state of the cell shown in the solution of same concentration as the cell
diagram? sap). So, osmosis does not take place.
(ii) Name the structure that acts as a selectively (iii) Root hairs have cell sap which has a higher
permeable membrane. concentration than the soil water. Root hairs
(iii) Label the parts numbered 1 to 4 in the also contain plasma membrane which allows
diagram. water molecules to pass through it. So, root
(iv) How can the above cell be brought back to hairs absorb water from the soil.
CH 3 : ABSORPTION BY ROOTS

(iv) It is the movement of water molecules from the water rises in the plants after cutting
their higher concentration to their lower section of leaf and stem.
concentration through a semi-permeable (v) What would happen, if the experimental set-
membrane. up was placed in dark in cupboard ?
(v) Cell wall is freely permeable. Cell membrane (vi) What precautions would you follow for the
is semi-permeable. success of the experiment ?

71. Given diagram shows an apparatus set-up to

study a very important physiological process:

Ans : SQP 2023

(i) Ascent of sap.

(i) Name the process being studied. (ii) The upward transport of water along with
(ii) What change would you observe in the thistle dissolved minerals from the roots to the aerial
funnel containing sugar solution after about parts of the plants.
10 minutes? (iii) Root pressure in case of herbaceous plants
(iii) Is sugar solution-hypersonic or hypotonic? and transpiration pull in case of large trees.
(iv) Name the part of the plant cell which is (iv) Xylem elements.
represented by the sugar solution. (v) There will be no rise of water due to the absence
(v) Explain why much salt is added to pickles. of conditions that favour transpiration.
Ans : SQP 2010 (vi) Balsam should be cut under water to avoid
the entry of air bubbles in the xylem channels.
(i) Osmosis.
1. An oblique cut should be given at the
(ii) The level of the sugar solution in the thistle
base of shoot.
funnel will rise.
2. Take fresh shoot or freshly uprooted
(iii) Sugar solution is hypertonic solution.
plants of balsam or petunia with white
(iv) Cell sap in the vacuole.
flowers.
(v) Salt acts as a hypertonic medium. It prevents
the multiplication of bacteria by the method 73. Given below is the diagrammatic representation of
of and plasmolysis, so that pickles can be the transverse section of a part of a plant. Study
preserved. the same and answer the questions that follow :
(i) Name the part of the plant that is shown.
72. The diagram given below represents an
(ii) Label the parts 1 to 6 indicated in the
experimental set up to demonstrate vital process.
diagram.
The veins of the leaves have become coloured
(iii) Write the functions of parts 3 and 5.
after some time. Study the same by cutting thin
sections of stem and leaves and then answer the
questions that follow :
(i) Name the process.
(ii) Define the above named process.
(iii) What are the processes responsible for the
rise of water in herbaceous plants and large
trees ?
(iv) Suggest the name of pathway through which
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 105
Ans : MAIN 2003
(v) Limb A of U tube is comparable to the root
(i) The part of the plant that is shown in a cross- hairs.
section of a young root.
(ii) 1. Root hair 75. In the figures given below, ‘A’ shows a cell in the
2. Epidermis normal state and ‘B’ shows the same cell after
3. Cortex leaving it in a certain solution for a few minutes :
4. Endodermis (i) Describe the change which has occurred in
5. Phloem the cell as seen in B.
6. Meta xylem (Xylem). (ii) Give the technical terms for the condition of
(iii) Part - 3 : Function of Cortex : (a) Storage of the cell as reached in B and as it was in A.
starch grain. (iii) Define the process which led to this condition.
Conduct water from root hairs to the inner (iv) Was the solution isotonic, hypotonic or
tissues. hypertonic in which the cell was kept ?
Part - 5 : Function of Phloem : (v) How can the cell in ‘B’, be brought back to its
(a) Conduction of food. original condition ?
(b) Storage of organic food matters. (vi) Name the parts numbered 1 to 3.
(c) Lateral translocation of food.
The phloem cells conduct prepared food made
in the leaves to the storage regions.

74. Given diagram is of an experiment just at the

start. Study the diagram carefully and then
answer the question that follow :
(i) What phenomenon is intended to be shown
by this experiment ?
(ii) Which limb of U tube contains more concen-
trated solution, A or B ?
(iii) Why have the two kinds of molecules been
shown in different sizes ?
Ans : COMP 2020

(i) The protoplast shrinks and leaves the cell

wall as it is plasmolysed.
(ii) A - Flaccid
B - Turgid
(iii) A cell when placed in hypertonic solution
shrinks due to contraction of protoplast.
(iv) It was Hypertonic solution in which the cell
was kept.
(v) Keep the cell in Hypotonic solution.
(vi) 1. Cell wall
(iv) Why is the membrane separating the 2. Cell membrane
two solutions labelled as semipermeable 3. Chloroplasts.
membrane ? 76. The given figure shows a root hair:
(v) Which limb of U tube is functionally
comparable to the root hairs of a plant ?
Ans : SQP 2011

(i) Osmosis
(ii) A
(iii) Their molecular sizes are different. Sucrose
has large sized molecules.
(iv) It permits movement of only water molecules (i) Label the parts 1 to 4.
Ans. to pass through it. (ii) What is the role of part 4?
CH 3 : ABSORPTION BY ROOTS

(iii) Why is the root hair one-celled? (v)

(iv) What will happen to the root hair if some
fertilizer is added to the soil near the root Plant cell Animal cell
hair? (i) Cell wall is present. Cell wall is absent.
Ans : SQP 2017 (ii) Vacuole is large. Vacuole is
(i) 1. Nucleus absent. Even if
2. Vacuole, present, are small,
3. Cell wall temporary and are
4. Cell membrane concerned with
(ii) Part 4 is cell membrane. It is semi-permeable either excretion or
in nature and it allows only certain substances secretion.
dissolved in water to pass through it. (iii) Cytoplasm is In an animal cell,
(iii) It is an extension of epidermal cell. pushed to the the cytoplasm is
(iv) It becomes limp because water will move periphery region denser, granular
out, as soil water becomes hypertonic by the and forms a thin and occupies
addition of fertilizer. lining with the cell greater space in the
wall. cell.
77. The diagram below represents a plant cell after
being placed in a strong sugar solution. Guidelines
78. The figure represents a tree in which a ring of bark
1 to 5 indicate the following :
was removed. After a season, a swelling appeared
1. Cell wall
on the bark above the ring while the bark below
2. Strong sugar solution
shrivelled up.
3. Protoplasm
4. Large vacuole
5. Nucleus.

Study the diagram and answer the questions that

follow :
(i) What is the state of the cell shown in the
diagram ?
(ii) Name the structure which acts as a selectively
(i) Account for the swelling in the bark above
permeable membrane.
the ring.
(iii) If the cell had been placed in distilled water
(ii) Account for the shrinking of the bark below
instead of strong sugar solution, which feature
the ring.
would not have been present ?
(iii) Name the tissue that distributes food in
(iv) If the cell in the diagram possessed
plants.
chloroplasts, where would these be present ?
(v) Name any one feature of this plant cell which Ans : MAIN 2010
is not present in animal cells. (i) The swelling above the ring takes place due
Ans : SQP 2004 to the accumulation of food, because phloem
takes the food till the part above the ring.
(i) Plasmolysed cell.
(ii) The shrinkage of the bark below the ring
(ii) Cell membrane.
takes place due to the absence of food as
(iii) The membrane and cell wall cannot be
phloem has been removed and food does not
distinguished from one another.
reached the part below the ring.
(iv) The cytoplasm itself appears green due to the
(iii) Phloem.
presence of chloroplast.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 107

79. A complete ring of bark was removed from a tree Ans : SQP 2013

as shown in the figure A. The tree continued to (i) After an hour or so in A, the level of sugar
live and after about one month it appeared as B. solution in the cavity of carrot will rise while
in B no change will take place.
(ii) The reason for the above change in A is
that carrot is raw so it is semi-permeable
membrane, living and osmosis takes place,
while B, the carrot is boiled and is dead so
plasma membrane loses its semi-permeability
and osmosis does not take place.
(iii) Control experiment is B with boiled carrot.
(iv) Exosmosis will take place and the level of
water in the beaker will increase.
(i) Account for the swelling in the bark above 81. The given figure shows the diagrammatic
the ring. representation of an RBC kept in three different
(ii) Account for the shrinkage of the bark below kinds of solutions:
the ring.
(iii) Name the tissue that distributes food in
plants.
(iv) Name the tissue that distributes water in
plants.
Ans : MAIN 2017

(i) Due to removal of ring of bark the phloem

was removed. Phloem conducts food from
(i) Name the three solutions in which the RBCs
leaves to other parts of the plants. The food
are kept.
material gets accumulated at the cut site
(ii) What changes take place to the RBCs after
resulting in swelling.
sometime?
(ii) The part of the plant below the ring does not
(iii) Give reasons for the changes.
get food hence it shrinks.
(iii) Phloem Ans : SQP 2018
(iv) Xylem (i) A – Isotonic solution
B– Hypotonic solution
80. The given figure is the diagrammatic
C– Hypertonic solution
representation of an experiment to demonstrate
(ii) In
A– cell shape and size remain unchanged.
osmosis by carrot osmoscope:
In
B – cell enlarges or bursts.
In
C – cell shrinks in size.
(iii) A– Cell was kept in isotonic solution so no
movement of water or solvent molecules.
B – Cell was kept in hypotonic solution so
water enters into the cell and it enlarges.
C – Cell was kept in hypertonic solution
so water moves out of the cell and gets
shrunken.

(i) What will happen in A and B after an hour

82. A thin strip of epidermal cells of a leaf was
or so?
observed in a drop of water. They all looked
(ii) Give reason for the difference in observations
turgid and normal.
made in A and B.
(i) Draw a diagram of such a cell.
(iii) What is the control experiment?
(ii) Draw the diagram of the cell if this strip is
(iv) What would happen if dilute sugar solution
transferred to a strong concentrated solution
was placed inside the cavity of the carrot and
of sugar.
strong sugar solution was kept in the beaker?
CH 3 : ABSORPTION BY ROOTS

(iii) What will you do to bring these cells back to 84. In the figure, A shows a cell in the normal state
their original condition ? and B shows the same cell after leaving it in a
(iv) Name the condition observed in part (iii) certain solution for a few minutes:
above and then define it.
Ans : SQP 2017

(i)

(ii)
(i) Describe the change which has occurred in
the cell as seen in B.
(ii) Give the technical terms for the condition of
the cell as seen in B and in A.
(iii) Define the process which led to this condition.
(iv) What was the solution – isotonic, hypotonic
or hypertonic in which the cell was kept?
(iii) Keep these cells in water or hypotonic (v) How can the cell in B be brought back to its
solution. original condition?
(iv) Deplasmolysis. (vi) Name the parts numbered 1 to 3.
The recovery of the protoplasm when a
Ans : SQP 2011
plasmolysed cell is placed in a hypotonic
solution is called deplasmolysis. (i) The protoplast shrinks away from the cell
wall due to plasmolysis.
83. The figure represents a plant cell after being (ii) Flaccidity – figure B.
placed in a strong sugar solution. Turgidity – figure A.
(iii) When a cell is placed in a hypertonic
solution, shrinkage of protoplasm occurs.
This phenomenon is called plasmolysis.
(iv) Hypertonic.
(v) By keeping the cell in a hypotonic solution,
the cell will restore back to its originate
structure.
(i) Label the parts 1 to 5. (vi) 1. Cell wall
(ii) What is the state of cell shown in the figure ? 2. Cell membrane
(iii) Name the structure which acts as a semiper- 3. Chloroplast.
meable membrane. 85. The given diagram represents an experimental
(iv) If the cell in diagram possessed chloroplasts, set-up to demonstrate a vital process. Study the
where would these be present ? same and then answer the questions that follow :
Ans : MAIN 2021 (i) What would you observe in the experimental
set-up after an hour or so ?
(i) 1 – Cell wall
(ii) What control experiment can be set-up for
2 – Strong sugar solution
the above experiment ?
3 – Protoplasm
(iii) Keeping in mind the root hair cell and its
4 – Central Vacuole
surrounding, name the part that corresponds
5 – Nucleus
to :
(ii) Plasmolysed
(a) Concentrated sugar solution;
(iii) Cell membrane
(b) Parchment paper ;
(iv) Cytoplasm
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 109

(c) Water in the beaker. (iii) If a cell is placed in a concentrated cane

(iv) Name any other substance that can be used sugar solution, plasmolysis takes place. If
instead of parchment paper in the above the plasmolysed cell is placed in water,
experiment. deplasmolysis takes place and the call regains
(v) Mention two advantages of this process to the its state.
plant. (iv) Osmosis helps in the absorption of water by
root hairs. This helps in equal distribution of
Ans : MAIN 2018
water from one cell to other.
(i) After an hour or so, the level of liquid in the
vertical tube would rise. 87. The apparatus shown was set up for an experiment.
(ii) The control is to take water both in the After some time the level of the liquid in the
vertical tube and in the beaker. vertical section increased:
(iii) (a) Cell sap (i) What process does the experiment
(b) Plasma membrane/Cell membrane demonstrate?
(c) Soil water. (ii) Name two liquids that could be used in this
(iv) Goat’s bladder, Visking’s bag. experiment.
(v) (a) Absorption of water by root hairs. (iii) Why did the level of the liquid in the vertical
(b) To provide turgidity to cells. tube rise ?
(iv) Explain how the process named in (i) affects
86. (i) The given diagram is of a root hair. On the a protozoan such as Amoeba.
diagram, name the parts numbered 1 to 5. (v) Give one example in plants in which the above
process occurs and what is the advantage of
this to plants.

(ii) What role is played in the uptake of water

into the root hair by the plants numbered 1,
2 and 3 ?
(iii) What would hapifen if living cells of a plant
were placed first in a strong solution of cane
sugar and then in water ? Ans : SQP 2021
(iv) Of what use is osmosis to the growing plant? (i) Osmosis.
Ans : COMP 2019 (ii) 1. Salt solution; 2. Water.
(iii) The vertical tube contains sugar solution
(i) 1. Cell wall
and is separated from pure water by a semi-
2. Cell membrane
permeable membrane. So, osmosis occurs and
3. Vacuole
the level of the solution in the vertical tube
4. Cytoplasm
rises.
5. Nucleus.
(iv) Amoeba is a unicellular organism and lives
(ii) 1. Cell wall : It is freely permeable.
in water. It contains plasma membrane. So,
2. Cell membrane: It allows only water to
osmosis takes place and water enters into
pass through. It is a semi-permeable
the cell. To prevent the bursting of the cell,
membrane.
Amoeba possesses contractile vacuole that
3. Vacuole : It contains cell sap. The
throws out unwanted substances.
concentration of cell sap is more than soil
(v) Root hair – Osmosis helps in the absorption
water. So, endosmosis takes place.
of water.
CH 3 : ABSORPTION BY ROOTS

88. Given below is the diagram of an experiment just 89. The given diagram represents the result of an
at the start. Study the diagram carefully and experiment conducted on two freshly taken leafy
answer the following questions: shoots of a herbaceous plant. The lower ends of
the shoots are dipped in ordinary water.
(i) What is the aim of the experiment?
(ii) Some parts of the stem in both the shoots
have been removed. Name the conducting
tissue in shoot A and in shoot B that has
been removed.
(iii) What are the results of the experiment?

(i) What phenomenon is intended to be shown

by this experiment?
(ii) Which limb of the U-tube contains more
concentrated sucrose solution – A or B?
(iii) Why have the two kinds of molecules been
shown in different sizes?
(iv) Why is the membrane separating the
two solutions labelled as semi-permeable
membrane? Ans : COMP 2009

(v) Which limb of the U-tube (A or B) is (i) The aim of the experiment is to show that
functionally comparable to the root hairs of a conduction of water in plants takes place
plant? through xylem.
(vi) Redraw the diagram to show the result of the (ii) In shoot A, phloem has been removed. In
experiment after a few hours. shoot B, xylem has been removed.
Ans : MAIN 2006 (iii) In shoot B, xylem has been removed so the
leaves show wilted appearance. But in shoot
(i) Osmosis. A, xylem has not been removed and the leaves
(ii) Limb A in the U-tube has more concentration show turgid appearance.
of sucrose solution.
(iii) To represent solvent and solute particle: 90. The given figure shows an experimental process:
Bigger – Solute; Smaller – Solvent. (i) Name the process.
(iv) The membrane separating the two solutions (ii) Define the above mentioned process.
allows only solvent molecules to pass through (iii) What change will you observe after some
it. time? Water
(v) Limb A is functionally comparable to the (iv) Give one importance of this process to plants.
root hairs of a plant.
(vi)

Ans : SQP 2013

(i) Diffusion
(ii) The movement of molecules of a substance
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 111

from their higher concentration to their lower (iv) Is the cell given above a plant cell or an
concentration. animal cell? Give two reasons in support of
(iii) The colour of water will change to purple your answer as evident from the diagram.
because the molecules of KMnO4 will evenly (v) What would you do to bring this cell back to
distribute among the empty space of water its original condition?
due to diffusion.
Ans : MAIN 2015
(iv) Carbon dioxide and oxygen from the
atmosphere diffuse through stoma. (i) Plasmolysis
(ii) Hypertonic
91. Write an experiment to demonstrate transpiration (iii) 1. Nucleus
pull. 2. Chloroplast,
Ans : SQP 2020
3. Vacuole
4. Hypertonic solution
(iv) Plant cell.
Reasons are:
1. presence of cell wall.
2. presence of chloroplast.
(v) By keeping the cell in hypotonic solution and
deplasmolyse it.

93. The figure given is a diagrammatic representation

of a part of the cross-section of the root in the
root hair zone. Study the same and then answer
the questions that follow:

Fit a leafy shoot in a vertical tube filled with

water. Keep the lower end of the tube in mercury.
Keep the set-up undisturbed for sometime. It is
seen that mercury will rise up in the vertical tube
to a certain height due to transpiration pull.

92. Given below is the diagram of a cell as seen under

the microscope after having been placed in a
solution:
(i) Name the parts indicated by guidelines ‘1’ to
‘5’.
(ii) Is the root hair cell unicellular or multicellular?
(iii) Draw a labelled diagram of the root hair cell
as it would appear if some fertilizer is added
to the soil close to it.
(iv) Name the process responsible for the entry
of water molecules from the soil into Al and
then into A2.
(v) What pressure is responsible for the movement
of water in the direction indicated by arrows?
(vi) How is this pressure set up?
Ans : MAIN 2007

(i) What is the technical term used for the state/ (i) 1. Root hair
condition of the cell given above ? 2. Soil particles
(ii) Give the technical term for the solution in 3. Xylem
which the cell was placed. 4. Cortical cells/Parenchyma cells/Cortex
(iii) Name the parts numbered 1 to 4. 5. Nucleus.
(ii) Unicellular
CH 3 : ABSORPTION BY ROOTS

(iii) Diagram based questions

(iv) Endosmosis (cell to A1), Osmosis (cell to cell
A2).
(v) Root pressure, Osmotic pressure.
(vi) Due to the alternate turgidity and flaccidity
of the root hair cell and the cortical cell, the
pressure is maintained and water is sucked
up. (cohesive and adhesive force) Study the diagram and answer the questions that
follow:
94. Study the diagram given and answer the questions (i) What is the state of the cell shown in the
that follow: diagram?
(ii) Name the structure which acts as a selectively
permeable membrane.
(iii) If the cell had been placed in distilled water
instead of strong sugar solution which feature
would reappear.
Ans : COMP 2010

(i) It is a plasmolysed cell.

(ii) Cell membrane acts as selectively permeable
membrane.
(iii) Large vacuole.

CASE BASED QUESTION

96. Ravi is studying how water and minerals affect

(i) Explain the physiological process being plant growth in different soils. He observes
studied. healthier growth in plants with sufficient water
(ii) What will be observed in the two test tubes and minerals compared to those in dry soils.
after two to three days? 1. How is water involved in photosynthesis, and
(iii) Give a reason for your answer in (ii) above. why is it essential for plants?
(iv) Why is the surface of water covered with oil? 2. What is the role of mineral nutrients in plant
(v) State the purpose of setting up test tube B. growth?
3. How does water aid in transpiration, and why
Ans : SQP 2011
is it important for plant cooling?
(i) Absorption of water by the roots. 4. What happens to plant cells when deprived of
(ii) After two days, it is seen in test tube ‘A the water, and how does it affect stomata?
water level will fall and in test tube ‘B’ water
Ans :
level remains the same.
(iii) In test tube ‘A, the plant transpires and 1. Water provides the electrons needed for
absorbs water, so water level falls whereas test photosynthesis and releases oxygen during
tube ‘B’ acts as a control and no absorption the process.
takes place since plant is not kept in it. 2. Mineral nutrients help in growth and
(iv) To prevent the evaporation of water. metabolism, absorbed by roots as ions.
(v) Test tube ‘B’ acts as a ‘control’. 3. Water is lost during transpiration, cooling the
plant and aiding nutrient movement.
95. The figure represents a plant cell after being 4. Without water, cells lose turgidity, causing
placed in a strong sugar solution. Guidelines 1 to stomata to close and reducing photosynthesis.
5 indicate the following:
1. Cell wall; 2. Strong sugar solution; 3. 97. Sana is observing the impact of water and minerals
Protoplasm; 4. Large vacuole; 5. Nucleus. on plant growth in her school garden. She notices
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 113

that well-watered plants with adequate minerals Ans ::

are taller and greener, while those lacking water 1. Diffusion
or minerals show wilting and yellowing of leaves. 2. Kinetic energy
1. How does water contribute to the process of 3. Equal concentration
nutrient transport in plants? 4. Spreads molecules
2. What role do minerals play in the production
of plant enzymes? 100. Aditi is studying the process of osmosis in her
3. How does the lack of water affect the opening biology class. She learns that water molecules
and closing of stomata? move from an area of higher concentration to
4. What impact does a deficiency of minerals lower concentration through a semipermeable
have on plant leaves? membrane. She is also introduced to the concept
of osmotic pressure and the different types of
Ans : membranes involved in this process.
1. Transport 1. What is the movement of water molecules
2. Enzymes through a semipermeable membrane called?
3. Closing 2. What is the pressure required to prevent a
4. Yellowing solution from gaining more solvent molecules
during osmosis?
98. A student, Ankit, is studying how different 3. Give an example of a semipermeable
materials, such as seeds and wood, absorb water membrane.
and increase in volume. He learns that this process 4. What type of membrane is the cell membrane
is called imbibition, and it creates significant classified as?
pressure as the materials swell. Ans :
1. What is the movement of water into
substances like seeds called? 1. Osmosis
2. What happens to the volume of imbibants 2. Osmotic pressure
when they absorb water? 3. Parchment paper
3. What is the pressure created during imbibition 4. Differentially permeable
called?
101. Rohan is studying tonicity and how solute particles
4. Which substances are involved in the process
affect the tension in a system. He learns about
of imbibition?
three types of solutions: isotonic, hypotonic, and
Ans : hypertonic and how they influence the movement
1. Imbibition of water in and out of cells.
2. Increases 1. What is the term for the tension developed in
3. Imbibitional pressure a system due to solute particles?
4. Imbibants 2. Name the type of solution where the
concentration of solutes is the same inside
99. Meena is learning about how molecules move in and outside the cell.
her biology class. She observes that molecules 3. What type of solution causes water to move
move from an area of higher concentration to into the cell, leading it to swell?
an area of lower concentration, a process called 4. What type of solution causes water to leave
diffusion. This movement is driven by the kinetic the cell, making it
energy of the molecules and continues until the Ans :
concentration is equal throughout the space
1. What is the process of molecules moving from 1. Tonicity
a higher to a lower concentration called? 2. Isotonic
2. What force drives the movement of molecules 3. Hypotonic
during diffusion? 4. Hypertonic
3. When does the movement of molecules during
102. Suman is studying how water moves through
diffusion stop?
plants. She learns that root pressure helps push
4. How does diffusion help in the cell's
water upward from the roots, and the process
protoplasm?
by which water and minerals are transported to
CH 3 : ABSORPTION BY ROOTS

the aerial parts of the plant is called ascent of

sap. This movement occurs through the xylem
due to several forces, including root pressure and
transpiration pull.
1. What is the pressure developed in roots to
push sap upwards called?
2. What is the process of water transport from
roots to aerial parts of the plant called?
3. Through which plant tissue does the ascent of
sap occur?
4. Name one force responsible for the ascent of
sap besides root pressure.
Ans :
1. Root pressure
2. Ascent of sap
3. Xylem
4. Transpiration pull

www.nodia.in
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 115

CHAPTER 4
TRANSPIRATION

as “Turgor operated valves”. Generally stomata

SUMMARY are open during the day time and closed at night.
But in succulents like cacti stomata closes during
Most of the water absorbed by the plants is lost day and opens at night.
by them in the form of vapours. Only a small
fraction (about 2%) is used for the maintenance
of their life. All these plants continuously absorb
water through their roots. This water is conducted
upward through stem and is distributed to all the
aerial parts including the leaves.

1. TRANSPIRATION
It is a vital process both to plants and environment
and consequently to humans. It creates suction
force which helps in ascent of sap. Close and Open Stomata

1.1 Types of Transpiration 2.1 Mechanism of Stomatal Transpiration

The following three types of transpiration are The opening of stomata is governed by the changes
recognized in plants : in the turgor of the guard cells and the epidermal
1. Cuticular transpiration : Cuticle is present on cells adjacent to the guard cells. Two important
the epidermis of leaves and herbaceous stem. theories were put forward to explain the changes
The loss of water in the form of vapours from that occur in osmotic pressure of the guard cells.
epidermal cells of leaves and herbaceous stem These theories are :
is said to be cuticular transpiration. 1. Starch " Sugar interconversion theory:
2. Lenticular transpiration : Lenticels are present Stomata open in light and close in dark. This
in the bark of woody (old) stem. These are is due to enzymatic conversion of starch into
permanent openings of plants. Transpiration sugar in light. Sugar increases the osmotic
occurring through these lenticels fall under concentration of cell sap of the guard cells
this category. with the result that they absorb more water
3. Stomatal transpiration : The stomatas are from the neighbouring epidermal cells and
present in the epidermis of leaves and green increases turgidity of the guard cells which
stems. The transpiration which takes place results in the opening of stomata. In dark,
from the stomatas of the leaves of plants is sugar is converted into starch and whole
called stomata transpiration. process is reversed leading to closure of
2. STOMATA stomata.
2. Active potassium ion transport mechanism:
These are minute pores in the epidermal layers According to this view, accumulation of
of the aerial parts of plants. They are more potassium ion in the guard cells (as occurs
abundant on leaves. A stoma is surrounded by in light) increases negatively the osmotic
two specialised epidermal cells called guard cells potential of guard cells, causing stomata to
which are of two different shapes. One with kidney open. In dark, potassium ion moves out of
shaped (as in dicot leaves) and other dumb bell the guard cells and their osmotic potential
shaped (as in monocot leaves). Stomatas are called becomes less negative. Thus, water moves
CH 4 : TRANSPIRATION

out of the guard cells and their turgidity 6. Carbon dioxide – Increase in concentration
decreases, causing closure of stomata. of carbon dioxide over the normal level
(0.03%) causes stomatal closure hence
decrease rate of transpiration.

2.3 Advantages of Transpiration

The advantages of transpiration are - Maintenance
of turgidity, promotion of uptake and translocation
of solutes, reduction of leaf temperature,
absorption of water, cooling effect, improvement
in the quality of fruits and hardening.

2.4 Disadvantages of Transpiration

The disadvantages of transpiration are – Wilting
injury, stunted growth, abscission of leaves and
expenditure of energy.
1. Cuticle
2. Upper epidermis 3. POTOMETER
3. Palisade tissue
A potometer is an apparatus designed to measure
4. Spongy parenchyma
the rate of water uptake by a cut shoot or young
5. Guard cell of stoma
seedling. It does not measure transpiration
2.2 Factors Affecting Transpiration directly, but assumes that most of the water taken
up by the plant is lost by transpiration. Several
The Factors affecting transpiration are as follows. types of potometers are available but commonly
(A) Internal Factors : Ganong’s, Darwin’s and Farmers potometers are
1. Leaf area – Larger surface area of leaves used. In all these potometers an air bubble is
means more transpiration introduced in the capillary through which water
2. Leaf structure – Presence of thick cuticle, is absorbed. The rate of movement of bubble
coating of wax, sunken stomata, compact over a fixed distance is noted. The comparison
mesophyll and reduction in number of of bubble movement under different conditions
stomata reduce the rate of tanspiration. gives the rate of transpiration under different
3. Rolling, twisting and curling – Reduces environmental conditions. To compare the rate of
the rate of transpiration because the transpiration from both surfaces of a dorsiventral
amount of radiation received by the leaf leaf (unequal transpiration) is measured by
is decreased. Ganong’s potometer.
4. Mucilage or latex – Presence of mucilage
and latex reduces the rate of transpiration.
5. Root shoot ratio – Rate of transpiration
increases with the increase in root shoot
ratio.
(B) External or Environmental Factors :
1. Light – Only up to a certain point, the
increase in light intensity will increase
the rate of transpiration.
2. Temperature – Transpiration increases
with the rise in temperature.
3. Atmospheric humidity – Transpiration is
greater, when humidity is low.
4. Wind – Increase in wind speed increases
transpiration. Gang’s Photometer
5. Atmospheric pressure – Transpiration rate
4. GUTTATION
increases with decrease in atmospheric
pressure. It is the exudation of water drops from the edges
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 117

or tips of leaves through hydathodes. This occurs 3. Permanently open structures seen on the barks of
due to high root pressure and low temperature. old woody stems :
It occurs in – garden nasturtium, colocasia, (a) Stomata
oats, tomato, potato, grass, sunflower, balsam, (b) Hydathodes
chrysanthemum, etc. (c) Lenticels
(d) Epidermal pores
5. BLEEDING
Ans : MAIN 2021
It is the exudation of sap from injured parts of
plants. It is also a manifestation of root pressure. Permanently open structures seen on the bark of
If an incision is made in the stem of a plant an old woody stem are called lenticels.
growing in well watered soil, xylem sap starts Thus (c) is correct option.
oozing out due to root pressure.
4. Transpiration is useful to the plant because it :
Exudation of milky latex in Calotropis and
(a) Creates a suction force for absorption of water
Euphorbia are the examples of bleeding.
from the soil
(b) Helps in Photophosphorylation
(c) Synthesises glucose
(d) Splits water molecules.
MULTIPLE CHOICE QUESTION
Ans : SQP 2021

A suction force is created by transpiration that

1. The process in which water is lost from the helps in the upward movement of water in the
margins of strawberry leaves is: plants. Certain hydrophilic salts are accumulated
(a) Osmosis (b) Imbibition on the surface of the leaves, which keeps the leaves
(c) Diffusion (d) Guttation moist. It maintains the turgidity of the cells and
Ans : MAIN 2024 helps in cell division.
Thus (a) is correct option.
Guttation is the exudation of water droplets from
the margins or tips of leaves of some vascular 5. Transpiration :
plants. It typically occurs at night. Special pore- (a) It is the loss of water in the form of droplets
bearing structures called hydathodes present on from the aerial parts of the plant.
the margins of the leaf allow this exudation. (b) It is the loss of water in the form of water
Thus (d) is correct option. vapour from the underground parts of the
plant.
2. Which one of the following helps In the opening
(c) It is the loss of water in the form of water
of stomata:
vapour from the aerial parts of the plant.
(a) Cobalt ions
(d) It is the loss of water in the form of water
(b) Potassium ions
vapour from all parts of the plant.
(c) Magnesium ions
(d) Aluminium ions Ans : COMP 2021

Ans : MAIN 2024 In plants, the loss of water in the form of vapour
is called transpiration.
Potassium ions (K+) play a significant role in the
Thus (c) is correct option.
regulation of stomatal opening and closing in plant
cells. When potassium ions are actively pumped 6. Cuticle on leaves :
into guard cells, they cause an osmotic uptake of (a) Prevents photosynthesis.
water, leading to increased turgor pressure within (b) Reduces transpiration.
the guard cells. This increased pressure causes the (c) Protects leaves from grazing animals.
guard cells to swell and the stomata pore to open, (d) Gives colour to leaves.
allowing for gas exchange and transpiration.
Conversely, the loss of potassium ions from guard Ans : SQP 2021

cells results in decreased turgor pressure, causing The waxy coat present on both sides of the leaf
the stomata to close. surface is called the cuticle. Cuticles prevent
Thus (b) is correct option. plants from extreme climates like drought and
save water. The transpiration through stomata
CH 4 : TRANSPIRATION

transpiration. Ans : COMP 2012

Thus (c) is correct option. The spines present on cacti represent the reduced
leaves. The leaf parts become modified into spines
39. .............. is used as an indicator for a demonstration in order to protect the plants from grazing animals
of transpiration. and excessive transpiration.
(a) Litmus paper Thus (d) is correct option.
(b) Cobalt chloride paper
(c) Both (a) and (b) 44. .............. are minute openings in the epidermal
(d) None of the above layer of leaves.
(a) Lenticels (b) Cuticle
Ans : MAIN 2021
(c) Stomata (d) Stroma
Dry cobalt chloride paper that is blue in colour
turns pink when it comes in contact with water. Ans : SQP 2017

Using this property of cobalt chloride paper we Stomata are minute openings in the epidermal
can demonstrate water loss during transpiration. layer of leaves.
Thus (b) is correct option. Thus (c) is correct option.

40. .............. is a device which measures the rate of 45. The tissue that conducts water.
water intake by a plant. (a) Phloem
(a) Manometer (b) Thermometer (b) Xylem
(c) Potometer (d) Lactometer (c) Companion cells
(d) Transfusion tissue
Ans : COMP 2023

A potometer, sometimes known as transpirometer, Ans : MAIN 2006

is a device used for measuring the rate of water The tissue that conduct and transport water in
uptake of a leafy shoot which is almost equal to plant body is xylem tissue.
the water lost through transpiration. Thus (b) is correct option.
Thus (c) is correct option.
46. Lenticels
41. A plant with sunken stomata. (a) They are present on the surface of leaves and
(a) Mango (b) Nerium stem.
(c) Neem (d) Shrubs (b) They are present on the surface of newly
formed woody stem.
Ans : MAIN 2014
(c) They are present on the surface of older leaves
Plants growing mostly in xerophytic conditions and old woody stem.
have sunken stomata where they need to reduce (d) They are present on the surface of hard, old
transpiration rate. Some plants with sunken woody stem.
stomata are Nerium, Pine, Acacia, etc.
Thus (b) is correct option. Ans : COMP 2017

Lenticels are found as raised circular, oval, or

42. Exudation of sap from injured parts. elongated areas on stems and roots. In woody
(a) Guttation plants, lenticels commonly appear as rough,
(b) Secretion cork-like structures on young branches. Lenticels
(c) Bleeding participate in gaseous exchange and transpiration.
(d) Active transport Thus (d) is correct option.
Ans : COMP 2010
47. Hydathodes
Exudation of sap in plants through the injured
(a) Located along the margin and on the upper
part is called bleeding. It happens because of
or lower surfaces of leaves.
the hydrostatic pressure produced due to an
(b) Located along the margin and on the upper
accumulation of water in the root cells.
or lower surfaces of leaves and green stem.
Thus (c) is correct option.
(c) Into pits on leaves margin which may be
43. Leaf modification in cacti to check transpiration. covered by multicellular hair.
(a) Thorns (b) Phylloclade (d) Present on the epidermis of herbaceous stem
(c) Prickles (d) Spines and leaves.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 119
Ans : SQP 2014 Ans : SQP 2002

Transpiration is the evaporation of water at the Transpiration is the process of water movement
surfaces of the spongy mesophyll cells in leaves, through a plant and its evaporation from aerial
followed by loss of water vapour through the parts, such as leaves, stems and flowers.
stomata. Thus (d) is correct option.
Thus (c) is correct option.
20. Given below is an example of a certain structure
16. The rate of transpiration is more when: and its special functional activity. Which one of
(a) Atmosphere is dry the following pair is incorrect?
(b) Temperature is high (a) Hydathodes ; Guttation
(c) Atmosphere is dry and temperature is high (b) Stomata : Diffusion of gases
(d) Humidity is high (c) Leaf spines : Prevents transpiration by
Ans : MAIN 2018 reducing leaf lamina
(d) Lenticels : Diffusion of gases on the green
As the atmospheric temperature rises, the rate of
stem
transpiration also rises. With high temperature
the water evaporates from the leaf surface quite Ans : SQP 2016
rapidly. In dry and hot air the rate of transpiration
Lenticels are porous tissue consisting of cells
rises further.
with large intercellular spaces in the periderm
Thus (b) is correct option.
of the secondarily thickened organs and the bark
17. Forests contribute in bringing rain by of woody stems and roots of dicotyledonous
(a) bleeding flowering plants.
(b) transpiration Thus (d) is correct option.
(c) guttation
21. Lenticels allow diffusion of gases for ..............
(d) all of them
(a) Respiration
Ans : COMP 2013 (b) Transpiration
Trees release water vapour into the air in a process (c) Photosynthesis
called transpiration. They release extra water in (d) Both (a) and (c)
the form of water vapour from small holes of their
Ans : MAIN 2020
leaves known as stomata ,that water vapour rises
in the atmosphere and form new rain clouds and Lenticels facilitate the gas exchange of oxygen,
that water vapour returns to earth in form of rain. carbon dioxide, and water vapour in plant bodies
Thus (b) is correct option. that produce secondary growth. Thus, it help
in exchange of gases, both in respiration and
18. Lenticels are present on: photosynthesis.
(a) Green stem (b) Woody stem Thus (d) is correct option.
(c) Leaves (d) Flowers
22. Given below are the advantages of transpiration,
Ans : MAIN 2004
except for ..............
Lenticels are raised pores in the stem of a woody (a) Cooling
plant that allows gas exchange between the (b) Suction force
atmosphere and the internal tissues. (c) Distributing water
Thus (b) is correct option. (d) Provides oxygen
19. What is a description of transpiration? Ans : SQP 2021

(a) Exchange of gases between the leaf and the The process of transpiration helps in the exchange
atmosphere. of gases; helps in sending out excessively absorbed
(b) Loss of water vapour from the leaves and water by plants; helps in the absorption and
stems of a plant. distribution of water in plants; and provides
(c) Movement of water from the roots to the coolness to the plant body. It does not provide
leaves. oxygen.
(d) Movement of water through the cells of the Thus (d) is correct option.
leaf.
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CH 4 : TRANSPIRATION

reduces due to cuticles. 11. On a dry, sunny day, how does water vapour move
Thus (b) is correct option. through the stomata of a leaf?
(a) Into the leaf by diffusion
7. Loss of water as droplets from hydathodes is (b) Into the leaf by respiration
called (c) Out of the leaf by diffusion
(a) Transpiration (b) Bleeding (d) Out of the leaf by respiration
(c) Guttation (d) Evaporation
Ans : MAIN 2015
Ans : MAIN 2010
Majority of the absorbed water is lost in form of
Loss of water as droplets from hydathodes is vapour through the stomata of the leaf of plants.
called guttation. This process is called transpiration in plants.
Thus (c) is correct option. Thus (c) is correct option.
8. Which one of the following does not affect the 12. .............. is the change observed in the indicator-
rate of transpiration? dry cobalt chloride in the experimental set up
(a) Light after keeping it in the sunlight.
(b) Humidity (a) No change (b) Red to Blue
(c) Wind (c) Blue to Pink (d) Pink to Blue
(d) Age of the plant
Ans : MAIN 2023
Ans : SQP 2019
Dry cobalt chloride paper that is blue in colour
The rate of transpiration is affected by several turns pink when it comes in contact with water.
factors temperature, humidity, wind speed and Thus (b) is correct option.
light intensity. Some internal factors also affect
rate of transpiration e.g., leaf area, leaf structure 13. Transpiration pull will be maximum under which
and age of plants. Age of the plant is not a factor condition?
that affect transpiration. (a) Open stomata, dry atmosphere and moist
Thus (b) is correct option. soil.
(b) Open stomata, dry atmosphere and dry soil.
9. Which of the following is not true for transpiration? (c) Open stomata, high humidity and moist soil.
(a) It cools the plant (d) Open stomata, high humidity and less
(b) Water lost has minerals temperature.
(c) Water is lost as vapours
(d) Maximum through stomata Ans : MAIN 2011

Ans : MAIN 2009

Transpiration pull will be maximum under open
stomata, dry atmosphere and moist soil.
Mineral salts remain dissolved in the soil water Thus (a) is correct option.
and are absorbed by the roots. Minerals that are
absorbed and accumulated in the xylem duct of 14. Most transpiration in herbaceous plant occurs
the root move up and are distributed in the plant through:
by the transpiration stream. It is not excreted (a) Stomata (b) Lenticels
during transpiration as in transpiration water loss (c) Cuticle (d) Hydathodes
happens in the form of vapour from the green
Ans : COMP 2013
plants.
Thus (b) is correct option. The loss of water through stomata (called
stomatal transpiration) is the most common type
10. With increase in atmospheric pressure, the rate of of transpiration from plants.
transpiration will. Thus (a) is correct option.
(a) increase
(b) decrease 15. From wfuch part of a leaf does most water
(c) remain steady evaporate during transpiration?
(d) slowly increase (a) The cuticle
(b) The guard cells
Ans : SQP 2005
(c) The spongy mesophyll cells
Thus (b) is correct option. (d) The xylem vessels
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 121

31. Desert plants tend to have .............. 35. The water vapour diffuses through the air space
(a) Thick cuticle (b) Thin cuticle between the mesophyll cells into the ..............
(c) No cuticle (d) More stomata (a) Intercellular space
(b) Stomata
Ans : SQP 2013
(c) Sub-stomatal space
Desert plants have a waxy cuticle layer on their (d) Epidermis
leaves. This is an adaptation that helps keep
water in the plant and reduce transpiration. Ans : MAIN 2018

Thus (a) is correct option. In plants, the transpiration stream is the

uninterrupted stream of water and solutes which
32. In a leaf, the cell sap in each cell exerts a .............. is taken up by the roots and transported via the
outward on the cell wall. xylem to the leaves where it evaporates into the
(a) Wall pressure sub-stomatal cavity. After this, the water leaves
(b) Turgor Pressure the leaf by diffusion through stomata.
(c) Osmotic Pressure Thus (c) is correct option.
(d) Both (a) and (b)
36. The .............. generated by a plant assists in
Ans : COMP 2023
bleeding.
The cell wall surrounds the plasma membrane (a) Turgor Pressure
of plant cells and provides tensile strength and (b) Suction force
protection against mechanical and osmotic stress. (c) Root Pressure
It also allows cells to develop turgor pressure, (d) Capillarity
which is the pressure of the cell sap against the
cell wall. Ans : SQP 2019

Thus (b) is correct option. The root pressure generated by a plant forces
the cell sap to rise through the stem. This causes
33. .............. takes place directly from the surface of bleeding or oozing of the cell sap from the cut
the leaves and stems. surface of the plant.
(a) Transpiration Thus (c) is correct option.
(b) Lenticular Transpiration
(c) Stomata transpiration 37. The adaptation of in Nerium to reduce
(d) Cuticular Transpiration transpiration ..............
(a) Sunken stomata
Ans : SQP 2004
(b) Stomata covered by hairs
When loss of water occurs from the surface of (c) Folding of leaves
leaves and herbaceous stem by direct evaporation (d) both (a) and (b)
from the epidermal cells through the cuticle, the
process is cuticular transpiration. Ans : COMP 2003

Thus (d) is correct option. Sunken stomata are present sunken in the leaf
surface and usually surrounded by cuticles and
34. If a plant is kept covered with a polythene sheet hairs often referred to as trichomes in xerophytes
we notice some water drops on the inner side of like Nerium. It is an adaptive feature.
the sheet after sometime. This is due to .............. Thus (c) is correct option.
(a) Evaporation (b) Transpiration
(c) Translation (d) Transportation 38. Each one of the following indicates a method used
to measure the rate of transpiration except for
Ans : MAIN 2017
..............
As the potted plant covered with polythene bag is (a) Weighing method
kept in the sunlight there will be the loss of water (b) Potometer
through the stomata present on the leaves. The (c) Bell-jar experiment
water drops will appear inside the polythene bag (d) Both (a) and (b)
as a result of a loss of water from the stomata.
This is due to transpiration. Ans : SQP 2010

Thus (b) is correct option. A bell-jar experiment gives a visual proof of

transpiration, it does not measure the rate of
CH 4 : TRANSPIRATION

66. A plant physiologist notices droplets of water at (a) A decrease in available water
the tips of leaves in the early morning, a process (b) A decrease in light intensity
known as guttation. Through which special pores (c) A decrease in wind speed
does this process occur?. (d) An increase in humidity
(a) Hydathodes
Ans : SQP 2023
(b) Lenticels
(c) Stomata Too little water available to the plant combined
(d) Cuticle with the usual transpiration will eventually cause
the plant to wilt.
Ans : SQP 2006
Thus (a) is correct option.
Hydathodes are special pores present on the ends
of leaf veins through which guttation occurs and 69. The diagram below shows part of a section
water droplets are given out. through a leaf during day time.
Thus (a) is correct option.

67. The diagram shows a potted plant and the same

plant 24 hours later.

What substance follows the path of the arrow out

What causes the change in the appearance of the of the leaf?
plant? (a) Carbon dioxide (b) Energy
(a) Water loss is greater than water uptake (c) Oxygen (d) Water
(b) Water moves from the leaves to the stem
(c) Water uptake is equal to water loss Ans : MAIN 2017

(d) Water uptake is greater than water loss Water, after absorption by the roots from the
soil, rises up through the xylem in the stem and
Ans : COMP 2020
reaches the spongy mesophyll cells in the leaves.
The wilting condition is found when plant tissues The water then evaporates and saturates the air
contain insufficient water to hold the cells rigid. in the intercellular spaces which then diffuses to
This may occur when the rate of transpiration the outside though the stomata.
exceeds the rate at which water is’ able to enter Thus (d) is correct option.
the root system from a soil containing ample
water or due to a deficiency of water in the soil. 70. A student is investigating the effect of temperature
Thus (a) is correct option. on the rate of transpiration. Which environmental
conditions should be kept constant during this
68. The diagram shows a plant shoot and the same investigation?
shoot five hours later.
Wind Light Humi- Ternpe-
Spesd intensity dity rature
(a) { { { {
(b) { { { ×
(c) { { × ×
(d) × × × {

Which change in environmental conditions could Ans : COMP 2010

cause this change in the shoot?
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 123
Ans : SQP 2021
51. Bleeding
Hydathodes are the special pores in leaves (a) It is a natural process that takes place through
through which guttation occurs. They are present cut/ ruptured surface of the plant.
below the guard cells as hydathodal space and are (b) Loss of water from the uninjured part or
located in margin and tip of leaves in pant and leaves of the plant in the form of water.
grasses. (c) Natural process that takes place through the
Thus (a) is correct option. margins of the plant surface.
(d) The diffusion of water vapour from the surface
48. Guard cells of the cell into the outside atmosphere.
(a) Regulate the closing of stomata
Ans : MAIN 2013
(b) Regulate the opening and closing of stomata
(c) Regulate the opening of stomata The exudation of liquid from the cut or injured
surface of plants, such as date palm and Palmyra
(d) Regulate the process of photosynthesis
palm is known as bleeding. The root pressure
Ans : MAIN 2008 generated by a plant forces the cell sap to rise
Guard cells are cells surrounding each stoma. through the stem. This causes bleeding or oozing
They help to regulate the rate of transpiration by of the cell sap from the cut surface of the plant.
opening and closing the stomata. Thus (a) is correct option.
Thus (b) is correct option. 52. Guttation
49. Stomata: (a) The loss of water in the form of water droplets
(a) Stomata help in diffusion of gases in the from the surface of the leaf.
leaves and in transpiration. (b) The loss of water in the form of water droplets
through the stomata.
(b) Reduce the amount of water lost during
transpiration (c) The loss of water in the form of water vapour
along the leaf margin.
(c) Regulate the opening and closing of guard
(d) The loss of water in the form of water droplets
cells
along the leaf margin.
(d) Reduce the intensity of incident light.
Ans : SQP 2007
Ans : COMP 2002
Guttation is the exudation of drops of xylem sap
Their main function is to allow gases such as
on the tips or edges of leaves of some vascular
carbon dioxide, water vapor and oxygen to move
plants, such as grasses. Water exudes through
rapidly into and out of the leaf.
specialised pores at the tips and the vein endings
Thus (a) is correct option.
(margins) of the leaves called hydathodes.
50. Leaf spines Thus (d) is correct option.
(a) Prevents loss of water from the leaves due to
53. Transpiration.
evaporation.
(a) It is the loss of water as water vapour from the
(b) Reduce the surface area so that the loss of
aerial parts/stems and leaves of the plants.
water due to transpiration is reduced.
(b) The process of removal of water as water
(c) Causes the leaf to roll and prevent evaporation
droplets from the aerial parts/leaf/stomata of
of water.
a plant.
(d) Allow for exchange of respiratory gases and
(c) Exudation of sap from injured parts of a
prevent from browsing animals.
plant.
Ans : SQP 2001 (d) The loss of water in the form of water vapour
In certain plants such as cacti, entire or the from the surface of the leaf only.
parts of the leaves are modified into sharp and Ans : MAIN 2011
pointed structure called as leaf spines. It can act
as defensive structure since it can protect the Transpiration is the biological process by which
plants against grazing animals. It also reduces water is lost in the form of water vapour from the
transpiration. aerial parts of the plants.
Thus (b) is correct option. Thus (a) is correct option.
CH 4 : TRANSPIRATION

23. Transpiration decreases with increase in .............. 27. If the water content of the leaves decreases the
(a) Temperature rate of transpiration ..............
(b) Wind velocity (a) Increases
(c) Atmospheric pressure (b) Depends on other sector
(d) All of the above (c) Remains same
(d) Decreases
Ans : MAIN 2023

Atmospheric pressure affects transpiration, Ans : COMP 2019

because it has influence on the rate of vaporization. If the water content of the leaves decreases,
When atmospheric pressure is high, the rate of stomata will close because there will not be
transpiration is low. enough water to create pressure in the guard
Thus (c) is correct option. cells for stomatal opening. Due to this the rate
of transpiration decreases and this response helps
24. With respect to the Ganong’s potometer, .............. the plant to conserve water.
is incorrect. Thus (d) is correct option.
(a) Coloured water is used
(b) Air bubble is introduced 28. The .............. serves to prevent evaporation of
(c) Reading on the capillary tube indicates the water from the leaf surfaces.
volume of water lost. (a) Lenticels (b) Stomata
(d) None of the above (c) Cuticle (d) both (b) and (c)
Ans : SQP 2002 Ans : SQP 2011

As the transpiration proceeds, i.e., as the water is A waxy layer known as the cuticle covers the
lost from the twig, a suction force is set up which leaves of all plant species. The cuticle reduces the
pulls the water from the beaker and the bubble in rate of water loss from the leaf surface thereby
the capillary tube moves along. The readings on preventing the evaporation of water from the leaf
the capillary tube would give the volume of water surfaces.
lost in a given time. Thus (c) is correct option.
Thus (c) is correct option.
29. More transpiration occurs from the .............. of
25. In a weighing experiment using a test-tube, we a leaf.
will .............. to prevent evaporation. (a) Dorsal surface (b) Under surface
(a) Cover test tube with paper (c) Upper surface (d) both (a) and (b)
(b) Pouring oil on the surface
Ans : SQP 2013
(c) Cover it with polythene bag
(d) Keep it in air- tight container In all green plants transpiration occurs mostly
through the stomata of the leaves. In dicot plants
Ans : COMP 2000
leaves will have more stomata on the lower surface
In a weighing experiment using a test-tube, than the upper surface. So more transpiration
pouring oil on the surface will prevent evaporation. occurs through the lower surface of the leaves of
Thus (b) is correct option. this plant.
Thus (b) is correct option.
26. .............. is observed in most evergreen trees.
(a) Sunken stomata 30. Transpiration is the evaporative loss of water
(b) Leaves covered by thick cuticle from ..............
(c) Rolled leaves (a) Roots
(d) Spines (b) Leaves
(c) Stem
Ans : MAIN 2010
(d) Both (b) and (c)
One of the most important adaptations of
Ans : MAIN 2011
evergreen trees is the thick waxy cuticle that
waterproof the leaves. The thick cuticle layer on Transpiration is the process of release of water
the leaf surface slows the rate of transpiration. vapour from aerial parts, such as leaves, stems
Thus (b) is correct option. and flowers.
Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 125

59. A farmer notices that the rate of transpiration (a) hot, dry and windy
in plants is increasing on certain days, even (b) hot, humid and cool wind
when other factors remain constant. Which (c) humid and windy
environmental factor's decrease is likely causing (d) hot, humid and no wind
this rise in transpiration?
Ans : SQP 2009
(a) Humidity
(b) Light intensity Transpiration will be fastest when the day is hot,
(c) Stomatal opening dry and windy.
(d) Temperature Thus (a) is correct option.

Ans : COMP 2019 63. A botanist is studying how different seasons

When the light intensity is reduced the stomata affect water loss in plants. During which season is
are partially closed and the transpiration is transpiration likely to be the highest?
reduced. (a) Rainy season (b) Winter
Thus (a) is correct option. (c) Summer (d) Autumn
Ans : MAIN 2003
60. A botanist is conducting an experiment to
measure the factors influencing transpiration in Rate of transpiration is decided by the vapour
plants. Which of the following factors is least pressure gradient between internal environment of
likely to affect the rate of transpiration? leaf and atmosphere. Thus, rate of transpiration
(a) Humidity of the atmosphere will be more during summers when atmospheric
(b) Number of open stomata humidity is the least.
Thus (c) is correct option.
(c) Rate of respiration
(d) Temperature 64. During an experiment, a student observes that
Ans : COMP 2020
certain cells play a key role in regulating the
opening and closing of stomata. Which cells are
The rate of transpiration is affected by several primarily responsible for this process?
factors temperature, humidity, wind speed and (a) Epidermal cells
light intensity. Some internal factors also affect (b) Mesophyll cells
rate of transpiration e.g., leaf area, leaf structure (c) Guard cells
and age of plants. Rate of respiration will not (d) Both (a) and (b)
affect the rate of transpiration.
Thus (c) is correct option. Ans : SQP 2003

The opening and closing of stomata is controlled

61. A gardener observes that the plants lose water by the guard cells. When water flows into the
faster on windy days compared to calm ones. guard cells, they swell up and the curved surface
Which factor is most likely responsible for the causes the stomata to open. When the guard cells
increased rate of transpiration? loses water, they shrink and become flaccid and
(a) Increase in humidity straight thus closing the stomata.
(b) Increase in wind velocity Thus (c) is correct option.
(c) Reduced light intensity
(d) Increase in the CO2 level 65. A researcher is investigating various environmental
Ans : MAIN 2016
factors that influence the rate of transpiration in
plants. Which factor is least likely to affect the
At high wind velocity and high temperature, the rate of transpiration?
rate of transpiration is increased but subsequently (a) Intensity of light (b) Velocity of wind
with very high temperature stomata is closed due (c) Carbon dioxide (d) Oxygen
to loss of turgor in guard cells.
Thus (b) is correct option. Ans : SQP 2020

Intensity of light, Temperature, Humidity, Wind

62. A farmer notices that his crops are drying out velocity and Carbon dioxide concentration are the
quickly under certain weather conditions. Under factors that affect transpiration.
which type of weather would the transpiration Thus (d) is correct option.
rate be the fastest?
CH 4 : TRANSPIRATION

54. Which graph shows most clearly what will happen What is X?
to the rate of transpiration as humidity increases? (a) Humidity (b) Light intensity
(c) Soil moisture (d) Temperature
Ans : SQP 2002

Increased humidity has a reduced transpiration.

If there is greater humidity, the surfaces of plants
lose less water by evaporation, which lowers the
demand for water from the roots.
Thus (a) is correct option.

56. A plant shoot is placed in a solution of a dye. The

dye moves up the stem. Under which conditions
will the dye move slowest?

Temperature Humidity
(a) high high
(b) high low
(c) low low
(d) low high

Ans : MAIN 2018

Increased humidity and low temperature reduces

the rate of transpiration.
Thus (d) is correct option.

57. During an experiment, a student notices certain

cells regulating gas exchange on the leaf surface.
Mention the exact location of Guard Cells :
(a) Around the root hairs.
(b) Around the lenticels.
(c) Around the thylakoids.
(d) Around the stoma.
Ans : SQP 2006
Ans : SQP 2021
Transpiration is reduced if the air outside is
humid. High humidity in the air reduces the rate Guard cells are surrounded by stomatal pores and
of outward diffusion of the internal water vapour are located in leaf epidermis.
across stomata, thereby reducing the rate of Thus (d) is correct option.
transpiration.
58. A researcher is studying water loss in different
Thus (b) is correct option.
parts of a plant and observes that the majority
55. The graph shows how the rate of transpiration is of water loss occurs through tiny pores on the
affected by X. leaf surface. Which structure is responsible for
maximum transpiration?
(a) Lenticle
(b) Stomata
(c) Cuticle
(d) Root surface
Ans : COMP 2002

Maximum transpiration occurs through stomata.

Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 127

The rate of transpiration is affected by several are measured again after two hours. What is the
factors, including : temperature, humidity, wind result?
speed and light intensity. To investigate the effect (a) The mass of both plants decreases by the
of temperature on the rate of transpiration, other same percentage.
factors such as temperature, humidity, wind speed (b) The mass of both plants stays the same.
and light intensity should be kept constant. (c) The mass of plant 1 decreases more than the
Thus (b) is correct option. mass of plant 2.
(d) The mass of plant 2 decreases more than the
71. A piece of blue cobalt chloride paper is clipped to mass of plant 1.
the lower surface of a fresh leaf and is then covered
with plastic as shown. After a few minutes, part Ans : MAIN 2008

of the paper turns pink, showing that water is The loss in weight by the plant during the same
present. time will be more in the case of plant 1 due to the
loss of water by transpiration.
Thus (c) is correct option.

73. The diagram shows how water is lost from a leaf.

Which process carried out by leaves causes the

paper to turn pink?
(a) Absorption (b) Photosynthesis By which process is the water lost?
(c) Respiration (d) Transpiration (a) Osmosis (b) Photosynthesis
(c) Translocation (d) Transpiration
Ans : MAIN 2001
Ans : SQP 2004
Cobalt chloride paper is an indicator of moisture.
It is blue when dry and pink when exposed to Transpiration is the process of water movement
moisture. The initial blue cobalt chloride paper through a plant and its evaporation from aerial
will turn pink only in the case of transpiration in parts, such as leaves, stems and flowers.
which water vapour is released. Thus (d) is correct option.
Thus (d) is correct option.
DIRECTION : Matching Type Question
72. The diagram shows an experiment to investigate
transpiration.
74. Priya is studying factors affecting transpiration.
She matched the following factors with their
effects on the rate of transpiration:

Factor Effect on Transpiration

P Increases transpiration when wind
speed increases
Q Decreases transpiration when humidity
is high
Identify the correct pair of factors:
(a) P – Light intensity, Q – Temperature
Plant 1 is not covered. Plant 2 and its pot are (b) P – Wind, Q – Humidity
covered by a transparent plastic bag. The mass (c) P – Humidity, Q – Carbon dioxide
of each plant and its pot is measured. The masses (d) P – Wind, Q – Carbon dioxide
CH 4 : TRANSPIRATION
Ans : Ans :
Wind increases the rate of transpiration by A larger leaf surface area exposes more stomata
removing the water vapor around the leaf surface, to the air, leading to higher water loss through
enhancing water loss. On the other hand, high transpiration. A thick cuticle, which is part of
humidity reduces the rate of transpiration because the leaf structure, serves as a protective barrier
the air is already saturated with moisture, making and reduces water loss, thereby lowering the
it harder for water to evaporate from the leaves. transpiration rate.
Thus (b) is correct option. Thus (b) is correct option.

75. Priya learned about different theories explaining 77. Priya tried to match the advantages of
stomatal movement. She summarized the transpiration with their effects on the plant. She
following: tabulated the following:

Theory Explanation Advantage Effect on the plant

P Starch is converted to sugar in light to P Maintains turgidity of plant cells
open stomata
Q Promotes the uptake and
Q Potassium ion accumulation causes translocation of solutes
stomata to open in light
Identify the correct pair of advantages:
Identify the correct pair of theories:
(a) P – Cooling effect, Q – Absorption of water
(a) P – Active potassium ion transport, Q –
Starch-sugar interconversion (b) P – Hardening, Q – Improvement of fruit
(b) P – Starch-sugar interconversion, Q – Active quality
potassium ion transport (c) P – Maintenance of turgidity, Q – Promotion
(c) P – Cuticular transpiration, Q – Lenticular of solute uptake
transpiration (d) P – Leaf abscission, Q – Wilting injury
(d) P – Guard cell transport theory, Q – Water
absorption theory Ans :
Transpiration helps in maintaining the turgidity
Ans :
of cells, which is important for structural
The starch-sugar interconversion theory explains support in plants. It also promotes the uptake
that stomata open in light due to the enzymatic and translocation of essential solutes from the
conversion of starch into sugar, increasing osmotic soil to different parts of the plant through the
concentration and water absorption. The active transpiration stream.
potassium ion transport theory states that Thus (c) is correct option.
potassium ions accumulate in guard cells in light,
decreasing their osmotic potential and causing 78. Priya is studying guttation in plants. She matched
the stomata to open. the plant examples with the process of guttation
Thus (b) is correct option. as follows:

76. Priya matched the factors affecting the internal Plant Process observed
control of transpiration in plants. She tabulated
P Water droplets exude from the tips of
the following:
leaves through hydathodes
Factor Effect on Transpiration Q Exudation of sap from injured parts of
P Larger leaf surface area increases plants
transpiration Identify the correct pair of plants:
Q Thick cuticle reduces transpiration (a) P – Chrysanthemum, Q – Euphorbia
Identify the correct pair of factors: (b) P – Garden nasturtium, Q – Colocasia
(a) P – Leaf structure, Q – Leaf area (c) P – Potato, Q – Tomato
(b) P – Leaf area, Q – Leaf structure (d) P – Sunflower, Q – Balsam
(c) P – Root shoot ratio, Q – Atmospheric humidity
(d) P – Temperature, Q – Light intensity Ans :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 129

Guttation is the process where water droplets are Increase in temperature, decrease in humidity,
exuded from the tips of leaves through specialized strong wind, and sunlight all increase the rate
pores called hydathodes, as seen in plants like of transpiration. However, high atmospheric
Chrysanthemum. Bleeding is the exudation of sap pressure reduces the transpiration rate, and high
from injured plant parts, and this can be observed humidity reduces water loss.
in Euphorbia, where latex or sap flows due to root Thus (a) is correct option.
pressure.
Thus (a) is correct option. 81. A biology teacher asked her students to identify
the two major types of transpiration in plants.
Raj said: Lenticular transpiration and Cuticular
DIRECTION : Conversation Based Question transpiration.
Sonu said: Stomatal transpiration and Cuticular
79. A biology teacher asked her students to explain transpiration.
what regulates the opening and closing of stomata Lata said: Stomatal transpiration and Guttation.
in plants. Abhay said: Lenticular transpiration and Stomatal
Raj said: Guard cells regulate stomatal opening transpiration.
by controlling water movement. Who gave the correct response?
Sonu said: Epidermal cells control the stomata (a) Sonu and Abhay
directly. (b) Raj and Lata
Lata said: Guard cells regulate the opening and (c) Sonu and Lata
closing based on light. (d) Sonu and Abhay
Abhay said: Guard cells use potassium ions to
regulate stomatal movement. Ans :
Who gave the correct explanation? The two major types of transpiration in plants are
(a) Raj and Lata stomatal transpiration (which accounts for most
(b) Sonu and Lata water loss) and lenticular transpiration. Cuticular
(c) Raj and Abhay transpiration also occurs, but guttation is not
(d) Abhay and Lata considered transpiration.
Thus (d) is correct option.
Ans :
The guard cells regulate the opening and closing 82. A biology teacher asked her students to explain the
of stomata by controlling water movement and difference between transpiration and guttation.
potassium ions. This process is influenced by Raj said: Transpiration is the loss of water as
environmental factors such as light, but epidermal vapor, while guttation is the loss of liquid water.
cells are not directly responsible for this regulation. Sonu said: Both transpiration and guttation occur
Thus (c) is correct option. during the night.
Lata said: Guttation occurs through lenticels,
80. A teacher asked her students to list factors while transpiration occurs through stomata.
affecting the rate of transpiration in plants. Abhay said: Transpiration and guttation both
Raj said: Increase in temperature and decrease in help cool the plant.
humidity increases transpiration. Who provided the correct explanation?
Sonu said: High atmospheric pressure increases (a) Raj and Lata
transpiration. (b) Raj and Abhay
Lata said: Strong wind and sunlight increase the (c) Sonu and Lata
rate of transpiration. (d) Raj and Sonu
Abhay said: Increase in humidity increases
transpiration. Ans :
Who gave the correct explanations? Transpiration involves the loss of water vapor
(a) Raj and Lata through stomata, while guttation involves the loss
(b) Sonu and Abhay of liquid water through hydathodes. Both processes
(c) Lata and Abhay can help cool the plant, but transpiration occurs
(d) Raj and Abhay during the day, and guttation often happens at
night due to root pressure.
Ans :
Thus (b) is correct option.
CH 4 : TRANSPIRATION

(a) If both assertion and reason are true and cells that surround the stoma.
reason is the correct explanation of assertion. Thus (c) is correct option.
(b) If both assertion and reason are true, but
reason is not the correct explanation of 95. Match the items of Column A with those in
assertion. Column B and select the correct option :
(c) If assertion is true but reason is false. Column I Column II
(d) If both assertion and reason are false.
(A) Cactus (i) Exudation of sap
Ans : MAIN 2013
from injured part
Lenticels are porous tissue consisting of cells (B) Banana leaf (ii) Special pores at the
with large intercellular spaces in the periderm tip of veins
of the secondarily thickened organs and the bark
of woody stems and roots of dicots. It functions (C) Hydathodes (iii) Water droplets
as a pore, providing a pathway for the direct along the margin of
exchange of gases between the internal tissues and the leaf only in the
atmosphere through the bark, which is otherwise morning.
impermeable to gases. The loss of water from (D) Bleeding (iv) Leaf spines
lenticels is very insignificant as it amounts to only (a) (A) - (iv), (B) - (iii), (C) - (ii), (D) - (i)
0.1% of the total. (b) (A) - (iv), (B) - (ii), (C) - (iii), (D) - (i)
Thus (c) is correct option. (c) (A) - (iv), (B) - (iii), (C) - (i), (D) - (ii)
(d) (A) - (iv), (B) - (i), (C) - (iii), (D) - (ii)
DIRECTION : Match the following : Ans : MAIN 2010

94. Match the items of Column A with those in Cactus have leaf spines which protect the plant
Column B and select the correct option: from predators, provide shade, help regulate
temperature, reduce water loss and even help the
Column I Column II plant to spread and reproduce. Droplets of water
may sometimes be seen along the margins of the
(A) Lenticels (i) An indicator of
leaves of a banana plant, growing in wet soil only
moisture
in the mornings. Hydathodes are specialized pores
(B) Cobalt chloride (ii) Sunken stomata (openings) particularly present at the tip of veins
paper on the leaf margins. The exudation of cell sap
(C) Nerium (iii) Minute openings from an injured part of a plant is called bleeding.
on the woody Thus (a) is correct option.
stems
(D) Guard cells (iv) Kidney shaped
cells that surround
the stoma ONE MARK QUESTIONS
(a) (A) - (ii), (B) - (i), (C) - (iii) , (D) - (iv)
(b) (A) - (iii), (B) - (ii), (C) - (i) , (D) - (iv) DIRECTION : Name the following :
(c) (A) - (ii), (B) - (iii), (C) - (ii) , (D) - (iv)
(d) (A) - (i), (B) - (iii), (C) - (ii) , (D) - (iv) 96. The openings on the barks of trees through which
Ans : SQP 2004 transpiration
Lenticels are the minute openings on the stem of Ans : SQP 2025
a woody plant that allows gas exchange between Potometer
the atmosphere and the internal tissues. Cobalt
chloride paper is used as an indicator of moisture. 97. Name the structures through which Transpiration
Nerium is a xerophyte, it has sunken stomata to and Guttation occur in a plant.
curtail the water loss by transpiration. Guard
Ans : SQP 2025
cells are specialized plant cells in the epidermis
of leaves, stems and other organs that are used Transpiration — Stomata, Lenticels, Cuticle
to control gas exchange. They are kidney shaped Guttation — Hydathodes
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 131

(a) If both assertion and reason are true and Transpiration is essential for the movement of
reason is the correct explanation of assertion. water and minerals from the root to the healthy
(b) If both assertion and reason are true, but parts of the plant. But excess transpiration may
reason is not the correct explanation of result in drying up of the leaves or wilting and loss
assertion. of soil water. Hence, it is termed as a necessary
(c) If assertion is true but reason is false. evil.
(d) If both assertion and reason are false. Thus (a) is correct option.
Ans : COMP 2002
91. Assertion: Stomata remain open during the day
Light has indirect effect on the rate of time.
transpiration. It affects the rate in two ways: firstly Reason: Stomata helps in exchange of gases.
by controlling the stomatal opening and secondly (a) If both assertion and reason are true and
by affecting the temperature. With the increase reason is the correct explanation of assertion.
in the light intensity the rate of transpiration (b) If both assertion and reason are true, but
increases because the stomata get opened and the reason is not the correct explanation of
temperature increases. The rate of transpiration assertion.
increases markedly in light and decreases in dark. (c) If assertion is true but reason is false.
There is a close relationship between the opening (d) If both assertion and reason are false.
of stomata and presence of light.
Thus (a) is correct option. Ans : MAIN 2007

Stomata are open during the day because this is

89. Assertion: Deciduous trees have to shed their
when photosynthesis typically occurs. Opening
leaves during autumn.
and closing of stomata occur due to turgor changes
Reason: This is an adaptation to check loss of
in guard cells. Stomata are chiefly concerned with
water by transpiration.
gaseous exchange during photosynthesis and
(a) If both assertion and reason are true and
respiration and water loss through transpiration.
reason is the correct explanation of assertion.
Thus (b) is correct option.
(b) If both assertion and reason are true, but
reason is not the correct explanation of 92. Assertion: The potometer does not measure the
assertion. transpiration rate accurately.
(c) If assertion is true but reason is false. Reason: Potometer usually measures the rate of
(d) If both assertion and reason are false. water uptake.
Ans : MAIN 2000 (a) If both assertion and reason are true and
reason is the correct explanation of assertion.
Most deciduous trees lose their leaves to avoid
(b) If both assertion and reason are true, but
excessive loss of water through transpiration. The
reason is not the correct explanation of
new leaves are formed during the next suitable
assertion.
growing season. Trees shed their leaves in the dry
(c) If assertion is true but reason is false.
season to conserve water for transpiration because
(d) If both assertion and reason are false.
in dry season there is scarcity of water.
Thus (a) is correct option. Ans : SQP 2011

The potometer does not measure the transpiration

90. Assertion: Transpiration is a necessary evil.
rate accurately because not all the water taken up
Reason: It causes water loss but helps in absorption
by the plant is used for transpiration. A potometer
and upward movement of water and minerals.
can be used to measure the rate of transpiration
(a) If both assertion and reason are true and
that’s proportional to water uptake.
reason is the correct explanation of assertion.
Thus (b) is correct option.
(b) If both assertion and reason are true, but
reason is not the correct explanation of 93. Assertion: Lenticels functions as a pore, providing
assertion. a pathway for the direct exchange of gases between
(c) If assertion is true but reason is false. the internal tissues and atmosphere through the
(d) If both assertion and reason are false. bark.
Reason: Lenticular transpiration amounts to 10%
Ans : SQP 2019
of the total transpiration.
CH 4 : TRANSPIRATION

191. Stomata are located more on the ventral side of (c) Contain guard (c) Guard cells are
a leaf. cells. absent
Ans : SQP 2005
196. Transpiration and Guttation.
The rays of sunlight on dorsal surface of the
leaves will cause greater loss of water through Ans : MAIN 2013

the stomatal opening. To reduce transpiration,

stomata are located on the ventral surface of a Transpiration Guttation
leaf. (a) Water is lost in (a) Water is lost
the form of water in the form of
DIRECTION : Distinguish between the following vapour. (gaseous droplets. (liquid
pairs : form) form)
(b) Occurs during (b) Occurs during
192. Write down the difference between the following day time. night.
pairs as indicated within the brackets : (c) Occurs mainly (c) Occurs through
Guttation and bleeding in plants (cause) through stomata hydathodes.
Ans : SQP 2011

Guttation : Loss of water in the form of droplets 197. Transpiration and Translocation.
through hydathodes. Ans : COMP 2021
Bleeding : Exudation of sap from the injured part.
Transpiration Translocation
193. Differentiate between :
(i) Transpiration and guttation (form of water) (a) It is the loss (a) It is the
(ii) Lenticels and stomata in old plants (gases of water in the transportation
given out during day time). form of vapour. of food materials
within the plant
Ans : COMP 2012
body.

(i) Transpiration Guttation (b) It occurs (b) It occurs through

In the form of In the form of through stomata. vascular tissues,
water vapours water droplets i.e. xylem and
phloem.
(ii) Lenticels Stomata
Carbon dioxide Oxygen 198. Stomatal transpiration and Cuticular
transpiration.
194. Differentiate between Stoma and stroma
Ans : SQP 2020
Ans : MAIN 2012

Stoma: The small opening between the guard Stomatal Cuticular

cells. Transpiration Transpiration
Stroma is the ground substance of chloroplast. (a) It occurs (a) It occurs through
through stomata. cuticle of the
195. Stomata and Lenticels. leaves.
Ans : SQP 2007
(b) Transpiration (b) Transpiration
is more in the is less in the
Stomata Lenticels
leaves. leaves due to
(a) Minute openings (a) These are found the presence of
present mainly on in the bark of cuticle.
leaves woody stems.
(b) Stomata can be (b) These are always 199. Lenticular Transpiration and Stomatal
opened and closed opened. Transpiration.
Ans : COMP 2011
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 133

98. An apparatus to compare the rate of transpiration 108. The plant having sunken stomata.
in cut shoots.
Ans : MAIN 2010
Ans : SQP 2000
Nerium
Potometer
109. The cells which control opening and closing of
99. Respiratory openings found on the stems of stomata.
woody plants.
Ans : SQP 2018
Ans : MAIN 2000
Guard cells
Lenticels
110. The plant in which stomata are absent.
100. The process by which intact plants lose water in
Ans : MAIN 2021
the form of droplets.
Hydrilla (Submerged aquatic plant)
Ans : COMP 2015, 1999

Guttation 111. The plant having sunken stomata.

Ans : COMP 2013
101. Openings on the stem through which transpiration
occurs. Nerium

Ans : MAIN 2005, 1999 112. The structure through which guttation takes
Lenticels place.
Ans : SQP 2023
102. Openings found on the under surface of
dorsiventral leaves. Hydathodes

Ans : SQP 2020 113. An experiment to demonstrate transpiration.

Stomata Ans : MAIN 2014

103. The paper which is used to show loss of water Bell jar experiment
through stoma of a leaf
114. An apparatus used to compare the rate of
Ans : COMP 2017 transpiration in cut shoot.
Cobalt chloride paper Ans : COMP 2019

104. An instrument used for measuring the rate of Potometer

transpiration.
115. A chemical normally used to test the rate of
Ans : MAIN 2021 transpiration on either side of a leaf.
Potometer Ans : MAIN 2003

105. The loss of water from injured parts of a plant. Cobalt chloride

Ans : SQP 2017 116. The process of loss of water in the form of droplets.
Bleeding Ans : COMP 2019

106. A plant with sunken stomata. Guttation

Ans : MAIN 2010 117. The small pores present on the leaf.
Nerium, Pinus Ans : SQP 2017

107. The wax-like layer on the epidermis of leaves Stomata

which reduces transpiration.
118. The experiment to demonstrate transpiration.
Ans : COMP 2018, 2013
Ans : MAIN 2021
Cuticle
Bell jar experiment
CH 4 : TRANSPIRATION

83. A teacher asked her students to name the apparatus (c) If assertion is true but reason is false.
used to measure the rate of transpiration. (d) If both assertion and reason are false.
Raj said: Potometer.
Ans : SQP 2023
Sonu said: Hygrometer.
Lata said: Anemometer. Reduced surface area reduce the loss of water by
Abhay said: Barometer. transpiration. Hence, both assertion and reason
Who is correct? are true and reason is the correct explanation of
(a) Raj assertion.
(b) Sonu Thus (a) is correct option.
(c) Lata
86. Assertion: In hot summer months most herbaceous
(d) Abhay
plants wilt at noon and recover in the evening.
Ans : Reason: Plant shows wilting due to loss of
The potometer is an apparatus used to measure the turgidity.
rate of water uptake by a plant, which indirectly (a) If both assertion and reason are true and
measures transpiration. Hygrometers measure reason is the correct explanation of assertion.
humidity, anemometers measure wind speed, and (b) If both assertion and reason are true, but
barometers measure atmospheric pressure. reason is not the correct explanation of
Thus (a) is correct option. assertion.
(c) If assertion is true but reason is false.
(d) If both assertion and reason are false.
Ans : MAIN 2015
ASSERTION AND REASON Loss of water from leaves, by transpiration far
exceeds the absorption of water by the roots.
Thus, the plant shows wilting due to loss of
84. Assertion: Transpiration cools the plant.
turgidity.
Reason: Evaporation of water vapours reduces
Thus (a) is correct option.
the temperature of the leaf surface.
(a) If both assertion and reason are true and 87. Assertion: Transpiration occurs through stomata
reason is the correct explanation of assertion. Reason: Guttation is due to root pressure.
(b) If both assertion and reason are true, but (a) If both assertion and reason are true and
reason is not the correct explanation of reason is the correct explanation of assertion.
assertion. (b) If both assertion and reason are true, but
(c) If assertion is true but reason is false. reason is not the correct explanation of
(d) If both assertion and reason are false. assertion.
Ans : COMP 2021 (c) If assertion is true but reason is false.
(d) If both assertion and reason are false.
Evaporation of water vapours reduces the
temperature of the leaf surface as the latent heat Ans : SQP 2001
required to convert water into water vapours is Transpiration is the process of water movement
taken from the plant body, thereby lowering the through a plant and its evaporation from aerial
temperature. Hence, both assertion and reason parts, such as leaves, stems and flowers. It occurs
are true and reason is the correct explanation of mostly at the leaves through the minute openings
assertion. present on the leaves called stomata. Hence,
Thus (a) is correct option. Assertion is correct. At night in some plants, root
pressure causes guttation or exudation of drops of
85. Assertion: Leaves are reduced to spines in cactus.
xylem sap from the tips or edges of leaves. Thus,
Reason: Leaves are modified to form spines to
guttation is due to root pressure.
reduce the leaf lamina.
Thus (b) is correct option.
(a) If both assertion and reason are true and
reason is the correct explanation of assertion. 88. Assertion: Light is one of the important factor in
(b) If both assertion and reason are true, but transpiration.
reason is not the correct explanation of Reason: Transpiration increases in light and
assertion. decreases in dark.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 135

138. Folded leaves______transpiration. 147. Moist cobalt chloride paper is blue in colour.
Ans : MAIN 2008 Ans : MAIN 2022

reduces False, Dry cobalt chloride paper is blue in colour.

139. In Nerium, stomata are______. 148. Lenticular transpiration occurs in herbs.

Ans : COMP 2004 Ans : COMP 2019

sunken False, Lenticular transpiration occurs in old

stems.
DIRECTION : Mention whether the following 149. The upper surface of the leaves transpires more.
statements are True or False. If false, correct and
rewrite by changing the first or last word only: Ans : SQP 2016

False, The upper surface of the leaves transpires

140. Low humidity in the atmosphere results in a less.
decrease in the rate of transpiration.
150. The wall of guard cells towards the stoma is thin.
Ans : SQP 2004, 1996
Ans : MAIN 2010
False.
False, The wall of guard cells towards the stoma
141. The rate of transpiration will be more if the air is thick
is humid.
151. Leaves are reduced to spines in xerophytic plants.
Ans : MAIN 2002, 1995
Ans : SQP 2019
False, The rate of transpiration will be more if
the air is dry. True

142. The pH of the guard cells increases during day 152. Loss of water in form of droplets is called bleeding.
time. Ans : MAIN 2013

Ans : SQP 2013 False, Loss of water in the form of droplets is

True. called guttation.

143. The escape of plant-sap from the cut surface is 153. Stomata covered by hairs decreases transpiration.
called guttation. Ans : SQP 2001

Ans : COMP 2009 True

False, The escape of plant-sap from the cut surface
154. The upper surface of the leaves transpires more.
is called bleeding.
Ans : COMP 2007
144. Lower the atmospheric pressure, higher the rate
False
of transpiration.
Ans : MAIN 2010 155. Transpiration takes place only in green plants.
True, Ans : MAIN 2012

145. Structure of hydathodes and stomata are similar. True

Ans : COMP 2006 156. Lenticular transpiration occurs in herbs.
False, Structure of hydathodes and stomata are Ans : COMP 2018
different.
False
146. Transpiration takes place only in green plants.
157. The pH of guard cells increase during day time.
Ans : SQP 2010
Ans : SQP 2023
True.
True
CH 4 : TRANSPIRATION

119. A chemical normally used to test the rate of 128. The phenomenon of loss of water through a cut
transpiration on either side of a leaf. stem or injured part of plant is called______.
Ans : COMP 2008 Ans : MAIN 2015

Cobalt chloride bleeding

120. The structure through which guttation takes 129. 97% of the total transpiration takes place
place. through______.
Ans : MAIN 2010 Ans : SQP 2023

Hydathode stomata

121. Small openings present on the bark of woody 130. Exchange of gases in plants takes place
stems. through______.
Ans : COMP 2022 Ans : COMP 2015

Lenticels stomata

122. A chemical used to prevent excessive transpiration 131. ______has cooling effects on the leaves.
in plants.
Ans : MAIN 2012
Ans : MAIN 2017
Transpiration
Silicon emulsion/Phenyl Mercuric Acetate (PMA)
132. The leaves of the______plants have cuticular
123. Three different kinds of structures of a plant from wax.
where transpiration occurs.
Ans : SQP 2005
Ans : COMP 2023
xerophytic
(a) Lenticel
(b) Stomata 133. The minute pores on the epidermis of the leaf are
(c) Cuticle known as______.
Ans : MAIN 2003
124. The metallic cation involved in opening and
closing of stomata. stomata

Ans : MAIN 2009 134. ______is an instrument for measuring the rate
Potassium ion. of transpiration.
Ans : COMP 2000
125. The structure through which most of the
transpiration takes place. Potometer

Ans : SQP 2020 135. The chemicals used to reduce the rate of
Stomata transpiration are called______.
Ans : MAIN 2004
126. The process by which the aerial parts of a green
plant give out water as water vapour. anti-transpirants/silicon emulsions.

Ans : MAIN 2013 136. Guttation occurs through______

Transpiration. Ans : COMP 2017

hydathodes
DIRECTION : Complete the following statements:
137. More stomata are located on the______
127. Hydathodes and______. surface.

Ans : SQP 2000

Ans : SQP 2013

Guttation ventral
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 137
Ans : COMP 2013
the exposed surface area for transpiration.
Cuticle
185. Balsam plants wilt during midday even if the soil
177. An apparatus that measures the rate of water is well-watered.
uptake in a cut shoot due to transpiration. Ans : COMP 2014
Ans : MAIN 2017
The rate of transpiration is greater than the rate
Ganong’s potometer of absorption during midday. So, Balsam plants
wilt during midday.
178. Permanently open structures seen on the bark of
an old woody stem. 186. Transpiration cools the plants.
Ans : COMP 2013 Ans : MAIN 2016

Lenticels Transpiration reduces temperature of the leaf

surface.
179. Exudation of sap from injured parts of a plant.
187. Herbaceous plants growing in well-watered soil
Ans : SQP 2015
are found to wilt on a hot day.
Bleeding
Ans : COMP 2012

180. A waxy layer covering the epidermis of leaves. On a hot day, the rate of transpiration is greater
Ans : MAIN 2010 than the rate of absorption of water from the
soil. Therefore, the cells of herbaceous plants lose
Cuticle
turgidity and wilt fast.
181. The kidney-shaped structures present in the
stomata. 188. Xerophytes have their leaves modified to spines or
reduced in size.
Ans : COMP 2021
Ans : SQP 2021
Guard cells
Xerophytes grow in regions where availability of
182. Loss of water from the aerial parts of the plant. water is scarce. In order to reduce transpiration,
their leaves are modified into spines or reduced
Ans : SQP 2023
in size.
Transpiration.
189. Rate of transpiration will be more on a windy day
rather than on a calm day.
DIRECTION : Account for the following or give
scientific reason: Ans : COMP 2011

On a windy day, the water vapour released during

183. In some xerophytes leaves are modified into transpiration is removed faster from the leaves.
spines. The surrounding area becomes unsaturated which
Ans : MAIN 2017
makes water passes out of the plant as water
vapour. This enhances the rate of transpiration.
Modification of leaves into spines is an adaptive
feature of xerophytes. Xerphytes grow in regions 190. In a winter morning, droplets of water may be
where water is scarce. This modification reduces seen along the margin of grass plants leaves.
transpiration.
Ans : MAIN 2002
184. The leaves of certain plants roll up on a bright During winter, the air around the grass plants
sunny day. become humid, which reduces the rate of
Ans : SQP 2010 transpiration. But, as the rate of absorption is
high, this builds up a hydrostatic pressure within
On a bright sunny day, the rate of transpiration
the plants and forces the excess water out from
is more than the rate of absorption of water.
the tip of the vein through hydathodes .This
Leaves contain numerous stomata through which
process is called guttation.
transpiration occurs. Rolling up of leaves reduces
CH 4 : TRANSPIRATION

(iii) Loss of water as droplets from hydathodes is 4. Presence of dense cutinised hairs and scales
called : (Transpiration, Bleeding, Guttation) around stomata.
Ans : MAIN 2010
235. Name the factors which control transpiration.
(i) Open stomata, dry atmosphere and moist Ans : SQP 2003
soil.
(ii) Guttation 1. Sunlight
(iii) Guttation 2. Temperature
3. Humidity of air
231. Draw a neat diagram of the stomatal apparatus 4. Wind velocity
found in the epidermis of leaves and label the 5. Available soil water
stoma, guard cells, chloroplast,epidermal cells,
cell wall and nucleus. 236. Mention three advantages of transpiration.

Ans : COMP 2017 Ans : COMP 2018

A Stomatal apparatus. (i) It provides a suction force.

(ii) It produces a cooling effect.
(iii) It helps in the distribution of water throughout
the plant.

237. Explain the mechanism of stomatal transpiration.

Ans : COMP 2012

From the xylem vessels of the leaf veins, water

vapour diffuse out into the intercellular spaces
of the leaves. When the guard cells draw water
from surrounding cells and becomes turgid, the
inner thick walls are pulled apart resulting in the
opening of the guard cells. Due to this, the gap
232. Mention three adaptations found in plants to
called the stoma opens and water vapour goes out
reduce transpiration.
and thus transpiration takes place.
Ans : MAIN 2009
238. What is Ganong’s Potometer used for? Write any
(i) Thick cuticle
two limitations of this apparatus.
(ii) Narrow leaves
(iii) Sunken stomata Ans : SQP 2003

Ganong’s Potometer is used to measure the rate

233. Blowing wind can be useful to the plants in
of transpiration.
many ways. Mention any three such uses giving a
Limitations are: The introduction of air bubble
suitable example wherever possible.
is not easy, the plant uses some water for
Ans : SQP 2006 photosynthesis, and other metabolic activities
Blowing wind helps in : which cannot be measured.
(i) the dispersal of fruits and seeds of the plants.
239. How does velocity of wind affect the rate of
e.g. Oak.
transpiration?
(ii) cross pollination, e.g. maize.
(iii) increasing transpiration and so absorption of Ans : SQP 2023

water and mineral. HoIf the velocity of wind increase, the rate of
transpiration increases. High velocity of wind
234. What are the anatomical adaptations observed in
removes water vapour from near the surface of
plants which checks transpiration.
leaves and the surrounding area is not saturated
Ans : MAIN 2015 as a result transpiration rate is higher. If wind
1. Stomata in sunken pits velocity is low, the water vapours are not removed
2. Waxy cuticle from near the leave surface and so transpiration
3. Multiple (thick) epidermis is slow.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 139

Lenticular Stomatal 3. Guttation (c) Maize plant

Transpiration Transpiration 4. Low rate of (d) Xylem
(a) It takes place (a) It takes place transpiration
through lenticels. through stomata. 5. High rate of (e) Hydathodes
(b) Does not contain (b) Contains guard transpiration
guard cells to cells to control it.
control it. Ans : MAIN 2014

1 – (b), 2 – (d), 3 – (e), 4 – (a), 5 – (c).

200. Mention one condition in which the stomatal
opening Mention any two differences between :
DIRECTION : Rewrite the terms in logical sequence
(a) Transpiration and Evaporation
as directed at the end of each statement.
(b) Stomata and lenticels.
Ans : SQP 2001 203. Stoma, Mesophyll cells, Xylem, Substomatal
(a) space, Intercellular space. (loss of water due to
transpiration)
Transpiration Evaporation
Ans : SQP 2010
1. It is a physiological 1. It is purely a
Xylem, Mesophyll cell, Intercellular space,
process. physical process.
Substomatal space, Stoma.
2. It usually occurs 2. It occurs all time.
at day time. 204. Endodermis, Cortex, Soil water, Xylem, Root
hair.
(b)
Ans : COMP 2013
Stomata Lenticels
Soil water, root hair, cortex, endodermis, xylem
1. Located on 1. Located on stem
lower surface and branches of
DIRECTION : Answer the following :
of dicot leaves, woody plants.
both surfaces of
monocot leaves. 205. How does Transpiration help in the uptake of
water from the soil?
2. Remain open 2. Remain open
during daytime. every time. Ans : SQP 2025

As water evaporates, a suction force is created

201. Transpiration and Perspiration. which draws water up through the stem.
Ans : SQP 2003 206. Explain the following terms :
(i) Bleeding
Transpiration Perspiration (ii) Transpiration
(a) It takes place in (a) It takes place in Ans : SQP 2006, 2001
plants. animals.
(i) Bleeding – Exudation of sap or watery
(b) It takes place (b) It takes place solution from the cut or injured parts of a
mainly through through sweat plant is called bleeding.
stomata. pores in the skin. (ii) Transpiration is the loss of water in the form
of water vapours from the aerial parts of
202. Match the items given in column I with those of plants.
column II :
207. List any two advantages of transpiration to a
Column I Column II plant.
1. Transpiration (a) Cactus Ans : MAIN 2001

2. Movement of (b) Stomata Ascent of sap, Cooling.

water
CH 4 : TRANSPIRATION

158. Loss of water is called bleeding. In some xerophytes, leaves are modified into
spines.
Ans : MAIN 2020

False Ans : SQP 2017

Since xerophytes grow in dry conditions where

water is less, in order to reduce transpiration their
DIRECTION : Write the exact location of the
leaves are modified into spines.
following:
168. State the main function of the Guard cells.
159. Hydathodes.
Ans : COMP 2000
Ans : COMP 2018, 2011
Help in opening and closing of stomata.
Hydathodes are located along the leaf margins.
169. Stomata
160. Stoma.
Ans : MAIN 2022
Ans : MAIN 2010
Stomata : Transpiration and respiration.
Stoma is located on the epidermis of the leaves.
170. Hydathodes
161. Lenticles.
Ans : SQP 2010
Ans : SQP 2016
Hydathodes : The removal of water drops through
Lenticles are located on the older stems. hydathodes is called guttation.
162. Gurad cells. 171. Guard cells
Ans : COMP 2023 Ans : COMP 2017

Guard cells are located in stomata. Guard cells : Help to open and close stomata.

172. Waxy cuticle

DIRECTION : State the function of the following:
Ans : SQP 2020

163. Lenticles Waxy cuticle helps to reduce transpiration rate.

Ans : MAIN 2014
173. Leaf spines
Lenticle : Exchange of gases in older stems.
Ans : MAIN 2016

164. Sunken stomata Leaf spines help to reduce transpiration.

Ans : SQP 2016

To reduce transpiration. DIRECTION : Give scientific or technical terms for

the following :
165. State the exact location of the Guard cells.
Ans : COMP 2013 174. Loss of water in the form of water droplets from
the margin of leaves.
Epidermis of leaves
Ans : MAIN 2003, 1997
166. Given below are fine groups of terms. In each
Guttation
group arrange and rewrite the terms in the correct
order as to be in Logical Sequence. 175. Transports manufactured food from leaves to
Spongy cells, upper epidermis, stoma, palisade other parts of the plant.
tissue, substomatal space.
Ans : SQP 2002
Ans : MAIN 2013
Phloem.
Upper epidermis, palisade tissue spongy cells,
substomatal space, stoma. 176. The waxy layer on the epidermis of the leaf meant
to reduce transpiration.
167. Give biological reasons for the following statement:
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 141

223. Explain how the rate of transpiration is affected If the rate of transpiration exceeds the rate
on: absorption of water by the roots, leave cells of
(a) a windy day herbaceous plants lose turgidity and the leaves
(b) a foggy day droop. This condition is called wilting.
Ans : MAIN 2020

(a) On a windy day, the water vapour released

from the leaves by transpiration is removed THREE MARKS QUESTIONS
at a faster rate near the ventral leaf surface.
The surrounding air around the leaf does not
get saturated with water. So, transpiration is 229. Sam observed a slide containing the lower
more during windy day. epidermis of a leaf under a microscope. A number
(b) On a foggy day, the area surrounding the plant of tiny openings between the epidermal cells were
leaves are saturated with water. So, water present as shown below in the diagram:
vapour from the leaves is removed very slowly
thereby reducing the rate of transpiration.

224. A well watered potted plant shows wilting of

leaves on hot sunny day. Explain the reason.
Ans : COMP 2011

On a hot sunny day, there occurs greater

transpiration than the water absorbed by the
roots hence it results in wilting of leaves.

225. Briefly explain how the rate of transpiration is

affected by
(i) Intensity of light
(ii) Humidity of the atmosphere
Ans : SQP 2001

(i) More the intensity of light, more is the rate of

transpiration.
(i) What are these tiny openings called?
(ii) Humidity decreases rate of transpiration.
(ii) Name the cells that regulate the opening and
226. Why do plants absorb more water than what is closing of the: structures.
required by them ? (iii) Which ion is responsible for the opening and
closing of the: openings?
Ans : SQP 2017
Ans : SQP 2025
Plants absorb more water than what is required
by them because minerals are present in extremely (i) Stomata
small quantity in absorbed water. Hence, to (ii) Guard cells
obtain a continuous supply of minerals, they have (iii) K+ / Potassium ions
to absorb large quantities of water.
230. Choose the correct alternative :
227. What is wilting ? What are the causes of this (i) Transpiration pull will be maximum under
condition? which of the following conditions : (open
stomata, dry atmosphere and moist soil;
Ans : MAIN 2002 open stomata, high humid atmosphere and
The drooping down of leaves due to loss of water well irrigated soil; open stomata, high humid
is called wilting. It may be caused due to excessive atmosphere and dry soil; closed stomata, dry
transpiration, blocking of xylem elements. atmosphere and dry soil).
(ii) Loss of water as droplets through leaves of
228. Define wilting. an intact plant is termed (bleeding, guttation,
Ans : MAIN 2018 transpiration).
CH 4 : TRANSPIRATION

208. Mention three adaptations found in plants to Exudation of plant sap through the injured part
reduce transpiration. of a plant is called bleeding.
Ans : SQP 2012
217. What is cuticle?
(a) Presence of sunken stomata. Ans : SQP 2010
(b) Leaf may be modified into spines.
(c) Presence of thick cuticle on the epidermis. It is a non-cellular layer secreted by the epidermal
cells.
209. Explain the term Guttation.
218. What is lenticel?
Ans : COMP 2018
Ans : COMP 2001
The process of removal of water in the form of
drops of water through hydathodes. Guttation The opening present on the bark of woody stem.
occurs due to increased hydrostatic pressure that
develops within the cells.

210. Define transpiration. TWO MARKS QUESTIONS

Ans : COMP 2023

The loss of water in the form of water vapour 219. How does the rate of Transpiration differ when
through the aerial parts of a plant. there is :
(a) High temperature
211. What are anti-transpirants ?
(b) High humidity
Ans : MAIN 2009
Ans : SQP 2025
Chemicals used to reduce excessive transpiration
(a) Increases
in the plant leaves.
(b) Decreases
212. Name three factors which affects transpiration.
220. Write the overall chemical equation for
Ans : COMP 2004 Photosynthesis.
(a) Sunlight, (b) Humidity, (c) Wind. Ans : SQP 2025

Sunlight
213. How are guard cells adapted for transpiration ? 6CO 2 + 12H 2 O C 6 H 12 O 6 + 6H 2 O + 6O 2
Chlorophyll

Ans : SQP 2016

The outer wall of guard cell is thin while the inner 221. Mention Two advantages of transpiration.
wall is thick. The guard cells control the opening Ans : MAIN 2024
and closing of stomata by changing their turgidity.
Advantages of transpiration :
214. Why do plants absorb more water than required ? (i) Transpiration helps to cool plants and regulate
their temperature. As water evaporates from
Ans : MAIN 2019 the leaves, it takes up heat energy, thus
To get sufficient minerals plants have to absorb lowering the temperature of the plant.
water. (ii) Transpiration creates a suction force that
helps to draw water and nutrients from the
215. How does sunlight affect transpiration ? soil into the plant roots. This process is
Ans : SQP 2013 essential for the growth and development of
plants.
Sunlight affects transpiration in two ways:
(a) During day time, photosynthesis takes place 222. Mention the limitations of potometer.
and guard cells open stomata.
Ans : MAIN 2022
(b) It increases the temperature of the leaves.
(a) Introducing the air bubble is not very easy.
216. What is bleeding? (b) Any change in the outside air temperature
Ans : MAIN 2021 may affect the position of air bubble in the
capillary tube.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 143

240. Explain forests bring rain. Inference Cobalt chloride strip turns pink because
of water. Since the strip of cobalt chloride fixed
Ans : MAIN 2013
on the lower surface turns pink in lesser time, it
Trees absorb water through the roots and the proves that the loss of water (transpiration) from
excess water in the form of water vapour is the lower surface is more.
given out by the tree leaves through the process
of transpiration. Trees produce 10 times more 242. The figure below represents an experiment
water vapours than herbaceous plants. The water performed to demonstrate certain phenomenon in
vapours when it rises up in the atmosphere cools plants. The set-up was kept in sunlight for about
and forms water. These condensed water forms two hours:
clouds that precipitates to the earth’s surface in (i) What is the aim of the experiment ?
the form of rain, hail or snow. Therefore, trees or (ii) Define the process mentioned in (i) above.
forest brings rain to the surrounding area. (iii) What do you observe in the experiment as an
evidence of the process stated in (i) and (ii)
above ?
(iv) What precautions are taken for proper results
FIVE MARKS QUESTIONS in the experiment ?
(v) Suggest a suitable control experiment for
comparison.
241. Describe an experiment to prove that transpiration
occurs more from the under surface of dorsiventral
leaves.
Ans : COMP 2004, 1997

Aim : To demonstrate that more transpiration

occurs from the lower surface of a dorsiventral
leaf as compared to upper surface.

Ans : SQP 2019, 1993

(i) To demonstrate the phenomenon of

Transpiration.
(ii) Transpiration is the loss of water from aerial
Requirements : A well-watered potted plant parts of the plants in the form of water
with broad leaves, dry cobalt chloride strips, leaf vapours.
clamps. (iii) The water droplets can be seen on the inner
Procedure : Fix dry cobalt chloride strips on both surface of the polythene bag.
the surfaces of a leaf of the potted plant with the (iv) (1) The apparatus must not be kept in a very
help of leaf clamps as in Figure. hot place as the water vapour will not
Observe the changes in the colour of cobalt condense.
chloride strips on both the surfaces at the same (2) Polythene bag must be air tight to
time. prevent the entry of water vapour from
Observations : Cobalt chloride strip fixed on the outside.
lower surface of the leaf turns pink much earlier (v) Take a pot without plant covered with
as compared to the one that is fixed on the upper polythene bag.
surface.
CH 4 : TRANSPIRATION

243. The given diagram represents an experiment to (ii) Name the parts numbered 1-5.
demonstrate a certain phenomenon in a green (iii) What is the most apparent difference between
plant. A and B in the structure shown ?
(i) Has the level of mercury in the glass tubing (iv) Describe the mechanism which brings about
risen or fallen ? the change in the structure depicted in A and
(ii) Name the life process of the plant which has B.
caused the change in the level of mercury.
Ans : COMP 2017, 1999
(iii) Define the process named above.
(iv) State any three advantages of this process to (i) The structure shown are the stomata present
the plant. in the epidermal layer of the leaf.
(v) Which conducting tissue of the plant does the (ii) 1. Guard cell,
glass-tubing represent-xylem or phloem ? 2. Thickening of the inner walls of the guard
cell,
3. Nucleus of the guard cell,
4. Outer thin cell-wall,
5. Stomata.
(iii) In A, the stomata is open while in B, the
stomata is closed.
(iv) The opening and closing of the stomata are
due to the change in turgidity of the guard
cells and this change is mainly connected with
two factors – Light and Water. In the presence
of light, the guard cells photosynthesise,
sugar produced increase osmotic pressure
and they absorb water from the neighbouring
cells by endosmosis expand and bulge out
in an outward direction; and the stomata
opens as in A. In the absence of light, the
guard cells lose water and become flaccid,
Ans : MAIN 2008, 1995 and the stomata closes. The intensity of light
also directly affects the degree of stomatal
(i) The level of mercury in the glass tubing has
opening.
risen.
(ii) Transpiration. 245. An apparatus as shown below was set-up to
(iii) Loss of water in the form of vapours from the investigate a physiological process in plants. The
aerial parts of a plant is called transpiration. set-up was kept in sunlight for two hours. Droplets
(iv) (a) It helps in absorption of water by roots. of water were then seen inside the bell jar. Answer
(b) It helps in absorption of minerals from the questions that follow :
soil water.
(c) It helps in movement of water in the
plants.
(v) Xylem.

244. Given below are the diagrams of a certain

structure in plants in two conditions.

(i) Name the structure shown.

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 145

(i) Name the process being studied. the aerial exposed parts of a plant is called
(ii) Explain the process named above in (i). transpiration.
(iii) Why was the pot covered with a plastic sheet? (iv) The first limitation of this apparatus is that it
(iv) Suggest a suitable control for this experiment. is very difficult to introduce the air bubble at
the lower end of the capillary tube. Secondly,
(v) Mention two ways in which this process is
various changes in the environment such as,
beneficial to plants.
temperature, humidity, air velocity etc. may
(vi) List three adaptations in plants to reduce the
influence the position of air bubble.
above mentioned process.
(v) Rate of water uptake can be calculated by
Ans : MAIN 2015 timing the air bubble movement over a fixed
distance on the scale.
(i) The process is Transpiration.
(vi) Transpiration takes place through stomata,
(ii) Transpiration is the loss of water in the form
cuticle and lenticels.
of vapours from the aerial parts of the plant.
(iii) The pot is covered with plastic sheet in order 247. The diagram below represents a process in plants.
to avoid evaporation of water from the pot. The setup was placed in bright sunlight. Answer
(iv) The control of this experiment is that the the following questions :
plant must be removed from the set-up.
(v) Ascent of sap/absorption of water/transport
of minerals/cooling effect
(vi) Thick cuticle/loss of leaves/narrow leaves/
fewer stomata/sunken stomata.

246. The diagram of an apparatus given below demon-

strates a particular process in plants. Study the
same and answer the questions that follow :

(i) Name the physiological process depicted in

the diagram.
Why was oil added to the water?
(ii) When placed in bright sunlight for four hours,
what do you observe with regard to the initial
(i) Name the apparatus. and final weight of the plant?
(ii) Which phenomenon is demonstrated by this Give a suitable reason for your answer.
apparatus ? (iii) What happens to the level of water when this
(iii) Explain the phenomenon mentioned in (ii) setup is placed in:
above. 1. Humid conditions?
(iv) State two limitations of using this apparatus. 2. Windy conditions?
(v) What is the importance of the air bubble in (iv) Mention any three adaptations found in
the experiment ? plants to overcome the process mentioned in
(vi) Name the structures in a plant through which (i).
the above process takes place. (v) Explain the term ‘Guttation’.
Ans : SQP 2016 Ans : COMP 2018

(i) Ganong’s potometer. (i) Transpiration.

(ii) Rate of transpiration. Oil was added in order to prevent evaporation
(iii) The loss of water in the form of vapours from from the round bottom flask.
CH 4 : TRANSPIRATION

increase the rate of transpiration. water.

(iii) During day the stomata are open to facilitate (v) The adaptations in plants are:
the inward diffusion of carbon dioxide for 1. Sunken stomata.
photosynthesis and water vapours are also 2. Less number of stomata.
lost to the outside during transpiration. 3. Modification of leaves to spines.
(iv) 1. The rate of transpiration on a windy day 4. Narrow leaves/curled leaves
will increase because the water vapour
will not be allowed to accumulate near 254. Given below is the diagram of an experimental set
the leaves. up to study the process of transpiration in plants.
2. The rate of transpiration on a foggy day Study the same and then answer the questions
will decrease because of the rise of the that follow :
rate of water vapour in the atmosphere.
(v) The leaves of certain plants roll up on a bright
sunny day, to reduce the exposed surface to
reduce transpiration.

253. An apparatus as shown below was set-up to

investigate a physiological process in plants. The
set-up was kept in sunlight for two hours. Droplets
of water were then seen inside the bell jar.

(i) What is the colour of dry cobalt chloride

paper ?
(ii) Is the experimental leaf a monocot or a dicot?
Give a reason to support your answer.
(iii) Why are glass slides placed over the dry
cobalt chloride papers ?
(iv) After about half an hour, what change, if any,
would you expect to find in the cobalt chloride
paper placed on the dorsal and ventral sides
of the leaf ? Give a reason to support your
answer.
(i) Name the process being studied. (v) Define the term ‘transpiration’.
(ii) Why was the pot covered with a plastic sheet? Ans : SQP 2006, 1992
(iii) Suggest a suitable control for this experiment.
(iv) Mention two ways in which this process is (i) Blue.
beneficial to plants. (ii) Dicot leaf. Because the leaf has reticulate
(v) List three adaptations in plants to reduce the venation.
above mentioned process. (iii) To keep the strips of cobalt chloride paper at
their places.
Ans : MAIN 2015
(iv) The dorsal cobalt chloride paper will turn
(i) Transpiration. pink less; while on ventral side it will turn
(ii) It is covered with plastic sheet to prevent the pink more.
evaporation of water. (v) It is a process in which the water is lost in the
(iii) Take an empty polythene bag with its mouth form of vapours from the aerial parts of the
tied and keep it in sunlight. plant.
(iv) The two ways in which it is beneficial for the
plants: 255. Describe any Three conditions which affect
1. Cooling effect. transpiration.
2. It creates a suction force to absorb more Ans : SQP 2007, 1994
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 147
Ans : SQP 2019
(iv) (1) Sunken stomata
(i) Transpiration, It is the loss of water in the (2) Thick cuticle
form of water vapour from aerial exposed (3) Narrow leaves
parts of plants. (4) Modification of leaves into spines.
(ii) To prevent escape of water vapour from the
pot. 251. The figure given below represents an experimental
(iii) - Intensity of sunlight set up with a weighing machine to demonstrate
- Increase in temperature a particular process in plants. The experimental
(iv) - Sunken stomata set up was placed in bright sunlight. Study the
- Thick cuticle diagram and answer the following questions:
(v)

(i) Name the process intended for study.

(ii) When the weight of the test tube (A and B) is
taken before and after the experiment, what
is observed ? Give reasons to justify your
250. Given is an experimental set up to demonstrate a observation in A and B.
particular process. (iii) What is the purpose of keeping the test tube
Study the same and answer the question that B in the experimental set up ?
follow:
Ans : SQP 2014

(i) Transpiration.
(ii) It is observed in test tube A that after the
experiment, the weight has decreased, and in
test tube B, the weight remains same.
In test tube A, transpiration took place and
weight decreased. In test tube B is used as a
control, no plant is kept, oil is added and so,
no transpiration has taken place.
(i) Name the physiological process being studied. (iii) Test tube B is a control.
(ii) What is the aim of the above experiment?
(iii) What would you observe in the experimental 252. Explain briefly :
set-up after an hour? (i) Xerophytes have their leaves modified to
Give a reason to support your answer. spines or reduced in size.
(iv) Mention any three adaptations found in (ii) A higher rate of transpiration is recorded on
plants to overcome the physiological process a windy day rather than on a calm day.
mentioned in (i) above. (iii) During the day transpiration and
photosynthesis are interlinked.
Ans : COMP 2012
(iv) How the rate of transpiration is affected on :
(i) Transpiration 1. a windy day
(ii) To show that the rate of transpiration is more 2. a foggy day.
on the ventral surface of the leaf than the (v) The leaves of certain plants roll up on a bright
dorsal surface. sunny day.
(iii) The cobalt chloride paper on the ventral
Ans : MAIN 2010, 2006, 1999, 1995
surface turns pink faster than the dorsal side
as more stomata are present on the ventral (i) To reduce water loss in order to conserve it.
surface. Hence, more transpiration. (ii) Wind is the external factor which helps in to
CH 4 : TRANSPIRATION

(ii) The plant will loose weight as in bright (d) Upper surface – more pink, Lower surface
sunlight, the rate of transpiration will be – less pink.
maximum. (iv) Two adaptations in plants to reduce
(iii) 1. Remains same Transpiration are :
2. Decreases (a) Narrow leaves, Thin cuticle,
(iv) Thick cuticle/loss of leaves/narrow leaves/ (b) Fewer stomata, Broad lamina of leaves.
fewer stomata/sunken stomata (c) Thin cuticle, Sunken stomata.
(v) Loss of water in the form of liquid as droplets (d) Narrow leaves, Fewer stomata.
from the margins of leaves is called guttation. (v) The rate of transpiration is less when there is:
(a) High humidity in the air and low
248. Given below is the diagram of an experimental temperature.
setup to study the process of Transpiration. (b) Less humidity in the air and decrease in
Cobalt chloride papers are fixed on the upper as atmospheric pressure.
well as lower surface of the leaf. (c) Bright sunlight and high temperature.
(d) More wind and low intensity of sunlight.
Ans : COMP 2021

(i) (a) To prove that more transpiration occurs

from the lower surface of a dicot leaf
(ii) (b) Blue
(iii) (c) Upper surface – less pink, lower surface –
more pink.
(iv) (d) Narrow leaves, Fewer stomata
(v) (a) High humidity in the air and low
temperature.

249.

Answer the questions that follow :

(i) What is the aim of the experiment ?
(a) To prove that more transpiration occurs
from the lower surface of a dicot leaf
(b) To prove that more transpiration occurs
from the copper surface of a dicot leaf.
(c) To prove that transpiration is equal on
both sides of the leaf
(d) To prove that transpiration does not take
place in a dicot leaf
(ii) What is the colour of dry cobalt chloride
paper ?
(a) Pink
(b) Blue
(c) Brown
(d) White
(iii) After about an hour, what change if any, (i) Name the process being studied. Define the
would you expect to find in the cobalt chloride process.
paper placed on the upper and lower surface (ii) Why was the pot enclosed in a rubber sheet ?
of the leaf? (iii) Mention two external factors which can
(a) Upper surface – Pink, Lower Surface – accelerate the above process.
Blue. (iv) List two adaptations in plants to reduce the
(b) Upper surface – White, Lower surface – above process.
Blue. (v) Draw a neat, labelled diagram of a stomatal
(c) Upper surface – less pink, Lower surface apparatus.
– more pink.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 149

The conditions which affect transpiration are as 3. Why is stomatal transpiration more common
follows : in most plants?
(i) Light : It may be considered one of the most 4. Explain the role of lenticels in transpiration
important environmental factors because of for woody plants.
its role in causing stomata to open. Besides,
Ans :
the light increases the temperature of the leaf
which in turn brings about an increase in 1. Stomatal
transpiration. 2. Environment
(ii) Temperature : An increase in temperature 3. Efficiency
brings about a decrease in the relative 4. Openings
humidity of the air and this in turn increases 258. A researcher finds that guard cells control stomatal
the rate of transpiration. opening by swelling with water in the presence of
(iii) Humidity of the Atmosphere : The rate light. Potassium ions play an essential role in this
of transpiration is directly related to the regulation, and the stomata close when it’s dark.
vapour pressure of the atmosphere. The rate 1. Describe the role of guard cells in stomatal
of transpiration decreases with the rise in regulation.
vapour pressure in the atmospheric air and it 2. How does light affect the opening and closing
increases with the fall in vapour pressure. of stomata?
3. Explain the role of potassium ions in stomatal
movement.
4. What changes occur in guard cells during
CASE BASED QUESTION darkness?
Ans :
256. A gardener notices that his plants wilt during hot, 1. Control
dry afternoons, even with regular watering. He 2. Open
observes water being absorbed by the roots and 3. Turgidity
transported upward, but it is quickly lost. The 4. Close
gardener wants to understand why the plants are
losing so much water. 259. A plant physiologist is experimenting to
1. Explain the role of transpiration in water understand how factors like light, temperature,
movement through the plant. humidity, and wind speed affect water loss
2. How do environmental conditions like heat through transpiration in plants.
and dryness affect transpiration? 1. How does light intensity influence the rate of
3. What is the importance of root water transpiration?
absorption in preventing wilting? 2. Explain the effect of temperature on
4. Suggest ways to reduce water loss from plants transpiration rates.
in hot weather. 3. Why does low humidity increase transpiration
in plants?
Ans : 4. How does wind speed contribute to water loss
1. Ascent in plants?
2. Increase Ans :
3. Turgidity
4. Mulching 1. Increase
2. Increase
257. A botany student is studying how plants lose 3. Gradient
water. She observes that plants lose water through 4. Velocity
the cuticle, lenticels, and stomata under different
environmental conditions. 260. A researcher is studying how environmental
1. Differentiate between cuticular, lenticular, factors affect the opening and closing of certain
and stomatal transpiration. plant structures under varying conditions. He uses
2. How do environmental factors influence each diagrams that show the structure in two different
type of transpiration? states (A and B)
CH 4 : TRANSPIRATION

(i) What is the purpose of keeping CaCl2 vials

inside the cup?
(ii) After a few hours, CaCl2 vials were taken
out and weighed again. Will you expect any
difference in weight ? If so, give reasons.
(iii) What was the purpose of using a manometer?
(iv) What do you mean by transpiration ?
(i) Name the structure shown. Ans : COMP 2004

(ii) Name the parts numbered 1-5. (i) To absorb the moisture formed by
(iii) What is the most apparent difference between transpiration.
A and B in the structure shown? (ii) Yes, the weight of CaCl2 vial kept on the
(iv) Describe the mechanism which brings about lower side will be more as moisture has been
the change in the structure depicted in A and absorbed because transpiration is more on
B. the lower surface of the leaves.
Ans : SQP 2019 (iii) To check the outside and inside pressures.
(iv) The loss of water in the form of water vapour
(i) Stomata
from the aerial parts of a plant.
(ii) 1. Chloroplast; 2. Inner wall of guard cell; 3.
Nucleus; 4. Outer wall of guard cell; 5. Stoma. 262. A botanist is conducting an experiment using
(iii) In A, the stoma is open. In B, it is closed. three plants (A, B, and C) placed in beakers of
(iv) The guard cells have thick inner wall and water. The water in each beaker is covered with a
a thin outer wall. Guard cells contain layer of oil to prevent evaporation. Plant B has its
chloroplast which synthesises glucose and leaves removed, and plant C is exposed to strong
increases osmotic pressure and draws water light.
inside and cells become turgid and bulge
outward and widening the stomatal opening.
During night, reverse process occurs and cells
become flaccid and close.

261. The apparatus shown is Garreau’s potometer

designed to demonstrate unequal transpiration
from the two surfaces of a dorsiventral leaf. Before
keeping the leaf in between the cups, anhydrous
calcium chloride (CaCl2) contained in two small
vials were weighed and placed in both the cups.
The ends of the cups were closed with corks
through which two mercury manometers were (i) In which plant A, B or C would the water
connected. move up fastest?
(ii) In which plant would water move slowly?
(iii) Why is the water covered with oil?
(iv) What is being investigated by this experiment?
Ans : MAIN 2013

(i) In plant C, water would move up fastest as

the rate of transpiration is high due to the
heat emitted by the strong light (bulb).
(ii) In plant B, water would move slowly as there
are no leaves.
(iii) The water is covered with oil to check the loss
of water by evaporation from the surface.
(iv) It is being investigated whether the intensity
of light has a direct effect on the rate of
transpiration.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 151
Ans : SQP 2009

(i) The apparatus is called as Potometer.

(ii) (a) In dark, speed of movement of air bubble
slows down.
(b) In bright sunlight, speed of movement of
air bubble increases.
(c) In front of a blower, the speed of
movement of air bubble increases.
(iii) The rate of transpiration increases in
sunlight. The rate of transpiration increases
with moving air.

263. The experiment set up shown in the diagram

represents a particular phenomenon in plants.
(i) What happens to the level of mercury in the
tube.
(ii) Account for your answer in part (i).
(iii) What is likely to happen if the bulb is
switched

(iv) Name the structures in plants which are

equivalent to the following parts in the
diagram :
(a) Porous pot, (b) Pores in pot, (c) Tube.
Ans : MAIN 2018

(i) The level of mercury rises.

(ii) When the bulb glows evaporation of water
takes place from the porous pot. This creates
a suction force due to which the level of water,
hence mercury increases in the tube.
(iii) When the bulb is switched off the rate at
which mercury is rising in the tube slows
down.
(iv) (a) Leaves (leaf),
(b) Stomata,
(c) Xylem.

www.nodia.in
CH 5 : PHOTOSYNTHESIS

CHAPTER 5
PHOTOSYNTHESIS

of absorbing a mole quantum of light.

SUMMARY There are about 40 to 50 chloroplasts present in
each leaf cell.
1. PHOTOSYNTHESIS 1.2 Pigments Involved in Photosynthesis
It is a light energy trapping process in which Pigments are substances which absorb certain
energy of sunlight is transduced to chemical energy wavelength of visible light. Different colours
that is the ultimate source of food for almost all of pigments are due to the visible spectrum
living organisms. The energy rich compounds like which they reflect or transmit. Chlorophylls and
carbohydrates are formed from water and carbon carotenoids are two major groups of pigments
dioxide using light energy absorbed by chlorophyll found in higher plants. Chlorophylls (the green
from the sunlight. pigment of plants) are most important pigments
Photosynthesis means to put together by light, active in photosynthetic process. Carotenoids
is the only process on earth by which solar energy are large group of hydrocarbon pigments found
is converted into chemical energy by autotrophic throughout the plant. Carotenes (red coloured)
organisms. Upto 90% of total photosynthesis and xanthophylls (yellow coloured) are two
takes place in the oceans. important groups of carotenoids. They are usually
1.1 Chloroplast the Site of Photosynthesis masked by green chlorophylls but can be seen in
leaves prior to leaf fall since chlorophylls break
The entire photosynthetic machinery lies in down first. Carotenoids protect photo-oxidation
chloroplasts, the green coloured plastids found of chlorophyll and absorb and transfer light
in green coloured parts of plants, which were energy to chlorophyll molecules.
discovered by Robert Hill. A chloroplast is
enclosed by a double membrane of lipoprotein. 1.3 Requirements of Photosynthesis
The space enclosed by the double membraned Light, chlorophyll, carbon dioxide and water
envelope is the stroma, the site of dark reaction are essential requirements for photosynthesis.
of photosynthesis. The inner membrane of Light is needed for some but not all reactions of
chloroplast extends at several points across it photosynthesis. There is a light dependent stage
to form a lamellar system. These lamellae are of photosynthesis and also a light independent
stacked on top of each other to form grana, the stage in which reactions occur in the absence of
centre of light reaction of photosynthesis. light.
For most plants the source of light energy
for the reactions of the light dependent stage is
the sun. A source of carbon is needed for the
synthesis of sugars. Carbon dioxide from the
air or in solution or as hydrogen carbonate ions
(HCO3) in water, is the only carbon source which
Each granum is composed of 5-25 discs and plants can use in photosynthesis. Carbon dioxide
each disc said to be thylakoid encloses a space. alone is not sufficient to produce carbohydrates.
On the inner surface of the lamellar membrane Hydrogen ions are needed too and water is the
small spherical structures, called quantasomes are only source of hydrogen ions that plants can make
present, which are the structural and functional use of. The final requirement for photosynthesis
units of chloroplast. Each quantasome is capable is a means of capturing the energy from the sun.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 153

The photosynthetic pigment chlorophyll carries Glucose produced during photosynthesis is

this role. soluble in water and consists of small molecules.
As soon as glucose is produced it is converted
2. MECHANISM OF PHOTOSYNTHESIS into starch (insoluble in water) by the process of
Photosynthesis is an oxidation – reduction polymerization.
process in which water is oxidized to oxygen
and carbon dioxide is reduced to carbohydrates. 3. PHOTORESPIRATION
Mesophyll cells in the leaves are the main centre The process of uptake of oxygen and production of
of photosynthesis and this process is not a single carbon dioxide in light by photosynthesizing tissue
step process, rather it involves many steps. The is called photorespiration. A large proportion of
various steps which are involved in photosynthesis carbon dioxide assimilated by photosynthesis is
are divided in two distinct but related phases. lost through photorespiration.
These are :
(1) Light reaction (Photochemical phase or light 3.1 Adaptation in Leaf for Photosynthesis
dependent phase or Hill reaction). To perform the function of photosynthesis
(2) Dark reaction (Biosynthetic phase or light efficiently, rapidly and sufficiently, the leaves
independent phase or Blackmans reaction). undergo for some structural changes which are as
follow :
2.1 Light Reaction Large surface area, leaf arrangement on stem,
This phase occurs in the thylakoids of chloroplast. presence of chloroplasts, numerous stomata,
In this phase light energy is absorbed by thinness of leaf and network of veins.
chlorophyll pigment and is converted into chemical
energy which is stored in the energy rich ATP 3.2 Factors Influencing Photosynthesis
molecules. A substance NADP (Nicotinamide There are external as well as internal factors
adenine dinucleotide phosphate) is converted into which affect the rate of photosynthesis. External
a reducing substance NADPH, which is generated factors include light, carbon dioxide, temperature,
at the same time. oxygen and water contents. Several aspects of leaf
There is photolysis of water which leads to anatomy like thickness of cuticle, distribution of
the evolution of molecular oxygen. At the same stomata and development palisade and vascular
time generation of ATP from ADP also occurs. tissue also influence the rate of photosynthesis
This process is called photophosphorylation. by influencing the diffusion of carbon dioxide
Hence, in light reaction the end products are through stomata.
NADPH and ATP which are further used in the Maximum photosynthesis occurs in red and blue
dark reaction of photosynthesis to fix and reduce light while in green light it is the least.
carbon dioxide.
3.3 Translocation of Organic Compounds
2.2 Dark Reaction (Photosynthates) in Plants
Dark reaction does not mean that it takes place The movement of organic matter from the place
at night or darkness. It simply means that dark of its synthesis to other parts of the plant through
reaction does not require light energy. This stage special conducting tissue, the phloem, is called
occurs in the stroma of the chloroplast. Dark translocation of photosynthates.
reaction involves the fixation and reduction Carbohyrates formed in photosynthesis are used
of carbon dioxide resulting in the formation of up in three main ways :-
carbohydrates by utilizing ATP and NADPH
obtained as a result of the light reaction. 3.4 Fate of Carbohydrates Formed in Photosynthsis
The primary acceptor of atmospheric carbon 1. Respiration : Most cells receive sugar
dioxide is RuBP (Ribulose bi phosphate) in the through phloem. This is broken down during
beginning of this stage. At the end of the cycle respiration to liberate energy the cells require.
glucose is synthesized and RuBP is regenerated. 2. Food storage : Some of the sugar may be
The Overall reaction of this phase is : stored for future use either in organs such as
6RuBP + 6CO2 + 18ATP + 12NADPH + 12H+ bulbs, tubers, corms or rhizomes or for the
$ 6RuBP + C6H12O6 + 18ADP + 18Pi + next generation in seeds or fruits. Usually the
12NADP + 6H2O sugar is converted into starch for storage but
CH 5 : PHOTOSYNTHESIS

The dark reaction, also called the Calvin cycle, Ans : SQP 2002

fixes carbon dioxide to form glucose. Oxygen is produced during the photolysis of water
Thus, (b) is the correct option. in the light-dependent reactions of photosynthesis.
Thus, (b) is the correct option.
25. What is the source of hydrogen ions used during
photosynthesis? 30. What process in photosynthesis involves the
(a) Glucose formation of ATP from ADP and Pi using light
(b) Water energy?
(c) Oxygen (a) Photophosphorylation
(d) ATP (b) Photolysis
Ans : COMP 2003
(c) Polymerization
(d) Photorespiration
Water is split during the light reaction to release
hydrogen ions, electrons, and oxygen. Ans : MAIN 2013

Thus, (b) is the correct option. Photophosphorylation is the process of generating

ATP using light energy during the light-dependent
26. Which light is least effective in photosynthesis? reactions.
(a) Red Thus, (a) is the correct option.
(b) Blue
(c) Green 31. Which molecule is regenerated at the end of the
(d) Yellow Calvin cycle?
Ans : SQP 2014
(a) Glucose
(b) RuBP
Green light is least effective because chlorophyll (c) ATP
reflects green light and does not absorb it. (d) NADPH
Thus, (c) is the correct option.
Ans : COMP 2009
27. What is the function of carotenoids in Ribulose bisphosphate (RuBP) is regenerated at
photosynthesis? the end of the Calvin cycle to accept more carbon
(a) Absorb green light dioxide.
(b) Protect chlorophyll from photo-oxidation Thus, (b) is the correct option.
(c) Produce ATP
(d) Absorb carbon dioxide 32. What experiment is commonly used to demonstrate
Ans : MAIN 2010
that light is necessary for photosynthesis?
(a) Test with methylated spirit
Carotenoids absorb light and protect chlorophyll (b) Ganong's light screen experiment
from photo-oxidation, preventing damage from (c) Test with iodine
excess light. (d) Variegated leaf test
Thus, (b) is the correct option.
Ans : SQP 2005
28. Which element is not required for the process of Ganong's light screen experiment is used
photosynthesis? to demonstrate that light is necessary for
(a) Light photosynthesis by covering part of a leaf and
(b) Carbon dioxide showing that photosynthesis does not occur in the
(c) Water covered part.
(d) Nitrogen Thus, (b) is the correct option.
Ans : COMP 2006
33. Which plants are used to demonstrate the
Explanation: Nitrogen is essential for plant growth evolution of oxygen during photosynthesis?
but not directly required for photosynthesis. (a) Potato and tomato
Thus, (d) is the correct option. (b) Hydrilla and Elodia
(c) Cacti and succulents
29. What gas is evolved during photosynthesis?
(d) Wheat and rice
(a) Carbon dioxide (b) Oxygen
(c) Nitrogen (d) Methane Ans : MAIN 2002
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 155

4. NADP is expanded as : Pond weed was placed in five water-filled tubes.

(a) Nicotinamide Adenosine Dinucleotide Phosphate. The experiment was set-up shown in the diagram.
(b) Nicotinamide Adenine Dinucleotide Phosphate. The tubes were then left for 24 hours
(c) Nicotinamide Adenine Dinucleolus Phosphate. Write the correct answer out of the five available
(d) Nicotinamide Adenosine Dinucleolus Phosphate. choices given under each question.
(i) In which tube would you expect the greatest
Ans : COMP 2021
increase in dry weight of the pond weed ?
The full form of NADP is nicotinamide adenine (a) 1 (b) 2
dinucleotide phosphate which will become (c) 3 (d) 4
NADPH (nicotinamide adenine dinucleotide (e) 5
phosphate + hydrogen) after reduction.
Thus (b) is correct option. Ans : COMP 2021

Because the snail provides carbon dioxide through

5. Photosynthesis : its respiration and thus, more photosynthetic
(a) It is the synthesis of glucose from carbon activity takes place.
dioxide by non-green plants using light energy. Thus (b) is correct option.
(b) It is the synthesis of glucose by green plants
(ii) In which tube would you expect to find the
from carbon dioxide using light energy.
plant with the least amount of starch ?
(c) It is the synthesis of glucose from carbon
(a) 1 (b) 2
dioxide and water by non-green plants using
(c) 3 (d) 4
light energy.
(e) 5
(d) It is the synthesis of glucose from carbon
dioxide and water by non-green plants using Ans : COMP 2021
light energy. Because the plant is in dark. So there will be no
Ans : MAIN 2021 photosynthesis.
Thus (e) is correct option.
Thus (d) is correct option.
(iii) The tube in which most oxygen would be
6. A plant biologist is examining the structure of found is:
chloroplasts, specifically the role of the grana in (a) 1 (b) 2
photosynthesis. She wants to determine which (c) 3 (d) 4
processes do not take place in the grana. Grana of (e) 5
chloroplast is not the :
Ans : COMP 2021
(a) Site of Light Independent Phase.
(b) Site of Light Dependent Phase. Because it is in full light and no animal is present
(c) Site of Photolysis. to utilize the oxygen released by the plant
(d) Site of Photon absorption. Thus (a) is correct option.
Ans : SQP 2021 (iv) The tube in which least carbon dioxide would
be found is :
In C4 plants, agranal chloroplast is present in
(a) 1 (b) 2
bundle sheath cells. E.g sugarcane leaf.
(c) 3 (d) 4
Thus (a) is correct option.
(e) 5
7. The following diagram is a setup to demonstrate Ans : COMP 2021
an experiment.
Because no snail to release carbon dioxide and the
plant is utilizing the existing gas.
Thus (a) is correct option.
(v) The tube in which the plant would survive for
the shortest length of time is :
(a) 1 (b) 2
(c) 3 (d) 4
(e) 5
Ans : COMP 2021
CH 5 : PHOTOSYNTHESIS

quite often it is stored as sucrose as in sugar for photosynthesis. Variegated leaves are those
cane. In fact, many of our vegetables are really leaves which have green and yellow patches and
plant food storage organs. For example, potato chlorophyll is present in the green patches only.
tubers are storage stems, carrot, turnip and Examples of plants with variegated leaves are –
beet roots are storage roots. In many cases, Croton, Coleus, Geranium and Tradescantia.
carbohydrates are converted to oils for storage
example mustard oil and groundnut oil.
3. Growth : Sugar is also transported to actively
growing parts of the plant where these MULTIPLE CHOICE QUESTION
provide energy and are used in the formation
of cellulose, fats and proteins.
1. The process of conversion of ADP to ATP during
3.5 Importance of Photosynthesis photosynthesis is called:
It is a process upon which all life on Earth (a) Photolysis
depends directly or indirectly. Both carbon (b) Phagocylosis
dioxide and energy are made available to all (c) Photophosphorylation
living organisms by this process. Oxygen is also (d) Polymerisation
produced in the atmosphere which is vital for all
aerobic organisms. It is the only process on Earth Ans : MAIN 2024

by which solar energy is trapped by autotrophic Photophosphorylation involves the

organisms and is converted into food for the rest Photophosphorylation of ADP (adenosine
of the organisms. diphosphate) to form ATP (adenosine
Only 0.2.% of the light energy falling on Earth triphosphate) using the energy derived from light
is utilized by photosynthetic organisms. Even during photosynthesis.
this much amount of trapped energy is sufficient Thus (c) is correct option.
to meet the food requirements of all other
heterotrophs. Not only this, people obtain fodder, 2. The individual flattened stacks of membranous
firewood, timber and fibres from the plants. Fossil structures inside the chloroplasts are known as:
fuels like coal, petroleum and natural gas also are (a) Grana (b) Stroma
the products of photosynthetic organisms which (c) Thylakoids (d) Cristae
lived millions of years ago. Ans : MAIN 2016

3.6 Experiments on Photosynthesis Thylakoids consist of a thylakoid membrane

surrounding a thylakoid lumen. Chloroplast
Simple experiments can be performed to prove
thylakoids frequently form stacks of disks referred
the importance of various conditions and
to as grana. So the correct option is 'Thylakoid'.
requirements for photosynthesis. In all such
Thus (c) is correct option.
experiments the basic principle is to use a green
potted plant whose leaves has been made starch 3. A biologist studies how ADP is converted to
free (destarched). ATP during photosynthesis under different light
Destarching a plant ensures that any conditions. The process of conversion of ADP to
starch present after the experiment has been ATP during Photosynthesis :
formed under experimental conditions. Hence (a) Polymerisation.
it is necessary to destarch a plant before the (b) Photophosphorylation.
experiment on photosynthesis.
(c) Photorespiration.
Hydrilla, Vallisneria and Elodia are water
(d) Photolysis.
plants and can be used to demonstrate an
experiment to prove that oxygen is evolved during Ans : SQP 2021
photosynthesis.
The process of conversion of ADP to form
Methylated spirit and alcohol dissolves chlorophyll.
ATP using the energy of sunlight during the
Iodine solution turns blue black in the presence
first phase of photosynthesis is termed as
of starch.
photophosphorylation.
Ganongs light screen is used in the
Thus (b) is correct option.
experiment to demonstrate that light is necessary
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 157

16. What role do carotenoids play in photosynthesis? 20. What is the primary acceptor of atmospheric
(a) They produce oxygen carbon dioxide in the dark reaction?
(b) They absorb and transfer light energy to (a) 4RuBP (b) ATP
chlorophyll (c) NADP (d) Chlorophyll
(c) They convert light energy into chemical
Ans : SQP 2004
energy
(d) They break down chlorophyll In the dark reaction, carbon dioxide is fixed by
combining with Ribulose bisphosphate (RuBP).
Ans : COMP 2005
Thus, (a) is the correct option.
Carotenoids absorb light and transfer the
energy to chlorophyll, aiding in the process of 21. The process of conversion of glucose into starch in
photosynthesis. They also protect chlorophyll plants is known as:
from photo-oxidation. (a) Photophosphorylation
Thus (b) is correct option. (b) Polymerization
(c) Photorespiration
17. What is the source of hydrogen ions in (d) Photolysis
photosynthesis?
Ans : MAIN 2000
(a) Carbon dioxide
(b) Water The conversion of soluble glucose into insoluble
(c) Oxygen starch is called polymerization.
(d) Chlorophyll Thus, (b) is the correct option.

Ans : SQP 2016 22. What happens during photorespiration?

During photosynthesis, water is split in the light- (a) Uptake of oxygen and production of carbon
dependent reactions, releasing hydrogen ions, dioxide
electrons, and oxygen. (b) Release of glucose
Thus (b) is correct option. (c) Uptake of carbon dioxide and release of
oxygen
18. Where does the light reaction of photosynthesis (d) Absorption of chlorophyll
take place?
Ans : COMP 2015
(a) Stroma
(b) Cytoplasm Photorespiration occurs when oxygen is taken
(c) Thylakoids up, and carbon dioxide is released, usually in the
(d) Nucleus light.
Thus, (a) is the correct option.
Ans : MAIN 2012

The light reaction of photosynthesis occurs in the 23. Which pigment is responsible for the green color
thylakoids of the chloroplast where light energy in leaves and absorbs light for photosynthesis?
is absorbed by chlorophyll and converted into (a) Carotenoids
chemical energy. (b) Chlorophyll
Thus, (c) is the correct option. (c) Xanthophylls
(d) Anthocyanins
19. What are the end products of the light reaction
Ans : SQP 2011
in photosynthesis?
(a) Oxygen and ATP Chlorophyll is the green pigment that absorbs
(b) Oxygen, ATP, and NADPH light energy for photosynthesis.
(c) Carbon dioxide and water Thus, (b) is the correct option.
(d) Glucose and ATP
24. In which phase of photosynthesis is carbon dioxide
Ans : COMP 2008 fixed into glucose?
During the light reaction, water is split to produce (a) Light reaction
oxygen, and ATP and NADPH are generated to (b) Dark reaction
be used in the dark reaction. (c) Photolysis
Thus, (b) is the correct option. (d) Photorespiration
Ans : MAIN 2007
CH 5 : PHOTOSYNTHESIS

45. The teacher asked students to name two organs in Ans : COMP 2008

the human respiratory system. Insulin lowers blood sugar by converting glucose
Raj said: Lungs and Diaphragm into glycogen, and adrenaline is known for
Sonu said: Lungs and Kidney increasing heart rate and boosting energy.
Lata said: Trachea and Alveoli Thus, (b) is the correct option.
Abhay said: Heart and Lungs
Who were correct? 48. Anita matched the hormones with their roles in
(a) Raj and Lata the body. The table below shows her result:
(b) Sonu and Abhay Effect on the body
Hormone
(c) Lata and Abhay
(d) Raj and Sonu Promotes water reabsorption in
P
kidneys
Ans : SQP 2009
Regulates growth and development
The lungs, diaphragm, trachea, and alveoli are Q
of bones
part of the respiratory system, while the kidneys
and heart are not. Raj and Lata are correct. Identify the correct pair of hormones:
Thus, (a) is the correct option. (a) P – Adrenaline, Q – Glucagon
(b) P – Vasopressin, Q – Growth Hormone
46. A teacher asked students to give two examples of (c) P – Insulin, Q – Adrenaline
elements. (d) P – Oxytocin, Q – Adrenaline
Raj said: Gold and Oxygen Ans : SQP 2002
Sonu said: Hydrogen and Carbon Dioxide
Lata said: Nitrogen and Silver Vasopressin promotes water reabsorption in
Abhay said: Carbon and Water the kidneys, and growth hormone regulates the
Who were correct? growth and development of bones.
(a) Raj and Lata Thus, (b) is the correct option.
(b) Sonu and Abhay
49. Sam matched the hormones with their functions
(c) Raj and Sonu
as follows:
(d) Lata and Abhay
Ans : MAIN 2004
Hormone Effect on the body

Gold, oxygen, hydrogen, nitrogen, silver, and Stimulates milk production in

P
carbon are elements, while carbon dioxide and mammals
water are compounds. Therefore, Raj and Lata Q Raises blood calcium levels
are correct. Identify the correct pair of hormones:
Thus (a) is the correct option. (a) P – Prolactin, Q – Parathyroid Hormone
(b) P – Adrenaline, Q – Thyroxine
DIRECTION : Matching Type Question (c) P – Glucagon, Q – Vasopressin
(d) P – Vasopressin, Q – Oxytocin
47. Ravi tried to match the hormones with their
effects on the human body. He tabulated the pairs Ans : MAIN 2020

as follows: Prolactin stimulates milk production in mammals,

and parathyroid hormone raises blood calcium
Hormone Effect on the body levels.
P Lowers blood sugar by converting Thus, (a) is the correct option.
glucose into glycogen
50. Vikram matched the following hormones with
Q Increases heart rate and boosts their roles:
energy
Identify the correct pair of hormones: Hormone Effect on the body
(a) P – Insulin, Q – Glucagon P Stimulates the release of insulin
(b) P – Insulin, Q – Adrenaline
Q Increases the production of red
(c) P – Glucagon, Q – Vasopressin
blood cells
(d) P – Oxytocin, Q – Adrenaline
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 159

Hydrilla and Elodia are aquatic plants used in occurred.

experiments to demonstrate oxygen evolution Thus, (b) is the correct option.
during photosynthesis.
Thus, (b) is the correct option.
DIRECTION : Case Base Question
34. Which pigment breaks down first in leaves before
leaf fall, revealing carotenoids? 38. The diagram given below represents an
(a) Chlorophyll experiment to demonstrate a particular aspect of
(b) Xanthophyll Photosynthesis. The letter ‘A’ indicates a certain
(c) Anthocyanin condition inside the flask. Answer the questions :
(d) Carotene
Ans : COMP 2012

Chlorophyll breaks down first in leaves before

leaf fall, revealing the yellow and red pigments of
carotenoids.
Thus, (a) is the correct option.

35. What happens to carbohydrates formed during

photosynthesis?
(a) They are released as oxygen.
(b) They are used in respiration, storage, and
growth. (i) What is the aim of the experiment ?
(c) They are converted to nitrogen compounds. (a) To show that oxygen is released during
(d) They are absorbed by roots. Photosynthesis.
Ans : SQP 2008 (b) To show that Photosynthesis occurs in
the presence of KOH.
Carbohydrates produced during photosynthesis
(c) To show that chlorophyll is necessary for
are used for respiration, stored for later use, or
Photosynthesis.
used for growth.
Thus, (b) is the correct option. (d) To show that carbon dioxide is necessary
for Photosynthesis.
36. What are the primary products formed in the
Ans : MAIN 2021
light reaction of photosynthesis?
(a) ATP and oxygen Thus (d) is correct option.
(b) ATP and NADPH (ii) What is the special condition inside the flask?
(c) Carbon dioxide and glucose (a) Air inside the flask is free of oxygen.
(d) ADP and oxygen
(b) Air inside the flask is free of carbon
Ans : MAIN 2004 dioxide.
The light reactions produce ATP and NADPH, (c) Air inside the flask is free of nitrogen.
which are used in the Calvin cycle to fix carbon (d) KOH purifies the air inside the flask.
dioxide into glucose.
Ans : MAIN 2021
Thus, (b) is the correct option.
Thus (b) is correct option.
37. What solution is used to test for the presence of
starch in leaves? (iii) An alternative chemical that can be used
(a) Methylated spirit instead of KOH is :
(b) Iodine (a) Sodium hydroxide.
(c) Benedict’s solution (b) Sodium chloride.
(d) Hydrochloric acid (c) Potassium chloride.
(d) Potassium permanganate.
Ans : COMP 2011
Ans : MAIN 2021
Iodine solution turns blue-black in the presence
of starch, indicating that photosynthesis has Thus (a) is correct option.
CH 5 : PHOTOSYNTHESIS

It is because the snail can provide carbon dioxide is named after him, which refers to the light-
for photosynthesis and it has got all requirements dependent reactions of photosynthesis.
for its survival. Thus (d) is correct option.
Thus (e) is correct option.
12. What is the functional unit of chloroplasts capable
8. What is the main function of photosynthesis? of absorbing light?
(a) To produce oxygen (a) Stroma
(b) To transduce light energy into chemical (b) Thylakoid
energy (c) Quantasome
(c) To consume water and release carbon dioxide (d) Granum
(d) To break down chlorophyll
Ans : MAIN 2002
Ans : SQP 2018
Quantasomes are small spherical structures on
Photosynthesis is the process where light energy the thylakoid membrane that absorb light and
is converted into chemical energy in the form of are the functional units of chloroplasts involved
carbohydrates, which serve as food for plants and, in photosynthesis.
indirectly, for other organisms. Thus (c) is correct option.
Thus (b) is correct option.
13. What pigment group primarily absorbs light for
9. Where does the majority of photosynthesis occur photosynthesis?
on Earth? (a) Chlorophylls
(a) In forests (b) Carotenes
(b) In deserts (c) Xanthophylls
(c) In oceans (d) Anthocyanins
(d) In mountains
Ans : COMP 2017
Ans : MAIN 2014
Chlorophylls are the main pigments involved
Up to 90% of photosynthesis on Earth takes place in absorbing light energy, which is then used in
in the oceans, mainly through phytoplankton and photosynthesis to produce carbohydrates.
other aquatic plants. Thus (a) is correct option.
Thus (c) is correct option.
14. Which pigment is responsible for the green color
10. What is the site of the light reaction of of plants?
photosynthesis? (a) Chlorophyll
(a) Stroma (b) Carotene
(b) Thylakoid (c) Xanthophyll
(c) Grana (d) Anthocyanin
(d) Quantasome
Ans : SQP 2013
Ans : COMP 2010
Chlorophyll reflects green light, which gives plants
Grana are stacks of thylakoids in the chloroplasts their green color and is crucial for photosynthesis.
where the light-dependent reactions of Thus (a) is correct option.
photosynthesis occur.
Thus (d) is correct option. 15. Which of the following is NOT a requirement for
photosynthesis?
11. Who discovered chloroplasts as the site of (a) Chlorophyll
photosynthesis? (b) Oxygen
(a) Robert Brown (c) Water
(b) Robert Hill (d) Carbon dioxide
(c) Joseph Priestley
Ans : MAIN 2009
(d) Julius von Sachs
Oxygen is a byproduct of photosynthesis, not a
Ans : SQP 2006
requirement. The essential requirements are light,
Robert Hill discovered that the chloroplast is the water, carbon dioxide, and chlorophyll.
site of photosynthesis, and the "Hill reaction" Thus (b) is correct option.
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MATHEMATICS PHSYSICS CHEMISTRY BIOLOGY

Class 10 Class 10 Class 10 Class 10

NODIA ICSE NODIA ICSE NODIA ICSE NODIA ICSE

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HISTORY COMPUTER
GEOGRAPHY HINDI
& APPLICATION
Class 10 CIVICS Class 10 Class 10
Class 10

NODIA ICSE NODIA ICSE NODIA ICSE NODIA ICSE

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ENGLISH LITERATURE COMMERICAL

LANGUAGE IN ECONOMICS STUDIES
Class 10
ENGLISH Class 10 Class 10
Class 10

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94142 43489
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 161

(v) If some sodium bicarbonate is added to the DIRECTION : Conversation Type Question
water, the rate of bubble formation :
(a) increases because more respiration occurs. 42. A biology teacher asked her students to identify
(b) increases because more photosynthesis two examples of mammals.
occurs. Raj said: Cat and Dog
(c) increases because the gas becomes less Sonu said: Frog and Whale
soluble. Lata said: Bat and Elephant
(d) decreases because carbon dioxide acts as Abhay said: Eagle and Dolphin
a limiting factor. Who were correct?
(e) decreases because respiration decreases. (a) Abhay and Sonu
Ans : SQP 2020
(b) Raj and Lata
(c) Sonu and Lata
Thus (b) is correct option. (d) Raj and Abhay
40. A plant physiologist is investigating the effects Ans : SQP 2010
of de-starching on a plant. The plant is treated Cats, dogs, bats, and elephants are all mammals.
to remove stored starch from certain parts before Frogs are amphibians, and eagles are birds, so
conducting experiments on photosynthesis. A de- Sonu and Abhay are incorrect.
starched plant is one whose: Thus, (b) is the correct option.
(a) leaves are free from chlorophyll
(b) aerial parts are free from starch 43. The teacher asked students to give two examples
(c) leaves are free from starch of amphibians.
Raj said: Frog and Salamander
(d) plant is free from starch.
Sonu said: Turtle and Toad
Ans : MAIN 2012 Lata said: Frog and Toad
In the process of de-starching, a plant is placed Abhay said: Salamander and Crocodile
in the dark for 24 to 48 hours, which allows the Who were correct?
plant to utilize its stored starch reserves. This (a) Lata and Raj
ensures that the plant's leaves are free from (b) Raj and Abhay
starch, making it ideal for experiments involving (c) Sonu and Lata
photosynthesis. De-starching does not involve the (d) Raj and Sonu
removal of chlorophyll or starch from all parts of Ans : MAIN 2006
the plant; rather, it specifically removes starch Explanation: Frogs, toads, and salamanders are
from the leaves where photosynthesis occurs. amphibians, while turtles and crocodiles are
Thus (c) is correct option. reptiles, making Lata and Raj correct.
41. A plant is kept in a dark cupboard for about Thus, (a) is the correct option.
48 hours before conducting an experiment on 44. The teacher asked her class for two examples of
photosynthesis to: plants that perform photosynthesis.
(a) Remove starch from the plant. Raj said: Cactus and Mushroom
(b) Ensure that starch is not translocated from Sonu said: Fern and Pine
the leaves. Lata said: Rose and Cactus
(c) Remove chlorophyll from the leaf of the plant. Abhay said: Mushroom and Fern
(d) Remove starch from the experimental leaf. Who were correct?
(a) Raj and Abhay (b) Sonu and Lata
Ans : SQP 2016
(c) Raj and Sonu (d) Lata and Sonu
Keeping a plant in the dark for 48 hours depletes Ans : COMP 2002
the starch in its leaves, ensuring they are starch-
free for the experiment. This step helps confirm Mushrooms do not perform photosynthesis
whether starch is produced during photosynthesis because they are fungi, while plants like ferns,
in the experiment. pine, roses, and cacti do. Therefore, Sonu and
Thus (d) is correct option. Lata are correct.
Thus, (b) is the correct option.
CH 5 : PHOTOSYNTHESIS

(iv) In what manner do the leaves 1 and 2 differ

at the end of the starch test ?
(a) Leaf 1 turns brown, Leaf 2 turns blue
black.
(b) Leaf 1 turns blue black, Leaf 2 turns
brown.
(c) Leaf 1 turns purple, Leaf 2 remains green.
(d) There is no change in the colour of the
leaves.
Ans : MAIN 2021

Thus (a) is correct option.

(v) What is the important step that should be
taken before performing this experiment ?
(a) The plant should be placed in dark for 24
hours to destarch the entire plant.
(b) The plant should be placed in dark for
24 hours to remove chlorophyll from the (i) From the graph it seems likely that the rate
leaves. of bubbling per minute at 50 cm would have
(c) The plant should be placed in dark for 24 been:
hours to destarch the leaves. (a) 2.0 (b) 2.5
(d) The plant should be placed in dark for 24 (c) 3.0 (d) 3.5
hours for the roots to absorb water. (e) 4.0

Ans : MAIN 2021

Ans : SQP 2020

Thus (c) is correct option. Thus (d) is correct option.

(ii) The gas produced by the plant during the
39. The diagram refers to an experiment in which experiment was :
the apparatus was set up with the light source (a) air (b) oxygen
kept away from the plant. After 15 minutes the (c) carbon dioxide (d) nitrogen
number of bubbles evolved per minute from the (e) hydrogen
cut stem was recorded. The light source was
moved to 20 cm away from the plant, left for 15 Ans : SQP 2020

minutes and the number of bubbles evolved per Thus (b) is correct option.
minute was again recorded. The experiment was (iii) The gas collected comes due to the breakdown
again recorded. The experiment was repeated of :
with the light source at distance of 40, 60, 80, (a) glucose (b) starch
100 cm away from the plant. The results obtained (c) water (d) air
were recorded on the graph : Select the correct (e) ATP.
answer out of the available choice given under
each question : Ans : SQP 2020

Thus (c) is correct option.

(iv) If ice cubes were added to the water, the rate
of bubble formation would :
(a) stay the same.
(b) increase because more water is added.
(c) decrease because the temperature drops.
(d) decrease because water freezes.
(e) cannot tell from the information given.
Ans : SQP 2020

Thus (c) is correct option.

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 163

Identify the correct pair of hormones: 56. The process of conversion of ADP into ATP
(a) P – Glucagon, Q – Erythropoietin during photosynthesis.
(b) P – Oxytocin, Q – Vasopressin
Ans : SQP 2011
(c) P – Insulin, Q – Parathyroid Hormone
(d) P – Adrenaline, Q – Glucagon Photophosphorylation

Ans : COMP 2016 57. The site of dark reaction of photosynthesis.

Glucagon stimulates the release of insulin by Ans : COMP 2021
breaking down glycogen, and erythropoietin
Stroma
increases the production of red blood cells.
Thus, (a) is the correct option. 58. The organisms which convert complex organic
matter into simple ones.
51. Neha matched the hormones with their effects as
shown below: Ans : MAIN 2023

Hormone Effect on the body Decomposers

P Promotes the release of glucose into 59. The only biological process that releases oxygen
the bloodstream into the air.
Q Controls the body’s metabolism rate Ans : SQP 2019

Identify the correct pair of hormones: Photosynthesis

(a) P – Glucagon, Q – Thyroxine
(b) P – Vasopressin, Q – Oxytocin 60. The food produced by green plants.
(c) P – Glucagon, Q – Vasopressin Ans : MAIN 2005
(d) P – Insulin, Q – Thyroxine
Glucose
Ans : SQP 2012
61. The cell organelle/principle site responsible for
Glucagon promotes the release of glucose into the
photosynthesis.
bloodstream, and thyroxine controls the body’s
metabolism rate. Ans : COMP 2000

Thus, (a) is the correct option. Chloroplast

62. The ground substance present in a chloroplast.

DIRECTION : Name the following :
Ans : MAIN 2008
52. The structure where photophosphorylation takes
Stroma
place.
Ans : MAIN 2005 63. The chemical used to test starch.
Thylakoid/grana Ans : SQP 2010

Iodine
53. The part of the chloroplast where the light
reaction of photosynthesis takes place. 64. The process by which green plants prepare their
Ans : COMP 2011 own food.
Grana Ans : SQP 2017

Photosynthesis
54. Plants that prepare their own food from basic raw
materials. 65. The products of photosynthesis.
Ans : SQP 1999 Ans : MAIN 2020

Autotrophs Glucose, water and oxygen

55. The cell organelle responsible for photosynthesis. 66. A plant that does not perform photosynthesis.
Ans : MAIN 2009 Ans : COMP 2023

Chloroplast Mushroom/Fungus
CH 5 : PHOTOSYNTHESIS

143. Photosynthesis stops to occur at temperature from the leaves of plant.

above 40°C.
153. The splitting of water molecules into hydrogen
Ans : COMP 2018
and hydroxyl ions is termed photolysis.
True. Ans : MAIN 2005

144. Starting point of a food chain is a plant. The splitting of water molecules into hydrogen
and hydroxyl ions by light is termed photolysis.
Ans : MAIN 2009

True.
DIRECTION : Correct the following statement by
145. Photosynthesis takes place in chromoplast. changing the underlined word :
Ans : SQP 2013
154. Xylem transports starch from the leaves to all
False. Photosynthesis takes place in chloroplast. parts of the plant body.
146. Biosynthetic phase needs no light. Ans : SQP 2018

Ans : COMP 2010 Phloem

True. 155. The solvent used to dissolve the chlorophyll
pigments while testing a leaf for starch is Soda
147. Plants produce starch as food.
lime.
Ans : COMP 2002
Ans : MAIN 2017
False. Plants produce glucose as food.
The solvent used to dissolve the chlorophyll
148. Consumers are also called as heterotrophs. pigments while testing a leaf for starch is
Methylated spirit/Alcohol
Ans : MAIN 2000

True.
DIRECTION : Give biological reasons :
149. Photosynthesis needs an optimum temperature.
156. A tiger owes its existence to chlorophyll.
Ans : SQP 2005
Ans : COMP 2004
True.
Green plants synthesise food by photosynthesis
150. Food is translocated by xylem. using chlorophyll. Tiger feeds on animal which
Ans : COMP 2013
feed on green plants thus they obtain their food
indirectly from green plants.
False. Food is translocated by phloem.
157. Photosynthesis is considered as a process
151. Plants that manufacture their own food are called supporting all life on earth.
heterotrophs.
Ans : SQP 2011
Ans : MAIN 2020
Green plants synthesise food by photosynthesis
False. Plants that manufacture their own food are using chlorophyll. Carnivores feed on animals
called autotrophs. which feed on green plants thus they obtain their
food directly or indirectly by photosynthesis.
DIRECTION : Rewrite the correct form of statement
158. All the food chains begin with green plants.
by inserting a suitable word/words at right place. Do
not delete any word in the statement : Ans : MAIN 2018

All food chains begin with green plants as they

152. Destarching a plant means removing the starch manufacture food for all living organisms by
from the plant. photosynthesis.
Ans : COMP 2005
159. All life on Earth is supported by Photosynthesis.
Destarching the plant means removing the starch
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 165
Ans : MAIN 2011
Chloroplasts
Green
98. The splitting of water molecules by photons is
88. The chemical used to test starch. called______.
Ans : COMP 2008 Ans : MAIN 2009

Iodine photolysis

89. The type of leaf which is used to demonstrate 99. In photosynthesis, ______is reduced and
that chlorophyll is necessary for photosynthesis. ______is oxidised.
Ans : SQP 2001 Ans : SQP 2017

Variegated leaf CO2, water

90. The plastids found in cells of yellow coloured 100. In photosynthesis, radiant energy is converted
petals. into______.
Ans : MAIN 2003 Ans : MAIN 2001

Chromoplast chemical energy

Sunlight
91. The ground substance present in chloroplast. 101. ______+ 12H2O Chlorophyll C6H12O6
+______+______.
Ans : COMP 2012

Stroma/Matrix Ans : SQP 2012

Sunlight
6CO2 + 12H2O Chlorophyll C6H12O6 + 6H2O + 6O2
DIRECTION : Complete the following: 102. Calvin cycle was proposed by______.

92. Splitting of water results in the release Ans : COMP 2015

of______. Melvin Calvin

Ans : MAIN 2011 103. ______is the process which replenishes
oxygen the atmospheric oxygen which the animal life
consumes in respiration.
93. Starch can be tested by______
Ans : MAIN 2008
Ans : SQP 2015
Photosynthesis
iodine
104. Light reaction of photosynthesis takes place
94. Xanthophyll is______coloured pigment. in______.
Ans : SQP 2020 Ans : SQP 2013

yellow grana of chloroplasts

95. Carbon dioxide enters the leaf through______. 105. ATP stands for______.
Ans : MAIN 2012 Ans : MAIN 2010

stomata Adenosine triphosphate

96. Dark reaction takes place in the______of the 106. The light independent reactions of photosynthesis
chloroplast. are also known as______phase.
Ans : COMP 2000 Ans : SQP 2007

stroma of chloroplast Biosynthetic

97. ______are regarded as complete photosynthetic 107. Chlorophyll is present in the______of
units of plants. chloroplasts.
Ans : SQP 2004 Ans : COMP 2023
CH 5 : PHOTOSYNTHESIS

67. A gas released by green plants during Green plants

photosynthesis.
78. The process of conversion of complex organic
Ans : SQP 2018
matter into simple forms by microorganisms.
Oxygen Ans : COMP 2006

68. The raw materials needed for photosynthesis. Decay

Ans : MAIN 2005
79. The immediate product of photosynthesis.
Carbon dioxide and water. Ans : MAIN 2003

69. The reaction by which the water molecules are Glucose

broken down by means of light.
80. Damage of photosynthetic apparatus at very high
Ans : COMP 2008
temperature.
Photolysis Ans : COMP 2019

70. The first stable product formed during CO2 Solarization

fixation.
81. Any two plants which do not perform
Ans : MAIN 2013
photosynthesis.
Phosphoglyceric Acid (PGA) Ans : SQP 2014

71. The experiment to demonstrate the importance of Cuscuta ; Mushroom

light for photosynthesis.
82. The part of chloroplast where light reaction
Ans : SQP 2002
occurs.
Light screen experiment Ans : MAIN 2022

72. The energy currency of the cell. Grana

Ans : SQP 2000
83. The chemical reaction in which oxygen is given
ATP out.

73. The substance from which oxygen is evolved Ans : MAIN 2016

during photosynthesis. Photolysis of water

Ans : MAIN 2009
84. Organelles that transform radiant energy in to
Water the molecules of organic compounds.

74. The organisms which can prepare their own food. Ans : COMP 2012

Chloroplasts
Ans : MAIN 2016

Autotrophs 85. The chemical that absorbs carbon dioxide during

dark raction.
75. The substance which capture photons in plants.
Ans : MAIN 2010
Ans : SQP 2022
Ribulose bi phosphate
Chlorophyll
86. The colour or rays in which the rate of
76. The organisms which convert complex organic photosynthesis is highest next to red.
matter into simple forms.
Ans : SQP 2019
Ans : MAIN 2014
Blue
Decomposers
87. The colour in which the rate of photosynthesis is
77. The starting point of all food chains. minimum.
Ans : COMP 2018
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 167
Ans : COMP 1999
134. The solvent used to dissolve the chlorophyll
False pigments while testing a leaf for starch is Soda
lime.
125. The unit of light absorbed by the chlorophyll
during photosynthesis is the proton. Ans : MAIN 2007

False. The solvent used to dissolve the chlorophyll

Ans : MAIN 1997
pigments while testing a leaf for starch is
False methylated spirit/methyl alcohol.
126. Photosynthesis stops to occur at a temperature 135. The dark reaction of photosynthesis is light
above 35°C. independent.
Ans : COMP 2004 Ans : SQP 2016

False True.
127. Photosynthesis occurs in all the cells of the plant. 136. Land plants obtain their carbon dioxide from the
Ans : SQP 2009 atmosphere.
False Ans : COMP 2023

True.
128. Photolysis is the process of splitting of
water molecules in the presence of grana and 137. In a typical leaf, photosynthesis occurs mainly in
temperature. spongy mesophyll.
Ans : MAIN 2010 Ans : SQP 2021

False. Photolysis is the process of splitting of False. In a typical leaf, photosynthesis occurs
water molecules in the presence of grana and light. mainly in palisade cells.
129. The ultimate electron donor in photosynthesis is 138. Photosynthesis occurs in all plants.
water.
Ans : MAIN 2010
Ans : COMP 2022
False. Respiration occurs in all plants.
True
139. Oxygen is necessary for photosynthesis.
130. Light dependent reactions of photosynthesis occur
in stroma of chloroplast. Ans : SQP 2014

False. Carbon dioxide is necessary for

Ans : SQP 2017
photosynthesis.
False
140. Plants can be destarched by keeping in dark for
131. Plants can be destarched by keeping in dark for 48 hours.
10 hours.
Ans : MAIN 2020
Ans : COMP 2014
True.
False
141. Carbon dioxide is a life supporting gas produced
132. In a leaf photosynthesis occurs mainly in spongy during photosynthesis.
mesophyll.
Ans : MAIN 2022
Ans : MAIN 2000
False. Oxygen is a life supporting gas produced
False during photosynthesis.
133. Photosynthesis stops to occur at temperature 142. KOH absorbs carbon dioxide.
above 35 degree centigrade.
Ans : SQP 2015
Ans : COMP 2005
True.
True.
CH 5 : PHOTOSYNTHESIS

Thylakoids This product is converted to starch. The process

is called (10)______.
108. The smaller unit of light energy is______
Ans : COMP 2007
Ans : MAIN 2020
(1) leaves (2) water
Photons (3) hydrogen ion (4) photolysis.
(5) hydrogen (6) NADPH2.
109. In photophosphorylation, a energy is needed to
(7) ATP. (8) photophosphorylation.
add phosphate to______
(9) glucose. (10) polymerisation.
Ans : SQP 2011

ADP DIRECTION : Give exact location and function :

110. ______stores energy in a cell.
117. Thylakoids
Ans : COMP 2014
Ans : SQP 2005
ATP
Granum of chloroplast. Help in trapping sunlight
111. The thinness of leaf______photosynthesis. (photosynthesis).
Ans : SQP 2016 118. Grana
increases Ans : MAIN 1999

112. The stored form of glucose is______. Inside chloroplast. Help in trapping sunlight.
Ans : SQP 2002 119. Guard cell
starch Ans : COMP 2001

113. Light energy is trapped by______. Around stomata mostly under the surface of a
dorsiventral leaf. Allow diffusion of gases.
Ans : MAIN 2018

chlorophyll 120. Stoma

Ans : COMP 2006
114. ______and______are formed during
photolysis. Epidermis of leaves. Exchange of gases for
photosynthesis/respiration/loss of water as water
Ans : COMP 2003
vapour during transpiration.
H+, (OH) -

115. ______colour forms when iodine is added to DIRECTION : State true or false
starch.
121. Photosynthesis occurs in all the cells of a plant.
Ans : SQP 2021
Ans : MAIN 2005
Blue-black
False
116. Photosynthesis involves light reaction and dark
reaction. During light reaction, the chlorophyll 122. Stomata is stimulated by light.
present in the (1)_____gets activated by Ans : COMP 2002
absorbing light energy. This energy splits
(2)______molecules to (3)______and True
oxygen and releases two electrons. This process 123. Grana helps in diffusion of gases.
is called (4)______. The (5)______ions are
picked up by NADP to form (6)______. The Ans : MAIN 2007

ADP is converted to (7)______. This process False

is called (8)______. During the dark phase, the
compound produced at the end of light reaction 124. Photosynthesis results in the loss of dry weight of
reacts with carbon dioxide to form (9)______. the plant.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 169
Ans : SQP 2019
166. Which one of these reaction occurs during
Provides oxygen for respiration. Provides food photosynthesis ? (carbon dioxide is reduced and
and maintains food chain. water is oxidized, water is reduced and carbon
dioxide is oxidized, carbon dioxide and water
160. Complete the following process to show how the both are oxidized, carbon dioxide and water both
oxygen in the air reaches a mesophyll cell of the are reduced ).
leaf.
Oxygen in air $ --- $ --- $ Ans : SQP 1998

Mesophyll cell. Carbon dioxide is reduced and water is oxidized.

Ans : COMP 2004
167. A destarched plant is one whose (leaves are free
Stoma, substomatal space. from chlorophyll, aerial parts are free from starch,
leaves are free from starch, plant is free from
starch).
DIRECTION : Choose the correct alternative :
Ans : COMP 2009

161. A plant is kept in a dark cupboard for about Leaves are free from starch.
48 hours before conducting any experiment on
168. Which of the following lights are the most
photosynthesis to (remove chlorophyll from
effective for photosynthesis ? (green, yellow, blue,
leaves, remove starch from the plant, ensure that
red, yellow and violet).
no photosynthesis occurs, ensure that leaves are
free from starch.) Ans : MAIN 2019

Ans : MAIN 2002 Blue and red

Ensure that leaves are free from starch. 169. Sunlight arrives at a plant in units of light energy
called (protons, photons, electrons, wavelengths).
162. The site of light reaction in the cells of a leaf is
(grana, cytoplasm, stroma). Ans : SQP 2012

Ans : SQP 2001 Photons

Grana. 170. Which of the following is not a useful function
of the light reaction in photosynthesis? (Splitting
163. The chemical substance used to test the presence
water, Synthesis of NADPH, Converting light
of starch in the cell of a leaf is (cobalt chloride
energy into chemical energy, Releasing oxygen for
paper, iodine solution, Benedict’s solution).
photorespiration).
Ans : MAIN 2001
Ans : COMP 2022
Iodine solution.
Releasing oxygen for photorespiration
164. The specific function of light energy in the
171. The conversion of ADP into ATP in presence of
process of photosynthesis is to (reduce carbon
light.
dioxide, synthesise glucose, activate chlorophyll,
split water). Ans : SQP 2017

Ans : COMP 2000 Photophosphorylation

Activate chlorophyll. 172. The raw material for photosynthesis which gets
reduced.
165. If the rate of respiration becomes more than
the rate of photosynthesis plants will (continue Ans : MAIN 2012
to live but will not be able to store food, be Carbon dioxide
killed instantly, grow more vigorously because
more energy will be available, stop growing and 173. The electron acceptor in light reaction of
gradually die of starvation). photosynthesis.
Ans : MAIN 1998 Ans : SQP 2016

Stop growing and gradually die of starvation. Nicotinamide adenine dinucleotide phosphate
CH 5 : PHOTOSYNTHESIS
Ans : SQP 2017 Ans : MAIN 2009

Green plants manufacture food during the process It means conversion of ATP from ADP and
of photosynthesis and give out oxygen which is a inorganic phosphate in the presence of light.
life supporting gas for all organisms. Therefore, All food chains start with green plants.
green plants are essential for life.
240. Heterotrophs
233. ATP is needed for dark reaction.
Ans : COMP 2006
Ans : MAIN 2001
The organisms which depend on autotrophs for
ATP provides energy for dark reaction. The their food are heterotrophs. They do not have
energy is required to make glucose that is formed chlorophyll. e.g. Man.
through a series of reactions in Calvin cycle.

234. Respiration is said to be the reversal of DIRECTION : State the function of the following:
photosynthesis.
241. Stomata
Ans : COMP 2019
Ans : SQP 2001
Respiration is a catabolic process while
photosynthesis is an anabolic process. During Exchange of gases, transpiration
respiration, O2 is taken in and CO2 is given out
242. Light energy
while during photosynthesis CO2 is taken in and
O2 is given out. Ans : MAIN 2007

To split water molecule into H+ and (OH) ions.

-
235. Dark reaction is called biosynthetic phase.
Ans : SQP 2003 243. Potassium hydroxide
Light is not required in dark reaction but occurs Ans : SQP 2000
simultaneously with light reaction. In this glucose To absorb CO2.
is produced by a number of steps using certain
enzymes. So, dark reaction is called biosynthetic 244. Chlorophyll
phase.
Ans : COMP 2004

236. Stroma To absorb sunlight.

Ans : MAIN 2010
245. Thylakoid
The ground matter present in the chloroplast
Ans : COMP 2013
is the stroma. Thylakoids are arranged in the
stroma. Site of photosynthesis.

237. Autotrophs DIRECTION : Choose the correct options from the

Ans : SQP 2022 brackets and complete.

The dark reaction of photosynthesis take place

246. During photosynthesis, solar energy is converted
in it.
into______.[Heat, Chemical, Mechanical,
238. Food chain Electrical]

Ans : COMP 2015 Ans : SQP 2000

The inter-dependence of food by various chemical energy.

organisms, or the energy flow from one organism
247. Function of light energy in photosynthesis.
to another is called food chain.
[Splitting of water molecule into H+ and OH–,
For example: Grass $ Insect $ Frog $
reduce CO2, activate chlorophyll, formation of
Snake $ Peacock.
glucose molecules]
All food chains start with green plants.
Ans : SQP 2007
239. Photophosphorylation
To activate chlorophyll
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 171

185. Define photophosphorylation. NADP : Nicotenamide Adenine Dinucleotide

Phosphate
Ans : MAIN 2002
ATP : Adenosine triphosphate
Conversion of low grade energy ADP into high
potential chemical energy ATP. 193. Differentiate between the following pairs on the
basis of what is indicated in the brackets.
186. What is meant by photolysis of water ? (i) Leaf and Liver [form in which glucose is
Ans : COMP 1997 stored]
(ii) ATP and AIDS [expand the abbreviations]
Splitting of water into hydrogen and hydroxyl ion
in presence of sunlight. Ans : MAIN 2018

(i) Leaf – Starch

187. Write the full form of NADP and ATP.
Liver – Glycogen
Ans : MAIN 2004, 2002 (ii) ATP – Adenosine triphosphate
NADP- Nicotinamide adenine dinucleotide AIDS – Acquired Immuno Deficiency
phosphate. Syndrome
ATP - Adenosine tri phosphate.
194. Why is sleeping under a tree at night not
188. Expand the abbreviation NADP. advisable?

Ans : SQP 2013 Ans : COMP 2022

Nicotinamide Adenine Dinucleotide Phosphate At night, the atmosphere surrounding the tree is
rich in CO2 which is harmful, since photosynthesis
189. State the exact location of the Chloroplast. does not take place at night and only respiration
occurs. So, sleeping under a tree at night is not
Ans : MAIN 2013
advisable.
Mesophyll cells/Palisade and Spongy cells of
leaves. 195. Expand the following biological abbreviation :
ATP
190. Photolysis and Photophosphorylation.
Ans : MAIN 2019
Ans : COMP 2005
Adenosine triphosphate
The difference between Photolysis and
Photophosphorylation are as follows : 196. Mention the exact location of the following :
Thylakoids
Photolysis Photophosphorylation
Ans : SQP 2019, 2015
Splitting of water Production of ATP
molecules into H+ and molecule from ADP by In the stroma (matrix) of chloroplast
OH+ ions with the help adding one phosphate 197. Mention any three adaptations found in plants to
of light energy. group iP (inorganic favour the process of photosynthesis.
phosphate) with the
help of energy that Ans : COMP 2011

comes from light. (a) Large surface area of the leaves.

(b) Presence of more stomata.
191. Briefly explain the term photophosphorylation. (c) The thinness of leaves.
Ans : MAIN 2016
198. State the conditions needed for photosynthesis.
Photophosphorylation is the synthesis of ATP from Ans : MAIN 2006
ADP and phosphate that occurs in a plant using
radiant energy absorbed during photosynthesis. The conditions needed for photosynthesis are:
(a) Presence of sunlight.
192. Differentiate between the following pair on the (b) Concentration of carbon dioxide.
basis of what is mentioned in bracket : (c) Temperature.
NADP and ATP [Expand the abbreviation] (d) Water content.
Ans : SQP 2017
CH 5 : PHOTOSYNTHESIS

free as during this period whole of the starch Light Reaction Dark Reaction
present in the leaves will be used. It ensures
any starch present after the experiment has (i) It takes place in (i) It does not
been formed under experimental conditions. the presence of require light.
light.
280. Mention any three adaptations found in plants to (ii) It occurs in (ii) It occurs in
favour the process of photosynthesis. the grana of the stroma of
Ans : MAIN 2009 chloroplast. chloroplast.
Three adaptations found in plants to favour the (iii) Its products (iii) Its products
process of photosynthesis are : are ATP and are organic
(1) Large surface area of the leaves. NADPH. compounds.
(2) Leaf arrangement (maximum surface area
exposed to light). 284. The diagram shows how carbon compounds are
(3) Numerous stomata on the leaves. recycled.

281. Mention any three points in which respiration is

exactly opposite of photosynthesis.
Ans : SQP 1995

Respiration Photosynthesis
(i) It is catabolic It is an anabolic
process in which process in which
food substances are food substances are
broken down. synthesized.

(ii) It uses oxygen to It uses carbon

oxidize the food dioxide and water
substances and to synthesize the
releases carbon food and releases (i) Name the processes shown by the arrows B,
dioxide and energy. oxygen. C, D and E.
(ii) Name a type of organism you expect to be
(iii) It occurs at all It occurs only in named in box A.
times of day and the day in presence
Ans : SQP 2003
night. of light.
(i) B is a decay; C is respiration; D is respiration
and E is photosynthesis.
282. Draw a simplified diagram of a chloroplast. (ii) Bacteria/fungi
Ans : MAIN 2002
285. Distinguish between Producers and Consumers.
Ans : COMP 2022

Producers Consumers
(i) They are called (i) They are called
as autotrophs. as heterotrophs.

(ii) They can make (ii) They cannot

their own food. make their own
food.
283. Distinguish between Light and Dark reaction. (iii) The cells contain (iii) Chlorophyll is
chlorophyll. absent in cells.
Ans : SQP 2017
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 173

215. State the internal factors which affect reaction).

photosynthesis.
225. Oxygen is a waste product of photosynthesis.
Ans : MAIN 2001
Justify.
Chlorophyll content, anatomy of the leaf, Ans : MAIN 2011
accumulation of end products and internal CO2
concentration, etc. Oxygen is not a waste material, though it is a
by-product of photosynthesis. All organisms
216. What is the by-product of photosynthesis ? use oxygen that is given out by green plants for
respiration.
Ans : SQP 2018

Oxygen. 226. What is meant by scotoactive stomata? Give an

example.
217. What are the raw materials required for
photosynthesis ? Ans : COMP 2020

Stomata of some plants closes during daytime but

Ans : COMP 2013
opens at night, are called scotoactive stomata,
Carbon dioxide and water. e.g. allium, cabbage, opuntia.
218. What are the by-products of photosynthesis ? 227. What is meant by compensation point?
Ans : MAIN 2010 Ans : SQP 2017

Water and oxygen. When the rate of photosynthesis is equal during

dawn and dusk, it is termed as compensation
219. What happens when chlorophyll gets excited in
point.
the presence of light ?
Ans : COMP 2000
DIRECTION : Explain briefly:
The electrons are raised to a higher energy level.
228. The term destarched plant.
220. What is the advantage of destarching a plant
before the start of the photosynthetic experiment? Ans : MAIN 2002

Ans : MAIN 2005 Destarched plant lacks starch. Destarching is

done by keeping the plant in dark for 2-3 days.
Destarching ensures that no starch is present in
the plant before the start of the experiment. 229. The term photolysis in photosynthesis.
221. How do you destarch a plant ? Ans : SQP 2014

Ans : SQP 2003 Photolysis is the splitting of water molecules into

hydrogen ions and hydroxyl ions in grana in the
By keeping the plant in dark for 48 to 72 hours.
presence of chlorophyll and light.
222. Which gaseous element forms the bulk of dry
230. Chlorophyll is necessary for photosynthesis.
weight of plants ?
Ans : COMP 2018
Ans : COMP 2009
The chlorophyll traps solar energy and converts it
Carbon
into chemical energy.
223. In which part of the visible light, the transpiration
231. Light reaction is called photochemical phase.
rate is the highest.
Ans : MAIN 2005
Ans : MAIN 2004
In light reaction, light initiates a series of
In red light.
chemical reaction, which occurs in the thylakoids
224. Other name for light and dark reaction. of chloroplast.

Ans : SQP 2017 232. All life on earth would come to an end if there
Hill reaction. (light reaction). Calvin cycle (dark were no green plants.
CH 5 : PHOTOSYNTHESIS

174. The energy currency of the cell. region, which contains starch, turns______(4)
and the region, which does not contain starch,
Ans : COMP 2020
turns______(5).
Adenosine triphosphate.
Ans : SQP 2011

(1) Kill the cells

DIRECTION : Rewrite the terms in correct order in
(2) Removal of chlorophyll
a logical sequence:
(3) Iodine
(4) Blue - black colour
175. Water molecules, oxygen, grana, hydrogen and
(5) Brown colouration
hydroxyl ions, photons.
Ans : MAIN 2001
DIRECTION : Give the biological/technical term for
Photons, grana, water molecules, hydrogen and the following :
hydroxyl ion, oxygen.
181. Process of conversion of several molecules of
DIRECTION : Mention one point of difference glucose to one molecule of starch.
Ans : MAIN 2010
176. Respiration and photosynthesis (Reactants).
Polymerisation.
Ans : SQP 1996

Respiration – Glucose and oxygen DIRECTION : Given below are sets of five terms
Photosynthesis – Carbon dioxide and water each. Rewrite the terms in correct order in a logical
sequence. Example : Large intestine, Stomach,
177. Light reaction and Dark reaction. (site of
Mouth, Small intestine, Oesophagus. Answer : Mouth
occurrence).
" Oesophagus " Stomach " Small intestine "
Ans : MAIN 2010 Large intestine.
Light reaction : It occurs in the granal thylakoids
of the chloroplast. 182. Caterpillar, Snake, Owl, Frog, Green leaves.
Dark reaction : It occurs in the stroma or ground Ans : COMP 2017
matrix of the chloroplast.
Green leaves $ Catterpillar $ Frog $ Snake
$ Owl.
DIRECTION : Fill in the blanks :
DIRECTION : Answer the following :
178. Chloroplasts and______
Ans : COMP 1998 183. Mention the significance of the following minerals:
Photosynthesis. (a) Iodine in our food.
(b) Magnesium for green plants.
179. Mitochondria and______
Ans : SQP 2025
Ans : SQP 2010
(a) For synthesis of thyroxine by Thyroid gland
Respiration (b) For synthesis of chlorophyll.

184. Given below is the overall chemical equation of

DIRECTION : Copy and complete the following by photosynthesis which is incomplete in certain
filling in the blanks 1 to 5 with appropriate words / respects:
terms/phrases : CO2 + 12H2O
Chlorophyll
C6H12O6 + O2 + H2O
Rewrite the equation in complete form.
180. To test the leaf for starch, the leaf is boiled
in water to______(1). It is next boiled in Ans : MAIN 2025, 2001

methylated spirit to______(2). The leaf is

Chlorophyll
6CO2 + 12H2O Sunlight C6H12O6 + 6O2+
placed in warm water to soften it. It is then placed 6H2O
in a dish, and______(3) solution is added. The
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 175

248. Plant is boiled in methylated spirit to______. 256. The specific function of light energy in
[to remove starch, to remove chlorophyll, to kill photosynthesis is to [Synthesize glucose, activate
cells, all of these] chloroplast, split water, reduce carbon dioxide]
Ans : MAIN 2019 Ans : MAIN 2014

remove chlorophyll. Split water.

249. A destarched plant means[its leaves are without 257. Formation of ATP from ADP is termed as
chlorophyll, plant is without chlorophyll, plant is [Photophosphorylation, phosphorylation,
without starch, aerial parts (mainly leaves) are photolysis, photosynthesis]
without starch].
Ans : COMP 2009
Ans : SQP 2022
Photophosphorylation.
its aerial parts (leaves) are without starch.
258. During photosynthesis, how many water molecules
250. Example of a decomposer. [Earthworm, Insect, are required to form one molecule of glucose?
Fungi, Snail] [Twelve, ten, six, four]
Ans : COMP 2011 Ans : SQP 2019

Fungi Twelve.

259. Oxygen in glucose comes from which of these

DIRECTION : Give a logical reason for the following: during photosynthesis.
[water, CO2, air, both water and CO2]
251. ATP is needed for dark reaction.
Ans : MAIN 2023
Ans : MAIN 2023
Water.
Since ATP provides energy for dark reaction.
DIRECTION : Give exact location and function of
252. Chloroplasts are called energy converters.
the following :
Ans : SQP 2018
260. Stomata
Since chlorophyll present in chloroplasts trap
solar energy and converts it into chemical energy. Ans : SQP 2001

It is present in the epidermis of leaves. It helps in

253. Respiration is said to be reversal of photosynthesis.
exchange of gases for photosynthesis, respiration
Ans : SQP 2012 and also helps in transpiration.
Because respiration is a catabolic process while
261. Grana
photosynthesis is an anabolic process.
Ans : MAIN 2019
254. Chlorophyll is necessary for photosynthesis.
Found in chloroplast. It is the site of light reaction
Ans : COMP 2010 of photosynthesis.
Chlorophyll traps solar energy and converts it
262. Guard cells
into chemical energy.
Ans : COMP 2011

DIRECTION : Completed the following sentences Found in the epidermis of leaves around the
with appropriate words. stomata. It controls the opening and closing of
stomata.
255. The first step in the process of photosynthesis is:
263. Thylakoids
[absorption of light by chlorophyll, production of
ATP, release of oxygen, fixation of CO2] Ans : COMP 2017

Ans : SQP 2002 Inside the chloroplast in the form of piles to form
granum. It helps to trap sunlight and initiates the
Absorption of light energy by chlorophyll.
process of photosynthesis.
CH 5 : PHOTOSYNTHESIS

of CO2 by green plants during phtosynthesis. (i) State the aim of the above experiment.
During respiration, all organism take oxygen and (ii) Name the chemical used for testing the
Photosynthesis give out CO2 into the atmosphere. presence of starch.
During combustion of wood or coal, CO2 is (iii) Why is the leaf boiled in water and alcohol
given out. This circulation of carbon through before testing for the presence of starch ?
autotrophs, animals and combustion is called (iv) What change is seen on the leaf after the
carbon cycle. starch test?
(v) Give the chemical equation to represent the
process of starch formation in plants.
Ans :
FIVE MARKS QUESTIONS
SQP 2003

(i) To prove that chlorophyll is necessary for

photosynthesis.
292. Study the diagram given below and fill in the (ii) Iodine solution.
blanks with suitable words: (iii) Boiling kills cells and alcohol is a solvent for
chlorophyll.
(iv) The green parts turn blue black while non-
green parts turn brown.
(v) 6CO2 + 12H2O $ C6H12O6 + 6H2O + 6O2
n(C6H12O6) $ (C6H10O5)n + nH2O

294. The diagram given below represents an

experiment to prove the importance of a factor in
photosynthesis. Answer the questions that follow :

In order to prove that carbon dioxide is necessary

for (i) .............. a potted plant is placed in
dark for 48 hours to (ii) .............. the leaves.
A part of a leaf is inserted into a conical flask
containing potassium hydroxide solution. This is
to absorb (iii) .............. from the flask. The plant
is then placed in sunlight for a few hours. The
experimental leaf is tested for starch. The part
of the leaf that was inside the conical flask turns (i) Name the factor studied in this experiment.
(iv) .............. whereas the part of the leaf outside (ii) What will you observe in the experimental
turns (v) .............. in colour. leaf after the starch test ?
(iii) Explain the process of photosynthesis.
Ans : MAIN 2024 (iv) Give a balanced chemical equation to
(i) Photosynthesis represent the process of photosynthesis.
(ii) Destarch (v) Draw a neat, labelled diagram of an
(iii) Carbon dioxide experimental setup to show that oxygen is
(iv) Brown released during photosynthesis.
(v) Blue-black Ans : MAIN 2019

293. A healthy Croton plant bearing variegated leaves (i) Sunlight

was kept in a dark cupboard to destarch it, after (ii) The exposed parts will turn blue-black with
which it was placed in sunlight for few hours. One iodine solution while the part covered with
of the leaves was then plucked and an outline of black paper strip turns brown.
the leaf marking the green and non-green regions (iii) The process by which green plants containing
was drawn. The leaf was then tested for starch. chlorophyll produce food (glucose) from
Using the above information, answer the following carbon dioxide and water by using light
questions : energy.
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Ans : SQP 2015
TWO MARKS QUESTIONS
Light reaction Dark reaction
Light reaction occurs in Dark reaction occurs 277. Enumerate the steps involved in testing a green
the thylakoids/grana of in the stroma of the leaf for the presence of starch.
the chloroplast. chloroplast. Ans : MAIN 2005

273. Light reaction and Dark reaction. Step I – Dip the leaf in boiling water for a minute
to kill the cells.
Ans : MAIN 2011
Step II – Boil the leaf in methylated spirit to
remove chlorophyll.
Light reaction Dark reaction
Step III – Put the leaf in normal water to make
(a) It takes place in the It does not require it soft.
presence of light. light. Step IV – Put iodine solution. It turns starch blue
(b) It occurs in It occurs in black.
the grana of the stroma of
chloroplast. chloroplast. 278. Draw a neat labelled diagram of the experimental
set up to show that green plants give out oxygen
(c) Its products are Its products are
during photosynthesis.
ATP and NADPH. organic compounds.
Ans : SQP 2001, 1997

274. Autotrophs and Heterotrophs.

Ans : COMP 2017

Autotrophs Heterotrophs
(a) They can prepare They cannot prepare
their own food. their own food.
(b) They contain They do not contain
chlorophyll. chlorophyll.

275. Stroma and Grana.

Ans : MAIN 2011

Stroma of Grana of
Chloroplast Chloroplast
(a) It is the site of dark It is the site of light
reaction. reaction. 279. Explain the following terms :
(b) It is a non-green It is green flattened (i) Photolysis
granular matrix. sac-like structure. (ii) Photolysis in photosynthesis
(iii) bestarched plant
276. Chloroplast and Chlorophyll. Ans : MAIN 2010, 2009, 2006

Ans : SQP 2001 (i) Photolysis : The splitting of water molecules

into hydrogen ions and hydroxyl ions with the
Chloroplast Chlorophyll help of light energy.
(ii) Photolysis in photosynthesis : The splitting
(a) It is an organelle of It is the green
of water molecules into hydrogen ions and
the cell. pigment in
hydroxyl ions with the help of light energy.
chloroplast.
(iii) Destarched plant is a plant kept in the
(b) It is living. It is non-living. darkness for 24 – 72 hours, to make it starch
CH 5 : PHOTOSYNTHESIS

199. What is photophosphorylation? The manufacturing of glucose by green plants

with the help of carbon dioxide and water in the
Ans : SQP 2021
presence of sunlight and chlorophyll.
It is the conversion of ADP with inorganic
phosphate group to ATP in the presence of light. 208. Mention two significant advantages of
photosynthesis to the living world as a whole.
200. What are thylakoids?
Ans : SQP 2017
Ans : MAIN 2014
(a) To provide food for all organisms.
These are disc-shaped membranous sacs present (b) To release oxygen which is a life supporting
in grana of the chloroplast. gas.
201. How does the raw materials reach the plant cell? 209. What are the end products of light reaction?
Ans : COMP 2018 Ans : COMP 2009

The raw materials required by plants are water, Oxygen, NADPH, ATE
CO2 and sunlight. Water enters into the leaf
through the midrib and veins from the stem and 210. What is biosynthetic phase?
root. CO2 enters through the stomata from the Ans : MAIN 2019
atmosphere.
It is called dark reaction which occurs in the
202. How does sunlight affects photosynthesis? stroma of chloroplast in absence of light (light is
not required), and glucose is produced.
Ans : SQP 2020

Light provides energy for photosynthesis. Light 211. What is photolysis?

intensity is directly proportional to photosynthesis. Ans : COMP 2014

203. State the role of ATP. The process of splitting of water by sunlight
during light reaction is called photolysis.
Ans : MAIN 2007

ATP provides energy for all biosystems to 212. Light reaction is also called photochemical
function. It is the energy currency of the cell. reaction. Why?

204. What is NADP? Ans : SQP 2011

Light reaction takes place in the grana of

Ans : COMP 2003
chloroplast in presence of light, so it is called
It is an enzyme. Its full form is Nicotinamide photochemical reaction.
Adenine Dinucleotide Phosphate. During electron
transfer, NADP gets reduced to NADPH2. 213. State the role of chlorophyll.

205. Where does photosynthesis mostly take place in Ans : MAIN 2004

a plant? Chlorophyll absorbs photons of sunlight, gets

excited and helps in the splitting of water
Ans : MAIN 2016
molecules into hydrogen ions and hydroxyl ions.
In plants, photosynthesis takes place in
chloroplasts present in the leaf.

206. What is the optimum temperature for

photosynthesis?
Ans : SQP 2010

30-35°C is the optimum temperature needed for 214. Write the summary of dark reaction by an
photosynthesis. equation.

207. What is photosynthesis? Ans : COMP 2009

6CO2 + 12NADPH + 18ATP $ C6H12O6 +

Ans : MAIN 2023
12NADP + 18ADP + 18Pi + 6H2O.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 179

286. Distinguish between Respiration and (1) Light phase or photochemical phase takes
Photosynthesis. place in granum of chloroplast wherein
chlorophyll molecules are present which get
Ans : MAIN 2017
excited in the presence of light by absorbing
photons.
Respiration Photosynthesis
(2) The absorbed energy splits water molecules
(i) O2 is used up. (i) O2 is given out. into hydrogen ion and hydroxyl ion.
(ii) Glucose is (ii) Glucose is (3) The hydrogen ions are then accepted by
broken down. formed. NADP to form NADPH.
(4) The hydroxyl ions react with each other to
(iii) Chlorophyll is (iii) Chlorophyll is
form oxygen which is given out as molecular
not required. required.
oxygen.
(5) The energy contained within the excited
287. Give scientific reasons: electrons of chlorophyll molecules are utilized
(a) It is not possible to demonstrate respiration in converting ADP into energy rich ATP.
in green plants in daytime.
(b) Some leaves have shiny and green upper 290. Write an experiment to prove that O2 is given out
surface. during photosynthesis.
(c) Chloroplasts are called as energy converters.
Ans : COMP 2019
Ans : SQP 2006
To show that O2 is released during photosynthesis.
(a) During day time, green plants use up CO2 Take a beaker containing pond water. Keep some
released during respiration for photosynthesis, Hydrilla plants in a funnel in the beaker. Insert a
it is not possible to measure the CO2 release test-tube full Bubbles of gas of water. Make sure
and take in. that the level of water in the beaker is above the
(b) Upper surface contain more waxy cuticle and level of the stem of the funnel. Keep the apparatus
more chloroplasts are present on this surface in the sun for a few hours. Bubbles of gas will
to absorb light energy. collect in the test tube. Test the gas by a glowing
(c) Chloroplasts contain the green pigment splinter, it will bursts into flame. This shows that
chlorophyll which trap sunlight for the oxygen is evolved during photosynthesis.
photosynthesis and convert it into chemical
energy.

288. (a) Give the overall chemical equation of

photosynthesis in green plants.
(b) Mention two significant advantages of
photosynthesis to the living world.
Ans : MAIN 2011
Chlorophyll
(a) 6CO2 + 12H2O Sunlight C6H12O6 + 6H2O
+ 6O2 -
(b) Two significant advantages of photosynthesis
to the living world are as follow :
(i) Photosynthesis causes the production of
food. The various types of organic food
which animals need as food comes from
plants.
(ii) Plants use carbon dioxide (liberated
during respiration) and liberate life-
supporting oxygen, which is used for 291. Explain carbon cycle.
respiration.
Ans : MAIN 2009
289. Write in steps the light phase of photosynthesis. All organic compounds contain carbon. Carbon
Ans : SQP 2017 is absorbed from the atmosphere in the form
CH 5 : PHOTOSYNTHESIS

DIRECTION : Mention any two differences between (v) CO2 and water (e) workrooms
each of the following :
(vi) Cells in the leaf (f) end product
264. Autotrophs and heterotrophs (vii) Grana (g) power.
Ans : SQP 2006 Ans : SQP 2017

Autotrophs Heterotrophs (i) – (d), (ii) – (f), (iii) – (b),

(iv) – (g), (v) – (c), (vi) – (e), (vii) – (a).
(a) Produce their own Cannot prepare
food. their own food. 269. Without changing the first term rearrange the
(b) Contain chlorophyll. Do not contain remaining terms in logical sequence. Destarched
chlorophyll. plant, iodine added, washed in water, a leaf boiled
in alcohol, placed in sunlight (testing the presence
265. Chloroplast and chlorophyll of starch).

Ans : COMP 2010 Ans : MAIN 2021

Destarched plant $ placed in sunlight $ a leaf

Chloroplast Chlorophyll boiled in alcohol $ washed in water $ iodine
(a) An organelle of a Green pigment in added.
cell. chloroplast.
270. Given below are certain biological statements
(b) Living. Non-living. which are incomplete and hence incorrect. Rewrite
the correct form of the statement by inserting a
266. Stroma and grana suitable word/words at the right place. Do not
delete any word already given in the statement.
Ans : MAIN 2003
Underline the inserted word/words.
(a) Destarching a plant means removing the
Stroma Grana
starch from the plant.
(a) Site of dark Site of light (b) The splitting of water molecules into hydrogen
reaction. reaction. ions and hydroxyl ions is termed photolysis.
(b) Non green granular Green flattened sac Ans : SQP 2012
matrix. like structure.
(a) Destarching a plant means removing the
starch from the leaves of the plant.
267. Light reaction and dark reaction (b) The splitting of water molecules in the presence
Ans : SQP 2015 of sunlight in grana of the chloroplast into
hydrogen ions and hydroxyl ions is termed as
Light reaction Dark reaction photolysis.
(a) Takes place in the It does not require
presence of light. light DIRECTION : Distinguish between the following
pairs:
(b) It occurs in grana It occurs in stroma
of chloroplast. of chloroplast.
271. Tonoplast and plasma membrane (Location).
268. Match the items given in column I with those in Ans : MAIN 2008
column II.
Tonoplast Plasma membrane
Column I Column II
Surrounds the vacuole. Surrounds the cell
(i) Oxygen and (a) Stimulated by
(Both in animal and
water light
plant cell)
(ii) Glucose (sugar) (b) machinery
(iii) Chloroplast (c) raw materials 272. Light reaction and Dark reaction. (site of
occurrence)
(iv) Sunlight (d) by-products
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 181

(iv) 6CO2+ 12H2O

Sunlight
Chlorophyll C6H12O6 + 6H2O + (iii) State any two differences in these processes
6O2 other than those already indicated in the
(v) reactions.
(iv) Which one of these two reactions is the
support of all life on earth ?
Ans : COMP 1994

(i)
1. 6CO2 + 12H2 O Chlorophyll
Sunlight C6 H12 O6 + 6O2 + 6H2 O

2. C6 H12 O6 + 6O2 6CO2 + 6H2 O

Respiration

+ Energy
(ii) Photosynthesis and respiration.
(iii)
295. A candidate in order to study the importance of
certain factors in photosynthesis, took a potted Respiration Photosynthesis
plant and kept in the dark for over 24 hours. Then 1. Occurs in all the Occurs in
in the early hours of the morning she covered one living cells. chlorophyllous cells
of the leaves with black paper in the centre only. only.
She placed the potted plant in the sunlight for
2. It takes place at It takes place in the
a few hours and then tested the leaf which was
all times without presence of light
covered with black paper for starch.
interruption. only.
(i) What aspect of photosynthesis was being
investigated ? (iv) Photosynthesis.
(ii) Is there any control in this experiment ? If so
state the same. 297. Answer the following :
(iii) Why was the plant kept in the dark before (i) Name the two phases of photosynthesis.
the experiment ? (ii) What is the role of light in this process ?
(iv) Describe step by step how the candidate (iii) Describe any three adaptations in a green leaf
proceeded to test the leaf for the presence of for photosynthesis.
starch. (iv) Describe an experiment to show that light is
necessary for photosynthesis.
Ans : SQP 1999 (v) Sleeping under a tree at night is not advisable.
(i) To show that sunlight is needed for Ans : SQP 2010
photosynthesis.
(i) 1. Light reaction (Photolysis of water).
(ii) Yes, the uncovered portion of the experimental
2. Dark reaction (CO2 reduction).
leaf is the control.
(ii) Light has energy giving photons which
(iii) To destarch the leaf.
activate and ionise chlorophyll to release
(iv) 1. Boil the leaf in alcohol to remove electrons. The electrons (split) ionise water
chlorophyll. molecules. The process is called photolysis.
2. Wash the leaf in water to make it soft.
3. Add iodine solution on the leaf.
The portion uncovered shows blue-black
colour and the portion covered shows brown
colour. This indicates that sunlight is needed
for photosynthesis.

296. (i) Fill in the blanks in the following equations of The H+ reduces CO2 to form carbohydrates.
two chemical reactions : (iii) 1. Large surface area : The surface area of
the leaves is very large for the absorption
of maximum light energy from the
sunlight.
(ii) Name the two processes represented by the 2. Leaf arrangement : The leaves are
above two reactions. arranged on the stem in such a way so
CH 5 : PHOTOSYNTHESIS

at the end of the starch test ?

Ans : SQP 2021

(i) Carbon dioxide is necessary for photosynthesis.

(ii) KOH absorbs all CO2 from the flask and the
leaf gets no CO2 for photosynthesis.
(iii) NaOH (Sodium hydroxide).
(iv) Leaf 1 will not turn blue black with iodine
solution (negative starch test) while. Leaf 2
will turn blue black when tested with iodine
solution (positive starch test).
Ans : COMP 2015

(i) Aim – To show that starch is formed in 304. The diagram below shows two test-tubes A and
photosynthesis. B. Test-tube A contains a green water plant.
(ii) 1. To a healthy green leaf cover a portion Test-tube B contains both a green water plant
of it on both sides with black paper fixed and a snail. Both test-tubes are kept in sunlight.
in position with two paper clips either in Answer the questions that follow :
the morning before the sun rises or the
previous evening, so that the experiment
is done with a starch-free leaf.
2. Expose the plant to sunlight for about
6-8 hours.
3. Collect the leaf and decolourise it with
alcohol.
4. Dip it into iodine solution.
5. Note that the exposed portions turn blue-
black showing the presence of starch,
while the screened portion (Portion under
the black paper) turns yellowish brown,
there being no starch formed in it.
(iii) Conclusion – It proves that light is necessary
for the manufacture of starch. (i) Name the physiological process that releases
the bubbles of oxygen.
303. The figure given below represents an experiment to (ii) Explain the physiological process as mentioned
demonstrate a particular aspect of photosynthesis. above in (i).
The alphabet ‘A’ represents a certain condition (iii) What is the purpose of keeping a snail in test-
inside the flask. tube ‘B’ ?
(i) What is the aim of the experiment ? (iv) Why does test-tube ‘B’ have more bubbles of
oxygen?
(v) Give an example of a water plant that can be
used in the above experiment.
(vi) Write the overall chemical equation for the
above process.
Ans : MAIN 2017

(i) The physiological process is Photosynthesis.

(ii) The physiological process by which green
plants in the presence of sunlight and
chlorophyll prepare food in the form of
glucose (carbohydrate) using carbon dioxide
(ii) Identify the special condition inside the flask. and water.
(iii) Name an alternative chemical that can be (iii) The snail respires and releases CO2 which
used instead of KOH. acts as a source of CO2. The plant uses it in
(iv) In what manner do the leaves 1 and 2 differ the process of photosynthesis.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 183

alcohol so that the green colouring matter of (2) To remove all chlorophyll from the leaf
the leaf called chlorophyll dissolves in alcohol. cells and make it colourless.
The leaf is then washed under the tap and (iv) Iodine solution
tested with iodine for starch. The region or (v) The part of the leaf which is covered with
the part of the leaf that was covered with black paper will not turn blue black with
black paper turns yellowish-brown. It shows iodine solution since it did not receive sunlight
that no starch was manufactured while the so it could not manufacture starch.
Chlorophyll
rest of the part of the leaf turns blue-black. It (vi) 6CO2 + 12H2O Sunlight C6H12O6 + 6O2 +
proves or demonstrates that starch was made 6H2O
in the leaf in the presence of sunlight.
301. The figure represents an experiment set up to
300. The given diagram represents an experiment study a physiological process in plants :
conducted to prove the importance of a factor in
Photosynthesis. Study the same and then answer
the questions that follow :

(i) Name the physiological process being studied.

(i) Name the factor being studied in this (ii) Explain the process.
experiment. (iii) What is the aim of the experiment ?
(ii) Why was the plant kept in a darkroom before (iv) Give a well balanced equation to represent
conducting the experiment ? the process.
(iii) Why was the experimental leaf then kept in :
(1) boiling water Ans : MAIN 2001

(2) methylated spirit ? (i) Photosynthesis.

(iv) Name the solution used to test for the (ii) During daytime, when the sunlight falls on
presence of starch in the leaf. green tissues say leaf, the sunlight is trapped
(v) What will we observe in the experimental leaf by the chlorophyll specially of the palisade
at the end of the starch test ? cells, is utilized in chemical processes of
(vi) Give a balanced chemical equation to manufacturing food, from raw materials such
represent the process of photosynthesis. as CO2 and H2O.
(iii) Oxygen is produced during photosynthesis.
Ans : SQP 2009
Sunlight
(iv) 6CO2 + 12H2O C6H12O6 + 6H2O + 6O2
(i) Light is necessary for photosynthesis. Chlorophyll

(ii) The plant was kept in the darkroom before 302. The figure given here is for performing an
conducting the experiment in order to experiment on photosynthesis. Answer the
destarch it so that to ensure that no starch is following :
present in the leaves before the experiment. (i) What is the aim of this experiment ?
(iii) (1) To destroy all enzymes in the leaf cell (ii) Describe an experiment to show that light is
so that no further chemical changes take necessary for photosynthesis.
place. Moreover, to make the leaf cells (iii) you conclude from this experiment?
permeable to iodine solution.
CH 5 : PHOTOSYNTHESIS

that maximum surface area of leaves is (iii) Name an alternative chemical that can be
exposed to sunlight. used instead of KOH.
3. Chloroplasts : Chloroplasts containing (iv) In what manner do the leaves 1 and 2 differ
chlorophyll are concentrated in the upper at the end of the starch test?
layers of the leaf. It helps in trapping
maximum radiant energy from the
sunlight quickly.
(iv) Aim : To demonstrate that light is necessary
for photosynthesis.
Requirements : A destarched potted plant,
Ganong’s light screen.
Procedure :
1. Take Ganong’s light screen.
2. Fix the Ganong’s light screen to one of
the leaves of the potted plant (destarched
) as shown in Figure.
3. Keep the plant with fixed light screen in Ans : MAIN 2013

light at least for 6 hours. (i) To show that CO2 is needed for photosynthesis.
4. Perform the starch test. (ii) There is no CO2 inside the flask.
(iii) Soda lime.
(iv) Leaf 1 does not contain starch so it won’t
change into blue-black colour. Leaf 2 shows
colour change (blue-black) as starch is present
in it.

299. A potted destarched plant was taken in order to

prove that light is necessary for photosynthesis.
(i) What is meant by destarched plant ? How
can it be destarched ?
(ii) Using the destarched plant describe step
by step how you would proceed to prove
that in the absence of light the leaf cannot
manufacture starch.
Ans : SQP 1996
Observations : It is observed that the middle
(i) A destarched plant has no starch in the
portion of screen which allows the light to
leaves and the leaf remains yellowish brown
fall on leaf gives positive starch test and
when the leaf is tested for starch with iodine
the portion covered with light screen gives
solution.
negative starch test.
A plant can be destarched when it is kept in
Inference : Light is necessary for
the darkroom for about 24 hours. The plant,
photosynthesis.
thus, by keeping in darkroom can be made
(v) Sleeping under a tree at night is not advisable starch-free.
because there is no photosynthesis in
(ii) A destarched plant from a darkroom is taken
darkness. Rather plants release large amount
and its leaf is covered with black paper on
of CO2 due to respiration.
both the sides by means of Mohr’s clip.
298. The figure given below represents an experiment to The potted plant is now brought out in the
demonstrate a particular aspect of photosynthesis. sunlight. The plant is kept here for about 7
The alphabet ‘A’ represents a certain condition to 8 hours in the sunlight. The leaf is now
inside the flask. detached and the black papers are removed
(i) What is the aim of the experiment? away. Now, the leaf is boiled in water for
(ii) Identify the special condition inside the flask. about 5 to 6 minutes. Then, it is boiled in
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 185

(iv) Test tube B has more bubbles of oxygen (v) Rate of bubbling will increase by the addition
because the snail releases CO2 during of a pinch of sodium bicarbonate.
respiration due to which CO2 level increases in.
the test tube hence the rate of photosynthesis 306. Pondweed was placed in a test tube containing
also increases and more oxygen bubbles come pond water and exposed to bright sunlight.
out. Bubbles were seen coming up in the water after
(v) An example of a water plant that can be used some time.
in this experiment is Hydrilla. (i) Name the gas evolved.
sunlight (ii) What is the source of the gas ?
(vi) 6CO2 + 12H2O chlorophyll C6H12O6 + 6O2 + 6H2O (iii) For each of the following parts give your
305. The following diagram demonstrates a answer in terms of bubble count. What would
physiological process taking place in green plants. happen if:
The whole set up was placed in bright sunlight for
several hours. Study the diagram and answer the
questions that follow :

(a) Pond water is replaced by distilled water.

(b) The apparatus is kept in dark.
(i) What aspect of the physiological process is (c) The apparatus is placed in green light.
being examined ? (d) A pinch of sodium bicarbonate is added
(ii) Explain the physiological process mentioned to water in the test tube.
in (i) above. (e) Crushed ice is added to the water in the
(iii) Label the parts numbered 1 and 2 in the test tube.
diagram. Ans : MAIN 2000
(iv) Write a well-balanced chemical equation for
(i) Oxygen
the physiological process explained in (ii)
(ii) Oxygen is given out due to photolysis of water
above.
(iii) (a) Bubble count decreases.
(v) What would happen to the rate of bubbling
(b) Bubble count decreases to almost
of the gas if a pinch of sodium bicarbonate
negligible.
is added to the water in the beaker? Explain
(c) Bubble count decreases (photosynthesis
your answer.
is minimum in green light and maximum
Ans : SQP 2016 in red light).
(i) Oxygen is evolved during photosynthesis. (d) Bubble count increases (as sodium
(ii) Photosynthesis is a physiological process bicarbonate gives out carbon dioxide).
during which green plants synthesize complex (e) Bubble count decreases (photosynthesis
organic compounds (Glucose) from simple rate decreases with decrease in
inorganic compounds-CO2 and H2O in the temperature).
presence of sunlight and chlorophyll.
307. The diagrams given below represent the
(iii) 1-Oxygen, 2- Green aquatic plant
relationship between a mouse and a physiological
Light
(iv) 6CO2 + 12H2O Chlorophyll C6H12O6 + 6H2O process that occurs in green plants. Study the
+ 6O2 diagrams and answer the questions that follow:
CH 5 : PHOTOSYNTHESIS

2. Carotenoids become visible before leaf fall 3. Carbohydrates are used for respiration, food
because chlorophylls break down first. storage, and growth.
3. The essential requirements for photosynthesis 4. Starch is detected by turning blue-black in
are light, chlorophyll, carbon dioxide, and the presence of iodine solution.
water.
4. Chlorophyll's role is to capture sunlight and 315. In a biology experiment, Two healthy green plants
convert it into chemical energy. were placed in the dark for 24 hours. They were
then set up as shown in the figure and left for four
313. Students learned that photosynthesis has two hours. Then a leaf was taken from each plant and
phases: the light reaction, which produces ATP the chlorophyll was removed from the leaves.
and NADPH, and the dark reaction, where carbon
dioxide is fixed to form glucose. They also found
that glucose is converted into starch.
1. What are the two phases of photosynthesis?
2. Where does the light reaction occur, and
what are its end products?
3. What is the role of RuBP in the dark reaction?
4. How is glucose converted into starch after its
production?
(i) How is chlorophyll removed ?
Ans :
(ii) What is the next and final step in this
1. The two phases of photosynthesis are the experiment?
light reaction and the dark reaction. (iii) What would be the result of the final step ?
2. The light reaction occurs in the thylakoids of (iv) Why is it necessary to grease the glass sheet ?
the chloroplast, and its end products are ATP (v) What hypothesis is being tested in this
and NADPH. experiment?
3. RuBP (Ribulose bisphosphate) is the primary
Ans : MAIN 2005
acceptor of carbon dioxide in the dark
reaction. (i) The chlorophyll is removed by boiling the leaf
4. Glucose produced during photosynthesis in alcohol or ether.
is converted into starch by the process of (ii) The leaf is then treated with iodine solution.
polymerization. (iii) The leaf from plant A would not show starch
test while the leaf from plant B would become
314. Students learned about photorespiration, blue black showing the presence of starch.
photosynthesis, and performed experiments (iv) It is necessary to grease the glass sheet to
using Ganong's light screen and iodine solution prevent the entry of air containing carbon
to demonstrate the importance of light in dioxide.
photosynthesis. (v) The hypothesis that carbon dioxide is
1. What is the process of photorespiration? necessary for photosynthesis is being tested
2. How does Ganong’s light screen help in this experiment.
demonstrate that light is necessary for
photosynthesis? 316. A diagrammatic representation of the internal
3. What are the three main uses of carbohydrates structure of an organelle found in a plant cell
formed during photosynthesis? is shown. Study the same and then answer the
4. How is starch detected in leaves during questions that follow :
experiments on photosynthesis?
Ans :
1. Photorespiration is the uptake of oxygen
and release of carbon dioxide in light by
photosynthesizing tissue.
2. It blocks light in parts of the leaf to show
that photosynthesis only occurs where light is
available.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 187

performed on leaf ‘A’ shown in the diagram? (ii) One vein has been shown.
Give an example of a plant with variegated (iii) Xylem – helps in the conduction of water.
leaves. Stoma – through which exchange of gases
(v) Draw a neat labelled diagram of a chloroplast. takes place (CO2 and O2).
Ans : SQP 2017

(i) Chlorophyll is necessary for photosynthesis.

(ii) 6CO2 + 12H2O
Chlorophyll
Sunlight C6H12O6 + 6H2O CASE BASED QUESTION
+6O2
(iii) To destarch the leaves.
(iv) The green part of the leaf turns blue black 311. In a biology experiment, students observed how
and the pale yellow part will turn brown with sunlight is converted into chemical energy in green
iodine solution at the end of starch test. plants. They learned that this process occurs in
Example: Coleus/Geranium/Croton/ specific parts of the cell, with most photosynthesis
Tradescantia taking place in the oceans.
(v) 1. What process converts sunlight into chemical
energy in plants?
2. Where in the plant cell does the light reaction
occur?
3. What is the role of chloroplasts in
photosynthesis?
4. How many chloroplasts are typically found in
a leaf cell?
Ans :
1. The process that converts sunlight into
chemical energy in plants is photosynthesis.
2. The light reaction of photosynthesis occurs in
310. The figure represents the vertical section of a leaf:
the grana of the chloroplasts.
3. Chloroplasts are responsible for capturing
sunlight and facilitating the conversion of
light energy into chemical energy.
4. There are typically 40 to 50 chloroplasts
present in each leaf cell.

312. Students in a biology class learned that pigments

like chlorophyll and carotenoids are involved
in photosynthesis. They also discovered that
light, carbon dioxide, water, and chlorophyll are
essential for the process to occur.
1. What are the two major groups of pigments
involved in photosynthesis?
2. Why do carotenoids become visible before
leaf fall?
3. What are the essential requirements for
photosynthesis?
(i) Name the parts 1 to 5.
4. What is the role of chlorophyll in
(ii) How many veins have been shown in the
photosynthesis?
section?
(iii) State the functions of part 4 and 5. Ans :
Ans : COMP 2012 1. The two major groups of pigments involved
in photosynthesis are chlorophylls and
(i) 1 – Cuticle, 2 – Upper epidermis, 3 – Palisade
carotenoids.
tissue/Chloroplast, 4 – Xylem, 5 – Stoma
CH 5 : PHOTOSYNTHESIS

(ii) During photochemical reaction, the following

processes take place:
1. Photolysis of water, splitting of water
(i) Name the physiological process occurring in molecules into hydrogen and hydroxyl
the green plant that has kept the mouse alive. ions.
(ii) Explain the physiological process mentioned
H2O $ H+ + OH–
above.
(iii) Why did the mouse die in bell jar B? 2. Production of NADPH2
(iv) What is the significance of the process as NADP + 2H+ + 2e– $ NADPH2
stated in (i) for life on earth? 3. Formation of molecular oxygen
(v) Represent the above mentioned physiological 4OH + 4e– $ 2H2O + O2
process in the form of a chemical equation.
4. Photophosphorylation
Ans : MAIN 2003
ADP + Pi $ ATP
(i) Photosynthesis. (iii) (a) White light It has all the wavelength of
(ii) Photosynthesis is the process by which visible light.
green plants in the presence of sunlight (b) Destarched plant is used as control plant.
and chlorophyll prepare food in the form
of carbohydrates using carbon dioxide and 309. A potted plant with variegated leaves was
water. taken in order to prove a factor necessary for
(iii) Mouse died in bell jar B because the source of photosynthesis. The potted plant was kept in
oxygen i.e., the green plant was missing and the dark for 24 hours and then placed in bright
the oxygen present in the bell jar was utilized sunlight for a few hours. Observe the diagrams
in burning of candle. and answer the questions.
(iv) Photosynthesis provides food and balances the
oxygen and carbon cycle in the atmosphere.
Chlorophyll
(v) 6CO2 + 12H2O Sunlight C6H12O6 +6O2 +
6H2O

308. (i) Draw a neat and well-labelled diagram of the

chloroplast.
(ii) List the events taking place in the
photochemical phase of photosynthesis.
(iii) If you are planning an experiment to show
the effect of light on photosynthesis:
(a) Will you select white light or green light? (i) What aspect of photosynthesis is being tested
Justify your answer. in the above diagram?
(b) Why would you select a destarched plant? (ii) Represent the process of photosynthesis in
the form of a balanced equation.
Ans : SQP 2001
(iii) Why was the plant kept in the dark before
(i) beginning the experiment?
(iv) What will be the result of the starch test
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 189

(i) Identify the organelle.

(ii) Name the physiological process occurring in
this organelle.
(iii) Mention one way in which this process is
beneficial to man.
(iv) Name the phases of the process occurring in
the parts labelled ‘1’ and ‘2’.
(v) A chemical substance ‘NADP’ plays an active
part in one of the phases. Give the expanded
form of NADP and state its role in the above
process.
(vi) Represent the physiological process mentioned
in (ii) above in the form of a chemical
equation.
Ans : SQP 2019

(i) The given organelle is chloroplast.

(ii) Photosynthesis.
(iii) Oxygen is released during photosynthesis
which is required for breathing by man.
(iv) (1) Dark Reaction.
(2) Light Reaction.
(v) NADP-Nicotinamide Adenine Dinucleotide
Phosphate. It acts as a hydrogen carrier.
(vi) 6CO2 + 12H2O $ C6H12O6 + 6O2 + 6H2O

www.nodia.in
CH 6 : CHEMICAL COORDINATION IN PLANTS

CHAPTER 6
CHEMICAL COORDINATION IN PLANTS

Cytokinins.
SUMMARY (b) The growth inhibitors : Abscisic acid and
Ethylene.
Growth is one of the most fundamental
characteristics of all living organisms. In plants, 2. DISCOVERY OF PLANT GROWTH REGULATORS
growth takes place by cell division and cell (PLANT HORMONES)
enlargement. The main areas of growth by cell
The first indication of its exitance was given by
division in plants is meristems which occur just
Darwin (1880), who was studying the bending of
behind shoot and root tips.
the coleoptile of a Canary grass towards light.
In plants, movement are seen in the form of
He found that light falling on the tip of grass
bending, twisting and elongation of certain parts.
coleoptile causes some influence. This influence
They do not need a fast response to small changes
(hormone) is transmitted downward and causes
in their immediate environment. They do need to
the coleoptile to bend towards light. He also
respond to light, gravity and seasonal changes.
demonstrated that when the coleoptile tip was
They also need to coordinate growth of cells in
removed it did not bend when exposed to light.
various parts of the plant body. Nervous system
The phototropic response did not occur.
or sense organs are not present in plants but
their sensitivity and coordination is the result of 2.1 Functions of Plant Hormones (Phytohormones)
chemical control exercised by plant hormones.
The various functions are as follows :
Plants respond to stimuli by producing
1. Flowering of plants
hormones, similar to hormones of animals. The
2. Ripening of fruits
main way in which plants respond to these
3. Germination of seeds
hormones is by growth. With the help of hormones,
4. Breaking dormancy of seeds
growth is stimulated or inhibited in plants.
5. Stomatal movement in leaves
1. PLANT GROWTH REGULATORS 6. Phototropism, geotropism, chemotropism,
hydrotropism, thigmotropism and nastic
It is an established fact that plants produce some
movements.
specific chemical substances, which are capable
of moving from one organ to the other, so as to 3. PHYSIOLOGICAL EFFECTS OF PLANT GROWTH
produce their effect on growth. These substances, REGULATORS (PLANT HORMONES)
which are active in very small amounts are called
plant hormones (or Phytohormones). 3.1 Auxins
The term phytohormone (phyton = plant) was
Auxins (Gk. Auxein : to grow) are the first group
coined to distinguish them from animal hormones.
of plant hormones which are produced from the
The term hormone was given by William
root and shoot-tips of the plant body, from where
Bayliss and Ernest Starling.
they migrate to the region of their action.
1.1 Classification of Hormones They were first discovered by F. W. Went (1928)
while experimenting on oat plant (Avena sativa).
Hormones are divided into five major classes, namely:
Auxins are of following two types:
(1) Auxins, (2) Gibberellins, (3) Cytokinins,
(A) Natural auxins are Indole acetic acid (IAA)
(4) Abscisic aciu and (5) Ethylene.
and Indole butyric acid (IBA).
These five hormones are divided into two groups:
(B) Synthetic auxins are 2, 4 - dichlorophenoxy acetic
(a) The growth promotors : Auxins, Gibberellins,
acid (2, 4 -D) and Naphthalene acetic acid (NAA).
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 191

Physiological Effects on Plants : 3.3 Cytokinins

1. Auxins promote cell elongation and growth of Cytokinins are the hormones which promote
stems and roots. It also promotes enlargement cytokinesis in cells of various plant origins and
of many fruits by stimulating elongation of prevent ageing in tissues. They have little or no
cells in all directions. effect on growth.
2. In many plants, the apical bud grows and Physiological Effects on Plants :
lower axillary buds are suppressed. Removal Physiological effects on plants are as follows :
of apical buds results in the growth of lower 1. In the presence of auxin, cytokinins stimulate
buds. The auxin of the terminal buds inhibits cell division.
the growth of lateral buds. This phenomenon 2. Cytokinins delay ageing process in plant
is called Apical dominance. organs by controlling protein synthesis.
3. Weeds are unwanted plants growing in a field 3. Cytokinins break the dormancy of many seeds
alongwith a crop that do not allow proper and promote their germination.
growth of the crop. By spraying auxin they 4. These help in the translocation of solutes in
can be destroyed and removed. phloem.
4. If the lower cut ends of rose and Bougainvillea 5. Cytokinins provide resistance to plants
are dipped in auxins, very soon large number injured by high or low temperatures.
of roots are developed on the cut ends due to 6. In seeds, they cause expansion of cotyledons.
which these cuttings develop into successful 7. They inhibit apical dominance.
plants. 8. They help in promotion of chlorophyll
5. In apples, tomatoes and bananas auxins can synthesis in chloroplasts and organ formation.
induce fruit formation without fertilization
which is called Parthenogenesis . 3.4 Ethylene
6. In pineapple, auxin promotes flowering. Ethylene is a simple gaseous hormone which
7. In lettuce, auxins help in delaying the stimulates transverse growth. It is produced in
flowering. higher plants and fungi. Most widely used plant
8. In cotton plants, auxin increases the cotton growth hormone in agriculture.
seed production. Physiological Effects on Plants :
The Physiological effects on plants are as follows :
3.2 Gibberellins
1. Ethylene retards flowering in most plants but
Gibberellins were first reported in Japan by E induces flowering in pineapple and mango.
Kurosawa (1926). Unlike auxins, they enhance 2. In banana, apple, mango and citrus ethylene
longitudinal growth of stem when applied to the stimulates ripening of fruits.
plants. 3. Ethylene modifies growth by inhibiting the
Physiological Effects on Plants : elongation of stems and roots. In stem, it
1. Gibberellins promote seed germination in causes swelling of nodes.
cereals and lettuce. 4. Ethylene breaks dormancy of buds and seeds.
2. In pea, bean, tomato and cabbage on 5. It initiates germination in peanut seeds,
treatment with gibberellins they develop sprouting of potato tuber and induces
broader and elongated leaves. flowering in mango.
3. They are more potent parthenocarpic agents
than auxins. 3.5 Abscisic Acid (ABA)
4. Gibberellins causes stem elongation and leaf Abscisic acid is a natural growth inhibitor which
expansion but have no effect on roots. retards growth. It is found in angiosperms,
5. In cabbage, internodes are reduced. Just prior gymnosperms, pteridophytes and some mosses.
to flowering internode elongates enormously. Fruits and seeds contain highest amount of ABA.
This is called Bolting. By application of It is also called stress hormone since it increases
gibberellins bolting can be induced artificially. tolerance of plants to various kinds of stresses.
6. They are used to increase fruit size and bunch Physiological Effects on Plants :
in grapes. The Physiological effects on plants are as follows :
7. Gibberellins break dormancy of buds and 1. Abscisic acid inhibits cell division and cell
tubers. elongation. Acts as a general plant growth
inhibitor.
CH 6 : CHEMICAL COORDINATION IN PLANTS
Ans : MAIN 2001
The growth of the pollen tube towards the ovule
Cytokinin is the plant hormone responsible is an example of chemotropism. This is because
for inducing morphogenesis during plant the movement is guided by chemical signals
tissue culture. It promotes cell division and released from the ovule, which attract the pollen
differentiation, leading to the development of tube. The pollen tube grows in response to these
shoots and roots from undifferentiated plant chemical stimuli, allowing fertilization to occur.
tissues. In plant tissue culture, a balance between Chemotropism specifically refers to growth or
auxins and cytokinins determines whether root or movement in response to chemical signals.
shoot formation occurs, with cytokinin playing a Thus (d) is correct option.
key role in shoot development.
Thus (c) is correct option. 32. Rohit wants to measure the growth in length of a
plant for his project. The device used for this is:
29. The roots of a plant are (a) Sphygmomanometer
(a) positively geotropic but negatively phototropic (b) Manometer
(b) positively phototropic but negatively (c) Auxanometer
geotropic (d) None of these
(c) negatively hydrotropic but positively Ans : MAIN 2023
phototropic
(d) positively phototropic but negatively Auxanometer is used to measure the growth
geotropic in length of a plant organ, there are two types
of auxanometer. i.e. Arc auxanometer and
Ans : SQP 2003
Pfeffer's auxanometer (automatic auxanometer).
The roots of a plant grow towards gravity, which Auxanometers can measure plant growth in
makes them positively geotropic. They also response to a variety of parameters, including
grow away from light, making them negatively temperature, sunlight and water conditions.
phototropic. This is a characteristic adaptation Thus (c) is correct option.
that allows roots to grow deeper into the soil
to access water and nutrients while avoiding 33. Mohit observed that the leaves of a Mimosa plant
exposure to light. fold when touched. He wonders what external
Thus (a) is correct option. stimulus causes this reaction. The leaves of
Mimosa are sensitive to:
30. A higher concentration of ethylene is found in: (a) Heat (b) Touch
(a) ripe banana (c) Light (d) Smell
(b) green banana Ans : COMP 2015
(c) fresh potato tuber
(d) green apple The leaves of Mimosa have the capability to
display thigmonasty (touch-induced movement).
Ans : MAIN 2014
In the sensitive plant, the leaves respond to being
A higher concentration of ethylene is found in ripe touched, shaken, heated or rapidly cooled. The
banana because ethylene is a plant hormone that speed of the response depends on the magnitude
promotes the ripening of fruits. As bananas ripen, of the stimulus.
they produce more ethylene, which accelerates Thus (a) is correct option.
the ripening process. Ethylene acts as a signaling
molecule, triggering the biochemical changes 34. Rina is studying plant hormones and is curious
that cause the fruit to soften, change color, and about which one promotes plant growth. She
become sweeter. In contrast, green bananas and learned that certain hormones either inhibit or
other unripe fruits have lower levels of ethylene. promote growth. The hormone that functions as
Thus (a) is correct option. a growth promoter is:
(a) Abscisic acid
31. Growth of pollen tube towards the ovule is an (b) Ethylene
example of______. (c) Auxin
(a) phototropism (b) geotropism (d) Both b and c
(c) hydrotropism (d) chemotropism Ans : COMP 2017
Ans : COMP 2011
Plant growth promoter hormones are those plant
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 193

3. Which of the following shows thigmonastic In 1928, Dutch botanist Fritz W. Went finally
response ? isolated auxin diffused out from the tip of oat
(a) Insectivorous plants coleoptiles in the gelatin block.
(b) Sun flower Thus (b) is correct option.
(c) Lotus
(d) Bryophyllum 8. A higher concentration of ethylene is found in :
(a) Ripe banana
Ans : SQP 2013
(b) Green banana
In conclusion, insectivorous plants, such as the (c) Fresh potato tuber
Venus flytrap, pitcher plants, sundews, and (d) Green apple
bladderworts, exhibit thigmonastic responses as Ans : MAIN 2004
part of their predatory behavior.
Thus (a) is correct option. Because ethylene is Gasous in state which helps
banana to ripen faster that is main work of this
4. Growth of pollen tube towards the ovule is an hormone is to support the ripening of fruits.
example of ______ . Thus (a) is correct option.
(a) phototropism
(b) geotropism 9. In tropic movements, plant parts move
(c) hydrotropism (a) away from the stimulus
(d) chemotropism (b) either towards or away from the stimulus
(c) only towards water
Ans : MAIN 2005
(d) towards the stimulus
Thus (c) is correct option. Ans : SQP 2020

5. The hormone that promotes ripening of fruits There are exceptions though as in Nastic movement
is______. where the tropism exhibited is independent of the
(a) cytokinin direction of the stimulus.
(b) ethylene Thus (d) is correct option.
(c) gibberellin
(d) auxin 10. Auxins are abundantly produced in :
(a) meristematic region of the shoot
Ans : COMP 2002
(b) base of the root
Ethylene is a gaseous plant hormone that causes (c) base of the shoot
the ripening of fruits. It is synthesized in a large (d) shoot
amount in the fruits and tissues undergoing Ans : COMP 2000
ripening and senescence, respectively. Ethylene is
commonly used in agricultural practice. Auxins are produced abundantly in the
Thus (b) is correct option. meristematic region of the shoot.
Thus (a) is correct option.
6. What are Plant hormones called ?
(a) Hypohormones 11. Which one of the following plant hormones is
(b) Phytohormones responsible for phototropism in plants?
(c) Metahormones (a) Cytokinin
(d) Cytohormones (b) Auxin
(c) Ethylene
Ans : SQP 2006
(d) Gibberellins
Thus (b) is correct option. Ans : MAIN 2004

7. Auxins were discovered by: The hormones responsible for phototropism are
(a) Darwin auxins. Bending of the plant is caused by more
(b) F.W.Went elongation of the shaded part as compared
(c) Boysen - Jensen to the lighter side, caused by increased auxin
(d) None of these concentration on shaded side and decreased on
the other side.
Ans : SQP 2010
Thus (b) is correct option.
CH 6 : CHEMICAL COORDINATION IN PLANTS

2. It increases resistance in plants to cold. negatively hydrotropic as it grows away from

3. In plants subjected to salinity or under the source of water.
severe drought, abscisic acid reduces the rate 4. Thigmotropism : Growth movements made
of transpiration by temporarily closing the by plants in response to contact (touch)
stoma. with a solid object are called thigmotropism.
4. It induces bud dormancy in many plants. These are curvature movements and are most
5. In Ivy and bean, it promotes rooting of stem apparently seen in tendrils and twiners. Plants
cuttings. such as bitter gourd, bottle gourd, grapevine
6. It inhibits seed germination, stimulates closure and passion flower have stem tendrils which
of stomata and helps seeds to withstand are positively thigmotropic. Plants such as
desiccation. peas and glory lily have leaf tendrils which
are positively thigmotropic.
4. MOVEMENT IN PLANTS 5. Chemotropism : The tropic movement in
Plants show movement in response to certain response to the stimulus of the chemicals
stimuli like - light, water, gravity, wind and touch. are called Chemotropic movements. Growth
Some of the plant movements that is usually of pollen tube through the style towards the
observed are as follows: embryo sac, movement of pollen tube towards
Opening and closing of stoma, flower closing ovary due to absorption of calcium and borate
during night, sunflower turns toward the sun, from style of carpel, movement of tentacles in
movement of insectivorous plants and movement Drosera, an insectivorous plant, closing of lid
of roots in the soil. These movements can be of Nepenthes, an insectivorous plant, due to
divided into two categories: nitrogenous food, movement of fungal hyphae
(A) Tropic movements (Tropism) towards sugars and peptones and penetration
(B) Nastic movements [Not in Syllabus] of haustoria of parasite into host body all are
examples of chemotropism.
4.1 Tropic movements (Tropism)
A tropism is the movement of part of a plant
either towards the source of stimulus (Positive)
or away from it (Negative). Depending upon the MULTIPLE CHOICE QUESTION
nature of stimuli these movements are of following
five types:
1. Phototropism : The movement of plant parts in 1. A sunflower plant bends towards the sun. It is
response to light is called phototropism. Most ______response.
of the stems and flower stalks moves towards (a) Thigmonastic
light (positively phototropic). Roots move (b) Photonastic
away from light (negatively phototropic).The (c) Thermonastic
leaves keep their faces at right angles to the (d) Seismonastic
direction of light (transversly phototropic). Ans : MAIN 2017
2. Geotropism : The movement of plant parts
One of the best characterized growth responses in
in response to the force of gravity is called
plants is phototropism.
Geotropism. The primary root always grow
Thus (b) is correct option.
vertically towards downward direction
towards the force of gravity (positively 2. Which of the following is a plant hormone?
geotropic).Shoot moves just opposite to the (a) Thyroxine (b) Insulin
force of gravity (negatively geotropic). (c) Oestrogen (d) Cytokinin
The secondary roots and branches place
themselves at right angles to the force of Ans : SQP 2010

gravity and are called diageotropic. Examples Cytokinin is a plant hormone. Insulin is an animal
are Rhizome and stolon. hormone. Oestrogen is an animal hormone.
3. Hydrotropism : The movement of plant parts in Cytokinins promote cell division, and are present
response to the water is called Hydrotropism. in greater concentration in areas of rapid cell
Roots are positively hydrotropic as they division, such as in fruits and seeds.
bend towards the source of water. Shoots are Thus (d) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 195

Phototropism is a response to the stimulus of 24. Apical dominance phenomenon is caused by :

light. It can either be towards the source of light (a) ABA (b) GA
(positive phototropism) or away from it (negative (c) cytokinins (d) auxins
phototropism).
Ans : COMP 2017
Thus (a) is correct option.
Apical dominance in plants refers to the condition
20. The hormone that promotes ripening of fruits is where the apical bud is prominent hence keeping
______. the central stem dominant. It doesn't allow the
(a) ethylene proliferation of lateral buds. It is caused due to
(b) gibberellin production of auxin in the apical bud. This results
(c) cytokinin in prevention of growth of lateral buds in plants
(d) auxin Thus (d) is correct option.
Ans : COMP 2002
25. A plant’s response to light is known as
Ethylene is a gaseous plant hormone that causes (a) phototropism
fruit to mature. It is abundantly synthesised in (b) hydrotropism
the fruits and tissues undergoing ripening and (c) photonasty
senescence, respectively. Ethylene promotes the (d) geotropism
ripening of fruits such as tomatoes, lemons, and
Ans : MAIN 2000
oranges.
Thus (a) is correct option. The movement of a plant part in response to light
is called phototropism.
21. Auxin inhibits the growth of Thus (a) is correct option.
(a) apical buds
(b) root on stem cuttings 26. A plant hormone related with inhibition of
(c) lateral axillary buds senescence is :
(d) parthenocarpic development of fruits (a) Ethylene (b) GA
(c) Bromic acid (d) ABA
Ans : SQP 2008
Ans : COMP 2020
Auxin inhibits the growth of lateral axillary buds.
Thus (c) is correct option. Plant senescence refers to ageing in plants. The
hormone which is responsible for the inhibition of
22. Common gibberellin is ______ senescence is GA.
(a) GA1 (b) GA2 Thus (d) is correct option.
(c) GA7 (d) GA3
27. Leaf fall occurs when the amount of______.
Ans : SQP 2003 (a) auxin increases
Gibberellic acid is a plant hormone that (b) cytokinine decreases
stimulates plant growth and development. GA3 (c) abscisic acid increases
is the most common gibberellin because it is the (d) gibberellin decreases
main component in Gibberella culture and it is Ans : SQP 2018
the most frequently produced GA.
Thus (d) is correct option. Leaf abscission is a detachment or fall of older
leaves. It occurs at the base of the petiole. It
23. Leaf fall occurs when the amount of ______. is observed that the intact leaf does not fall off
(a) auxin increases because base of petiole of young leaf synthesizes
(b) cytokinine decreases auxin. During leaf fall, auxin content is low in
(c) gibberellin decreases the lamina as compared to stem. Also, ethylene
(d) abscisic acid increases content is high in the lamina during abscission.
Thus (c) is correct option.
Ans : MAIN 2010

Leaf fall occurs in a tree when there is increase in 28. A plant hormone responsible for inducing
concentration of. DAbscisic acid. morphogenesis during plant tissue culture is
Thus (d) is correct option. (a) ethylene (b) gibberellin
(c) cytokinin (d) abscisic acid
CH 6 : CHEMICAL COORDINATION IN PLANTS

DIRECTION : Matching Type Question : Identify the correct pair of hormones.

(a) P – Gibberellins, Q – Abscisic Acid
40. Riya is trying to match plant hormones with their (b) P – Cytokinins, Q – Auxins
physiological effects. She tabulated the pairs as (c) P – Ethylene, Q – Auxins
follows: (d) P – Auxins, Q – Gibberellins
Hormone Effect on the plant Ans : SQP 2014

P Promotes the germination of seeds Ethylene promotes flowering in pineapple, while

in cereals and lettuce auxins can induce parthenogenesis, which is the
Q Inhibits seed germination and formation of fruit without fertilization in plants
promotes stomatal closure like tomatoes.
Thus (c) is correct option.
Identify the correct pair of hormones.
(a) P – Gibberellins, Q – Abscisic Acid 43. Nisha made a table to match plant hormones with
(b) P – Auxins, Q – Ethylene their roles in plant physiology:
(c) P – Cytokinins, Q – Auxins
(d) P – Ethylene, Q – Gibberellins Hormone Effect on the plant

Ans : COMP 2007

P Promotes seed dormancy

Gibberellins promote seed germination, especially Q Induces bolting in cabbage before

in cereals and lettuce, while Abscisic acid (ABA) flowering
inhibits seed germination and promotes the Identify the correct pair of hormones.
closure of stomata during water stress. (a) P – Abscisic Acid, Q – Gibberellins
Thus (a) is correct option. (b) P – Cytokinins, Q – Auxins
(c) P – Auxins, Q – Gibberellins
41. Priya is matching plant hormones with their (d) P – Gibberellins, Q – Cytokinins
effects on the plant. She created the following
table: Ans : COMP 2010

Abscisic acid (ABA) is known to promote seed

Hormone Effect on the plant
dormancy, while gibberellins induce bolting in
P Promotes apical dominance in plants cabbage before flowering, leading to rapid stem
Q Delays the aging of leaves and elongation.
other organs Thus (a) is correct option.

Identify the correct pair of hormones. 44. Raj is matching hormones with their functions in
(a) P – Auxins, Q – Cytokinins plants and prepared the following pairs:
(b) P – Ethylene, Q – Gibberellins
Hormone Effect on the plant
(c) P – Abscisic Acid, Q – Cytokinins
(d) P – Cytokinins, Q – Auxins P Causes swelling of nodes and
inhibits stem elongation
Ans : MAIN 2002
Q Breaks bud dormancy and
Auxins promote apical dominance by inhibiting promotes leaf expansion
the growth of lateral buds, while cytokinins delay
the aging process in plant organs like leaves by Identify the correct pair of hormones.
promoting cell division and protein synthesis. (a) P – Gibberellins, Q – Cytokinins
Thus (a) is correct option. (b) P – Ethylene, Q – Gibberellins
(c) P – Cytokinins, Q – Ethylene
42. Rakesh is identifying hormones based on their (d) P – Abscisic Acid, Q – Gibberellins
effects on plants. He has made the following table: Ans : MAIN 2006

Hormone Effect on the plant Ethylene inhibits stem elongation and causes
P Promotes flowering in pineapple swelling of nodes in plants. Gibberellins break
bud dormancy and promote leaf expansion in
Q Induces fruit formation without
many plant species.
fertilization in tomatoes
Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 197

hormones that help in the growth of plants. plant respond to stress conditions like drought,
Example: auxins, gibberellins, etc. salinity, and cold. It induces the closure of stomata
Thus (c) is correct option. to reduce water loss through transpiration and
promotes dormancy in seeds and buds to help the
35. Arjun noticed that the mature leaves and fruits plant survive unfavorable conditions.
of a plant were falling off and wanted to know Thus (b) is correct option.
which hormone was responsible for this process.
The plant hormone triggering the fall of mature 38. Reema is studying plant movements and wants to
leaves and fruits from plants is: identify which of the following is not an example of
(a) auxin tropism. Which of the following are not tropism?
(b) gibberellin (a) Growth of pollen tube towards sugary
(c) kinetin substance.
(d) abscisic acid (b) Twining of tendrills around a support in
response to touch
Ans : COMP 2008
(c) Folding up of the leaves of Mimosa pudica
The falling of mature leaves and fruits from plants when touched.
is called abscission. It is caused by a hormone (d) None of the above
called abscisic acid. This hormone inhibits a
plant's growth by acting against growth-promoting Ans : SQP 2020

hormones. (a) Growth of the pollen tube towards a sugary

Thus (d) is correct option. substance is an example of chemotropism,
which is a tropic movement in response to a
36. Priya is conducting an experiment on plant tissue chemical stimulus.
culture. She adjusts the hormone levels and (b) Twining of tendrils around a support
observes how different ratios of auxin to cytokinin in response to touch is an example of
affect plant growth. She wonders what a high thigmotropism, which is a directional
auxin to cytokinin ratio will favor. A High auxin movement towards a physical object.
to cytokinin ratio favours the (c) Folding up of the leaves of Mimosa pudica
(a) shoot development when touched is an example of nastic
(b) formation of undifferentiated cells movement, not tropism. Nastic movements
(c) root development are responses to stimuli that do not depend
(d) None of the above on the direction of the stimulus.
Ans : MAIN 2001 Thus (c) is correct option.
It is well established that the auxin-cytokinin 39. Ravi noticed that his houseplant was growing
ratio used in culture media determines the degree toward the window where sunlight was coming in
of shoot and/or root formation in tissue culture. and wondered what this type of growth is called.
A high ratio of cytokinin to auxin favours shoot The growth of plants in the direction of light is
production, whereas a high auxin to cytokinin called:
ratio favours root production. (a) phototropism
Thus (c) is correct option. (b) geotropism
(c) chemotropism
37. During his plant physiology studies, Arjun learned
(d) hydrotropism
that certain hormones help plants cope with stress
conditions like drought. He is now trying to figure Ans : SQP 2002
out which one is known as the stress hormone. Phototropism is the growth of plant parts, such
The stress hormone is as stems or leaves, in response to light. In positive
(a) auxin phototropism, the plant grows toward the light
(b) abscisic acid source, as seen in most stems and shoots. This
(c) ethylene helps the plant maximize its ability to perform
(d) cytokinin photosynthesis. Other forms of tropism like
Ans : SQP 2003 geotropism respond to gravity, and chemotropism
responds to chemicals.
Abscisic acid (ABA) is often referred to as the
Thus (a) is correct option.
stress hormone in plants because it helps the
CH 6 : CHEMICAL COORDINATION IN PLANTS

12. The plant hormone used to speed up the malting towards any support they come in contact with,
process in brewing industry is and winding around them for support, is an
(a) ethylene (b) GA3 example of thigmotropism. Thigmotropism is
(c) auxin (d) cytokinin the movement or growth of a plant in response
to touch or physical contact with a solid object.
Ans : SQP 2009
This response helps climbing plants to anchor
Gibberellins are used to speed up the malting themselves and grow upward by wrapping around
process in brewing industry. They increase the structures for support.
yield of malt from barley grains. Thus (d) is correct option.
Thus (b) is correct option.
16. Which of the following hormones regulate
13. During his biology class, Anil was learning stomatal closure :
about different hormones in plants and animals. (a) auxins (b) ABA
He wanted to identify which of the following (c) GA (d) cytokinin
is specifically a plant hormone. Which of the
following is a plant hormone? Ans : SQP 2016

(a) Adrenaline In guard cells, the plant hormone abscisic acid

(b) Glucagon (ABA) inhibits stomatal opening and induces
(c) Cytokinin stomatal closure through the coordinated
(d) Oxytocin regulation of ion transport.
Thus (b) is correct option.
Ans : MAIN 2019

Cytokinin is a plant hormone. Insulin is an animal 17. Both ethylene and ABA are responsible for
hormone. Oestrogen is an animal hormone. (a) inducing dormancy of seeds
Cytokinins promote cell division, and are present (b) stimulation of apical dominance
in greater concentration in areas of rapid cell (c) ripening of fruits
division, such as in fruits and seeds. (d) promoting abscission of leaves and fruits
Thus (c) is correct option. Ans : MAIN 2004

14. Stems are : Ethylene and ABA hormones accelerate the

(a) positively geotropic and negatively process of senescence.
phototropic Thus (d) is correct option.
(b) positively geotropic and positively phototropic
(c) negatively phototropic and negatively 18. When roots of a plant always move towards water,
geotropic even if it means going against the pull of gravity
(d) negatively geotropic and positively This indicates
phototropic (a) hydrotropism
(b) negative geotropism
Ans : SQP 2022
(c) geotropism
Stems grow away from the roots and exhibits (d) positive geotropism
tropic movement in the direction where there is Ans : SQP 2023
sunlight.
Thus (d) is correct option. Hydrotropism modifies root growth to respond
to a water potential gradient in soil and grow
15. The climbing organs of plants like tendrils grow towards areas with a higher moisture content.
towards any support which they come in contact Thus (a) is correct option.
of and wind around them for support. This is an
example of 19. The growth of plants in the direction of light is
(a) chemotropism called ______.
(b) nastic movements (a) phototropism
(c) geotropism (b) geotropism
(d) thigmotropism (c) chemotropism
(d) hydrotropism
Ans : COMP 2017
Ans : MAIN 2009
The growth of climbing organs like tendrils
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 199

DIRECTION : Conversation Type Question (a) Raj and Sonu

(b) Sonu and Abhay
45. A biology teacher asked her students to name two (c) Lata and Raj
types of plant movements in response to external (d) Abhay and Lata
stimuli. Ans : MAIN 2006
Raj said: Phototropism and Geotropism
Cytokinins delay the aging process in plant organs.
Sonu said: Hydrotropism and Chemotropism
Auxins also promote growth, and hence, together
Lata said: Thigmotropism and Nastic Movements
with cytokinins, they help delay senescence.
Abhay said: Phototropism and Hydrotropism
Ethylene and abscisic acid are growth inhibitors,
Who were correct?
not involved in delaying aging.
(a) Raj and Sonu
Thus (b) is correct option.
(b) Sonu and Abhay
(c) Lata and Abhay 48. A teacher asked her students to name two plant
(d) Raj and Lata hormones that help in breaking seed dormancy.
Ans : SQP 2003 Raj said: Abscisic Acid and Ethylene
Sonu said: Gibberellins and Ethylene
Phototropism, geotropism, hydrotropism,
chemotropism, and thigmotropism are plant Lata said: Auxins and Cytokinins
movements in response to different external Abhay said: Gibberellins and Cytokinins
stimuli. Nastic movements are not included in the Who were correct?
syllabus. Sonu and Abhay gave correct examples (a) Raj and Sonu
of plant movements. (b) Sonu and Abhay
Thus (b) is correct option. (c) Raj and Lata.
(d) Lata and Abhayl
46. A biology teacher asked her students to name two
Ans : SQP 2000
natural auxins found in plants.
Raj said: Indole Acetic Acid (IAA) and Indole Gibberellins and ethylene are involved in breaking
Butyric Acid (IBA) seed dormancy. Abscisic acid promotes dormancy,
Sonu said: 2, 4-D and IAA while auxins and cytokinins are more involved in
Lata said: Naphthalene Acetic Acid (NAA) and growth promotion rather than breaking dormancy.
IBA Thus (b) is correct option.
Abhay said: IAA and IBA 49. A biology teacher asked students to name two
Who were correct? phytohormones responsible for inducing fruit
(a) Raj and Abhay ripening.
(b) Sonu and Lata Raj said: Ethylene and Cytokinins
(c) Raj and Lata Sonu said: Ethylene and Gibberellins
(d) Sonu and Abhay
Lata said: Ethylene and Auxins
Ans : COMP 2011 Abhay said: Auxins and Gibberellins
Indole Acetic Acid (IAA) and Indole Butyric Acid Who were correct?
(IBA) are natural auxins found in plants. 2, 4-D (a) Raj and Lata
and NAA are synthetic auxins. Thus, Raj and (b) Sonu and Raj
Abhay gave correct examples of natural auxins. (c) Lata and Sonu
Thus (a) is correct option. (d) Abhay and Lata
Ans : COMP 2009
47. A biology teacher asked students to name two
hormones responsible for delaying the aging Ethylene is the main phytohormone responsible
process in plants. for inducing fruit ripening. Gibberellins may
Raj said: Cytokinins and Gibberellins have a role in promoting growth, but auxins
Sonu said: Auxins and Cytokinins and cytokinins do not play a direct role in fruit
Lata said: Ethylene and Abscisic Acid ripening.
Thus (c) is correct option.
Abhay said: Cytokinins and Auxins
Who were correct?
CH 6 : CHEMICAL COORDINATION IN PLANTS

84. List any four functions of Phytohormones. the unequal dtstribution of auxin on the two
sides of roots.
Ans : SQP 2019

1. Flowering of plants 90. One rotten orange can spoil the whole basket full
2. Ripening of fruits of oranges. Give reason.
3. Germination of seeds Ans : MAIN 2020
4. Stomatal movement in leaves.
The ripening of orange is caused by hormone
85. Explain briefly apical dominance. Name the ethylene. Ethylene is a gas, through diffusion it
hormone that controls it. passes from one orange to another. So it starts
spreading from one orange to another and slowly
Ans : MAIN 2023
all oranges in basket gets spoilt.
The apical buds grow and lower axillary buds
are suppressed. Removal of apical buds results 91. Define:
in growth of lower buds. This is called apical (i) Phototropism.
dominance. The hormone is Auxin. (ii) Hydrotropism.

86. What is Bolting ? Give an example. Ans : COMP 2023

(i) The movement of plant organs towards

Ans : SQP 2010
the stimulus of light is photo tropism, e.g.
Just prior to flowering, internode elongates bending of stem towards light.
enormously. This is called bolting. e.g., Cabbage. (ii) The movement of plant parts towards water,
e.g. growth of roots towards water.
87. Auxins and Gibberellins induce growth in plants.
Which hormone has inhibitory effect on growth ? 92. Sunflower head point towards the sun. Explain.
Ans : MAIN 2008 Ans : MAIN 2009

Ethylene has inhibitory effect on elongation of In the presence of light, auxin hormone gets
stem and root. concentrated on the shaded part of sunflower
stem which causes growth on one side making a
88. Mention any two advantages of senescence.
curvature of the plant towards the lighted side
Ans : MAIN 2014 (sun).
1. Old and inefficient organs are replaced by
young and developing leaves, buds, flowers
and fruits.
2. In trees, when the old leaves are shed , THREE MARKS QUESTIONS
nutrients are withdrawn into main trunk and
diverted to the young parts later on.
93. State the physiological effects of auxin.
89. Study the figure and answer the following. Ans : MAIN 2016

Auxin hormone is usually seen at the growing

region. It promotes stem elongation, phototropism,
growth of roots, development of fruits etc.

94. State the effects of cytokinin and auxin.

Ans : MAIN 2002

Cytokinin stimulates cell division, germination of

(i) What is depicted in the figure? seeds, promotes root growth.
(ii) Explain the process. Auxin promotes stem elongation, growth of roots
Ans : SQP 2017 etc.
(i) Geotropism. 95. Ali has some pea plants in his garden which need
(ii) The movement of roots of the plants towards a support to grow as seen in the picture given
gravity is called geotropism. This is caused by below:
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66. What is Parthenocarpy ? Give one example. 76. Movement of fungal hyphae towards______
and peptones is called chemotropism.
Ans : COMP 2019

Development of fruit without fertilization. e.g., Ans : COMP 2015

Apple, banana, tomato. Sugars

77. ______are situated below the bark and are

DIRECTION : Fill up the blanks with suitable words: responsible for increase in the diameter of the
stem.
67. Gibberellins are widely used in______
and______. Ans : MAIN 2011

Lateral meristems
Ans : SQP 2005

Horticulture ; food industries 78. The phenomenon of development of seedless fruit

without fertilization is called______.
68. Cytokinins have specific effects on______.
Ans : SQP 2013
Ans : COMP 2004
Parthenocarpy
Cell division
79. A universal flowering hormone still not been
69. Roots of cycas plant do not respond to geotropic isolated by scientists is______.
stimulus. They are called______.
Ans : MAIN 2017
Ans : MAIN 2010
Florigen
Ageotropic
80. Auxins were isolated initially from the urine
70. Plant roots exhibit______tropism. of humans who suffered from a disease called
Ans : COMP 2018 ______.
Geotropism. Ans : COMP 2008

Pellagra
71. ______plant hormone is a gas.
Ans : SQP 2008

Ethylene TWO MARKS QUESTIONS

72. ______hormone stimulate germination of
seeds. 81. Which parts of a plant exhibit:
(a) Negative Geotropism
Ans : MAIN 2016
(b) Positive Hydrotropism
Cytokinin
Ans : SQP 2025

73. The movement of plant parts towards the stimulus (a) Shoot, (b) Root
of chemical is______.
82. How does chemical coordination occur in plants ?
Ans : COMP 2023
Ans : MAIN 2012
Chemotropism.
Chemical coordination in plants are occurred in
74. The first step in the process of plant growth plants with the help of fluids secreted in plants
is______germination. known as phytohormones or plant hormones.
Ans : MAIN 2018
These hormones regulate the growth of the plants.

Seed 83. What is the full form of: IAA, NAA and IBA ?

75. A plant hormone is an______substance. Ans : COMP 2015

Ans : SQP 2020

IAA - Indole acetic acid
NAA - Naphthalene acetic acid
Organic IBA - Indole butyric acid
CH 6 : CHEMICAL COORDINATION IN PLANTS

the style towards the ovule. FIVE MARKS QUESTIONS

(iii) A – Pollen grain B – Pollen tube
C – Female gamete D – Ovary
104. Given below is an experimental setup to
102. Study the figure and answer the following. demonstrate a particular tropic movement in
(i) What is depicted in the figure? germinating seeds. Study the diagram and answer
the questions that follow :

(i) Label the parts 1 and 2.

(ii) Name the tropic movement shown by part 1.
(iii) Part 1 is affected by two stimuli. Name them.
Which one of the two is stronger ?
(ii) Define the process. (iv) What is Thigmotropism ? Give one example.
(iii) How does the plant move towards the light? (v) What is meant by ‘Positive’ and ‘Negative’
tropic movements in plants ?
Ans : SQP 2014

(i) Phototropism. Ans : COMP 2022

(ii) The movement of shoots towards light. (i) 1-Radicle 2-Plumule

(iii) This is due to the synthesis of auxin hormone (ii) Hydrotropism
at the shoot tip .In the presence of light, (iii) Gravity and Water - Water is stronger.
auxin accumulate on the shaded part of the (iv) Growth movement of plants in response to
stem causes growth on one side causing a touch stimulus, e.g., Sweet Pea.
curvature towards the lighted side. (v) Movement of parts of plant towards source of
stimulus is positive and away from source of
103. The diagram given below is an instrument which stimulus is negative.
is used to eliminate the effect of gravity.
105. The diagram shows some movement in plants.
(i) What is the aim of the experiment?
(ii) Why does the plant move towards the light
source?
(iii) What is geotropism?
(iv) What are tropic movements?
(v) What will happen if the light source is
removed from the experiment?

(i) Name the instrument.

(ii) What is the use of this instrument in this
experiment?
(iii) Why does the plant grow straight?
Ans : MAIN 2015

(i) Clinostat.
(ii) If it rotates it neutralises the effect of gravity.
(iii) Due to equal distribution of auxin that causes
equal growth on all sides and no curvature
takes place.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 203
Ans : COMP 2019

This is due to the synthesis of auxin hormone

at the shoot tip .In the presence of light, auxin
accumulate on the shaded part of the stem causes
growth on one side causing a curvature towards
the lighted side.

100. Study the figure and answer the following:

(i) Name the phenomenon depicted by the shoot

in the given figure.
(ii) Define the above phenomenon.
(iii) Write the name of the part marked X. (i) What is X?
(ii) Explain the process which is being undertaken.
Ans : MAIN 2024
Ans : MAIN 2000
(i) Thigmotropism
(ii) The movement of plant parts in response to (i) Tendril
stimuli caused by contact with foreign body (ii) Thigmotropism: is the movement of tendril
is called thigmotropism. towards the stimulus of touch. The tendrils
(iii) Stem tendril twin around the support due to the
accumulation of auxin
96. Give example of the following:
(i) Chemotropism 101. The figure represents an example of a plant
(ii) Thigmotropism movement. Study it and answer the following:
(iii) Phototropism
Ans : COMP 2021

(i) Growth of pollen tube towards the ovule.

(ii) Growth of tendril around a support.
(iii) Growth of stem towards light.

97. Demonstrate an experiment to prove hydrotropism.

Ans : SQP 2003

Take a conical flask with water. Cover the neck of

the flask with a wire mesh. Keep a few germinated
bean seeds on it. After a few days it is observed
that the primary roots of the seeds towards water
in the flask and the shoots towards light.

98. Though plants do not have a nervous system, yet

they perform all physiological activities comment. (i) What is shown in the figure?
(ii) Define the process.
Ans : COMP 2004 (iii) Mark the parts A, B, C and D.
It is true that plants do not have a nervous system, Ans : COMP 2006
yet they perform their various activities by
hormones which include both growth promoters (i) Chemotropism.
and inhibiters. (ii) The movement of plant organs in response to
chemicals. The sugar present in the stigma
99. Give reason: Stem of a plant grows towards light. stimulate the growth of pollen tube through
CH 6 : CHEMICAL COORDINATION IN PLANTS

ONE MARK QUESTIONS 58. Thigmotropism

Ans : MAIN 2004

DIRECTION : Arrange and rewrite the terms in the The movement of plant parts in response to touch.
group in the correct order so as to be in a logical
sequence beginning with the term that is underlined. 59. Ethylene.
Ans : SQP 2017
50. Apical meristem, Positive phototropism, Auxins,
Ethylene is a plant regulater that is a gas. It
Cell elongation.
promotes fruits ripening.
Ans : SQP 2025

Auxins, Apical meristem, Cell elongation, Positive DIRECTION : Answer the following.
phototropism
60. Which hormones inhibit growth?
DIRECTION : Name the following: Ans : COMP 2001

Abscisic acid and ethylene are growth inhibiters.

51. The tropic movement of plant parts in response
to chemicals. 61. Distinguish between thigmotropism and
Ans : MAIN 2024 geotropism.
Chemotropism Ans : MAIN 2009

52. A growth inhibiting hormone in plants. Thigmotropism Geotropism

Ans : MAIN 2019 The movement The movement of
of plant parts in plant parts towards
Abscisic acid
response to touch, e.g. the stimulus of
53. The hormone which stimulates cell division. growth of tendrils of gravity, e.g. growth of
pea plant. roots towards gravity.
Ans : COMP 2004

Cytokinin 62. Mention the physiological effects of gibberellin.

54. Directional movement of plants towards a Ans : SQP 2000
stimulus. Movement of plants towards the stimulus of light.
Ans : SQP 2006
63. The shoot of a plant usually shows phototropism
Tropic movement
Comment.
55. The hormone located at the apical meristem. Ans : MAIN 2010

Ans : COMP 2019 The movement of plant organs especially the

shoot towards the direction of light is called
Auxin.
phototropism. Under the influence of light, more
amount of auxin is produced to the shaded side of
DIRECTION : Define the following :
the stem causing a curvature towards the lighted
side.
56. Growth
Ans : MAIN 2000 64. Expand the following biological abbreviations :
Ans : MAIN 2019
It is a vital process which brings about a
permanent change in the weight, size, volume of Adenosine triphosphate
a plant.
65. State the main functions of the following :
57. Tropic movement Cytokinins
Ans : COMP 2013 Ans : SQP 2019

The movement of plant parts in the direction of a Expansion of cotyledons, inhibits apical
stimulus such as light, gravity and touch. dominance, cell elongation.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 205
Ans : MAIN 2003 Ans : MAIN 2006

(i) To demonstrate phototropic movement.

(ii) Due to light the auxin gets destroyed and the (i) Auxins Gibberellins (Seed
plant bends towards light. dormancy)
(iii) The movement of plant parts in response to No effect Suppresses
the force of gravity. (ii) Auxins Cytokinins (Apical
(iv) It is the movement of part of the plant either dominance)
towards the source of stimulus or away from Promotes Inhibits
it.
(iii) Gibberellins Abscisic acid (Seed
(v) The plant will grow straight.
germination)
106. Give reasons for the following: Suppresses Induces
(i) Exogenous application of auxin fails to (iv) Auxins Abscisic acid
enhance growth in an intact plant. (Growth)
(ii) Gibberellic acid is able to induce reversal of Promotes Inhibits
dwarfism in many genetically dwarf plants.
(v) Thigmotropism Chemotropism
(iii) Rice plants infected by fungus Gibberella
(Example)
fugikuroi grow foolishly tall.
Touch stimulus Chemical stimulus
(iv) In pineapple, auxin is used.
(v) Abscisic acid is also called stress hormone. (vi) Auxins Cytokinins
(Scientist who
Ans : COMP 2018
discovered)
(i) Intact plants already have required amount of F.W.Went Skoog & Miller
auxin. Further application of auxin makes no (vii) Cuscuta Drosera (Type
effect. of tropic
(ii) In genetically dwarf plants, GA level is low movement shown)
but the external supply of GA to such plants Thigmotropism Chemotropism
causes rapid elongation in their height.
(iii) The fungus produces a growth hormone called (viii) IAA ABA (Full form)
gibberellins which causes abnormal growth of Indole acetic acid Abscisic acid
stem and leaves with long internodes, early
flowering or death before flowering in rice 108. The diagram shows an experiment on a type of
plants. tropic movement in plant.
(iv) In pineapple, auxin is used to promote
flowering.
(v) Abscisic acid is also called stress hormone
since it increases tolerance of plants to various
kinds of stresses. It is produced in response to
stress.

107. Differentiate between the following as indicated

in brackets :
(i) Auxins and Gibberellins (Seed dormancy)
(ii) Auxins and Cytokinins (Apical dominance)
(iii) Gibberellins and Abscisic acid (Seed
germination)
(iv) Auxins and Abscisic acid (Growth)
(v) Thigmotropism and Chemotropism
(movement of plants in response to) (i) What is the aim of the experiment?
(vi) Auxins and Cytokinins (Scientist who (ii) What is A and B ?
discovered) (iii) What is the observation of this experiment?
(vii) Cuscuta and Drosera (Type of tropic (iv) Why is the movement of A and B is in
movement shown) different directions?
(viii) IAA and ABA (Full form) Ans : SQP 2010
CH 6 : CHEMICAL COORDINATION IN PLANTS

(i) To demonstrate that plants show geotropism. 111. Students learned that plant growth regulators,
(ii) A-Shoot growing upward B-Root bending also called phytohormones, control plant
towards earth. growth. These hormones are divided into growth
(iii) The shoot will be found growing upwards promotors (Auxins, Gibberellins, Cytokinins)
after giving a curvature showing that it and growth inhibitors (Abscisic acid, Ethylene).
is negatively geotropic. The root grows The term "hormone" was introduced by William
downwards showing positive geotropism. Bayliss and Ernest Starling.
(iv) Due to unequal distribution of auxin. Answer the following questions:
1. What are plant growth regulators also called?
2. Who introduced the term hormone?
3. Name the three growth-promoting hormones
CASE BASED QUESTION in plants.
4. Which two hormones act as growth inhibitors
109. Students observed how growth in plants occurs in plants?
through cell division at meristems near the shoot Ans :
and root tips. They also learned that plants
1. Plant growth regulators are also called
respond to environmental changes like light and
phytohormones.
gravity through hormones, which control growth
2. The term hormone was introduced by William
without the need for a nervous system.
Bayliss and Ernest Starling.
Answer the following questions:
3. The three growth-promoting hormones
1. Where does cell division for growth mainly
in plants are Auxins, Gibberellins, and
occur in plants?
Cytokinins.
2. How do plants respond to changes without a
4. The two growth inhibitors in plants are
nervous system?
Abscisic acid and Ethylene.
3. What role do hormones play in plant growth?
4. Why don't plants need fast responses to small 112. In a plant biology class, students studied auxins,
environmental changes? a group of plant hormones produced in the root
Ans : and shoot tips. These hormones play a key role
in promoting cell elongation, fruit formation,
1. Meristems
and controlling apical dominance. Auxins can be
2. Hormones
either natural (IAA and IBA) or synthetic (2,
3. Growth
4-D and NAA) and have various effects on plant
4. Adaptation
growth and development.
110. Cytokinins Application-Based Case:In a plant lab, Answer the following questions:
students observed how cytokinins, in the presence 1. Where are auxins produced in plants?
of auxins, stimulated cell division and delayed 2. What is apical dominance, and how is it
ageing in leaves. They also noted that cytokinins controlled by auxins?
promoted chlorophyll synthesis and helped break 3. How can auxins be used to induce fruit
seed dormancy. formation without fertilization?
Answer the following questions: 4. Name two natural and two synthetic auxins.
1. How do cytokinins influence cell division? Ans :
2. In what way do cytokinins delay the ageing
1. Root and shoot tips
process in plants?
2. Apical dominance
3. How do cytokinins help promote chlorophyll
3. Parthenogenesis
synthesis?
4. IAA, IBA, 2, 4-D, NAA
4. What role do cytokinins play in seed
dormancy? 113. In a plant biology experiment, students applied
Ans : gibberellins to pea, bean, and tomato plants
and observed increased leaf elongation and stem
1. Cell division
growth. They also induced artificial bolting in
2. Anti-ageing
cabbage by applying gibberellins.
3. Chlorophyll synthesis
Answer the following questions:
4. Germination
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 207

1. What is the effect of gibberellins on seed 4. Stress

germination?
2. How do gibberellins induce bolting in cabbage 116. Students conducted an experiment on plant
plants? movements. They observed phototropism in
3. What is the role of gibberellins in fruit size in sunflower stems bending towards light, geotropism
grapes? in roots growing downward, and thigmotropism in
4. Can gibberellins promote root growth? tendrils of grapevine responding to touch.
Answer the following questions:
Ans : 1. What is phototropism, and how do sunflower
1. Germination stems respond to light?
2. Bolting 2. Describe the geotropism observed in roots in
3. Cell elongation response to gravity.
4. No 3. How does thigmotropism help tendrils in
climbing plants like grapevines?
114. In an agricultural study, students applied ethylene 4. What is hydrotropism, and how do roots
to bananas and observed rapid ripening. They respond to water?
also noticed that ethylene stimulated flowering in
pineapples and mangoes and broke dormancy in Ans :
potato tubers. 1. Phototropism
Answer the following questions: 2. Geotropism
1. How does ethylene affect the ripening of fruits 3. Thigmotropism
like bananas and mangoes? 4. Hydrotropism
2. What is the effect of ethylene on flowering in
pineapples? www.nodia.in
3. How does ethylene break dormancy in buds
and seeds?
4. Can ethylene inhibit stem elongation in
plants?
Ans :
1. Ripening
2. Flowering
3. Dormancy break
4. Yes

115. In a drought-stress experiment, students applied

abscisic acid to plants and observed the temporary
closure of stomata, reducing water loss. They also
noticed that ABA induced bud dormancy and
inhibited seed germination.
Answer the following questions:
1. How does abscisic acid help plants during
drought conditions?
2. What is the role of ABA in inducing bud
dormancy?
3. How does abscisic acid inhibit seed
germination?
4. Why is abscisic acid called the "stress
hormone"?
Ans :
1. Stomatal closure
2. Dormancy
3. Inhibition
CH 7 : THE CIRCULATORY SYSTEM

CHAPTER 7
THE CIRCULATORY SYSTEM

4. MYOGENIC HEART
SUMMARY
The heart which is the main pumping organ is
independent from the control of both nervous
1. COMPONENTS OF CIRCULATORY SYSTEM system and hormonal system. It is made-up of
strong cardiac muscles, and situated between
The main constituents of the circulatory system
two lungs in the thoracic cavity protected by the
in human body are heart and blood vessels, e.g.,
ribcage. There are four chambers in the heart.
artery, veins and capillaries by which the flow of
Two auricles and two ventricles. Artery is the
blood occurs and is maintained. Essentially the
blood vessel which carries oxygenated blood while
two functional components in the circulatory
vein carries deoxygenated blood. The ultimate
system are (i) blood vascular system and (ii)
branch of artery and veins are called arterioles
lymph vascular system. The activity of heart
and venules. The lymph travels in the lymphatic
consists in pumping of blood through the blood
vessels while there is tissue fluid which surrounds
vessels which in turn continue to maintain the
the cells. Lymph and tissue fluids are not red
flow of blood.
in colour due to absence of RBC (Red Blood
2. FUNCTIONS OF BLOOD Corpuscles).
Blood is a liquid connective tissue, which is red in 5. COMPARISON OF AN ARTERY WITH A VEIN AND
colour, salty in taste with pH 7.4. It is a viscous CAPILLARY
sticky fluid with a specific gravity 1.05 to 1.06.
The Comparison between artery with a vein and
The total quantity of blood in a full-grown human
capillary are as follows :
body is 4-6 litres. The main function of the blood
is to carry oxygen to different parts of the body Co-rison Artery Vein Capillary
as every living cell respires (cellular respiration)
Presence No Yes No
with the oxygen carried by Hemoglobin of the
of valves
blood. It removes unwanted excretory products
like carbon dioxide, urea and uric acid. It also Internal Fairly Fairly wide Very narrow;
distributes hormones and digested food materials diameter narrow; red blood
like amino acid, glucose and other dissolved food (lumen) can expand cells squeeze
(It is through
particles. It also protects our body from external
considered
germs. It is made-up of two principal components:
as pulse)
the fluid matrix which is called plasma and blood
cells called corpuscles suspended in the matrix.
Wall The wall is The wall is Wall is
3. CLOSED CIRCULATORY SYSTEM
structure relatively relatively composed
In all vertebrates including human beings the thick thin; there of a single
blood flows through the closed vessels like and also are valves cell layer;
arteries, veins and capillaries through a definite elastic, to to keep gaps between
route without coming in direct contact with body withstand blood cell allow
pressure. moving exchange of
cavity and space. This type of circulatory system
in one materials
is known as closed vascular system. direction. with
surrounding
tissues.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 209

Blood Blood flows Blood Blood flows valves guard the openings to the pulmonary artery
direction away from flows from arteries and the aorta to prevent backflow of blood into
the heart towards to veins the ventricles. Both valves have three semilunar
the heart (half moon-shaped) cusps.
Blood High Low Very low
pressure
Blood Rapid, Slow, Very slow
flow rate irregular regular

6. STRUCTURE OF THE HEART

The mammalian heart is composed mainly 6.2 Heart Disorders
of cardiac muscle : a specialize tissue that can In a heart attack, also called a myocardial
contract automatically, powerfully and without infarction, the blood flows to a particular
fatigue, throughout the life of the organism. part of the heart is blocked and that region of
It is important that blood flows through the heart myocardium (heart muscle) dies. The body can
in one direction only. Two sets of valves close to recover if only a small area of muscle dies, but
prevent back flow : extensive infarctions are often fatal.

7. TYPES OF HEARTBEAT
The heart continues to beat when removed from
the body. Individual heart muscle cells grown in
culture beat on their own. Because of this, we say
that vertebrate heart is myogenic : the stimulus
that drives it to beat originates in the muscle
itself. Some invertebrate hearts are neurogenic :
they beat only when connected to external nerves.
If a heart attack damages the conducting system
of the heart, the co-ordination of the heartbeat
can be disrupted. This condition is often called
a heart block. A patient with a permanent heart
block can be fitted with an artificial pacemaker.

8. CARDIAC CYCLE
The sequence of events in a single heartbeat is
6.1 The Atrioventricular Valves (AV valves) known as the cardiac cycle. The cycle involves
These lie between the atria and the ventricles to systole (or contraction) and also diastole (or
prevent blood from returning to the atria when relaxation) of the atria and ventricles. The cycle
the ventricles contract. The tricuspid valve on the has four overlapping stages.
right side has three cusps, or flaps. The bicuspid 1. Atrial systole : Both atria contract, forcing
valve, or mitral valve, on the left has two cusps. blood into the ventricles. This stage lasts 0.1
Both AV valves are subjected to great pressure seconds.
and ultra-tough tendinous cords are needed to 2. Ventricular systole : Both ventricles contract,
prevent them turning inside out. The semilunar forcing blood through the pulmonary artery
CH 7 : THE CIRCULATORY SYSTEM

The pericardium is a double-walled sac that Ans : MAIN 2000

encloses and protects the heart. It provides Blood enters the right atrium and passes through
lubrication to reduce friction between the heart the right ventricle. The right ventricle pumps the
and surrounding structures during heartbeats, blood to the lungs where it becomes oxygenated.
and it helps to anchor the heart in the chest Thus (c) is correct option.
cavity.
Thus (a) is correct option. 10. A doctor mentions that certain blood vessels
allow the exchange of gases and nutrients. The
6. The blood vessel that carries oxygenated blood exchange of gases, nutrients, etc. is done by:
is : (a) Capillaries, veins and arteries
(a) Pulmonary artery (b) Capillaries and arteries
(b) Pulmonary vein (c) Capillaries and veins
(c) Renal vein (d) Capillaries only
(d) Hepatic vein
Ans : COMP 2009
Ans : MAIN 2021
Exchange of Gases, Nutrients, and Waste Between
The pulmonary arteries carry deoxygenated Blood and Tissue Occurs in the Capillaries.
blood from the right ventricle to the lungs. The Capillaries are tiny vessels that branch out from
pulmonary veins carry oxygenated blood from the arterioles to form networks around body cells.
lungs to the left atrium. Thus (d) is correct option.
Thus (a) is correct option.
11. The opening of right auricle into the right ventricle
7. The nearest organ to which the heart supplies is guarded by
oxygenated blood is (a) Bicuspid valve
(a) Kidney (b) Tricuspid valve
(b) Heart (c) Aortic semi-lumar valve
(c) Lung (d) Pulmonary semi-lunar valve
(d) Intestine
Ans : SQP 2020
Ans : COMP 2021
The right atrioventricular opening is guarded by
The nearest organ to which the heart supplies the tricuspid valve, as it has three flaps.
oxygenated blood is a lung. Thus (b) is correct option.
Thus (b) is correct option.
12. Rate of heart beat is controlled by
8. A patient’s blood clotting is examined, and (a) Cranial nerves
it’s observed that a substance helps in the clot (b) SA node
formation by converting prothrombin to thrombin. (c) Sympathetic nerves
Thrombokinase is : (d) Spinal nerves
(a) an antibody Ans : SQP 2007
(b) an enzyme
Heart rate is controlled by the two branches of
(c) released by platelets
the autonomic (involuntary) nervous system.
(d) a waste product
The sympathetic nervous system (SNS) and the
Ans : SQP 2004 parasympathetic nervous system (PNS). The
Thrombokinase is an enzyme present in blood sympathetic nervous system (SNS) releases the
platelets and it converts prothrombin into hormones (catecholamines - epinephrine and
thrombin. The enzyme aids in the process of norepinephrine) to accelerate the heart rate.
blood clotting. Thus (b) is correct option.
Thus (c) is correct option.
13. Double circulation means
9. The chamber of heart which send deoxygenated (a) Oxygenated and deoxygenated blood is
blood to the lungs separated
(a) Right auricle (b) Left auricle (b) Every organ has an artery and a vein
(c) Right ventricle (d) Left ventricle (c) Blood flows twice through the heart
(d) Both (a) and (b)
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 211

4. Hb in cells does not increase the solute categorized as follows :

potential of the blood (free Hb would). (a) Agranular Leucocytes or Agranulocytes
Red blood cells have a very regular shape, described : Agranulocytes are the leucocytes whose
as a biconvex disc. When you think about what cytoplasm is not granular in appearance.
red blood cells do, it is easy to see why this is They are produced in the lymph nodes, spleen
a good shape for them. They must have a large and other lymphoid tissues. These are further
enough volume to carry useful amounts of oxygen of two types :
but they also need a large enough surface area to (i) Monocytes : They have the largest size
load and unload it quickly. The biconvex shape amongst leucocytes. A monocyte is a
is an efficient compromise between the maximum large amoeboid cell having a large kidney-
volume of a sphere and the maximum surface shaped nucleus.
area of a flat disc. Red blood cells are distorted (ii) Lymphocytes : They are of the size of
when they have to squeeze through capillaries RBC and are round in shape having a
that often have lumens slightly smaller than the very large nucleus that almost fills the
diameter of the red cell. Red cells rarely cause whole of the cell. They produce antibodies
blockages because they have a flexible shape and that provide immunity against specific
a smooth membrane. diseases.
(b) Granular Leucocytes (Granulocytes) :
Granulocytes have granular cytoplasm. All
the granulocytes are produced in the red
bone marrow. Depending upon the chemical
nature of their cytoplasm they are classified
into three types.
(i) Acidophils (Losinophils) : Their cytoplasm
Mammalian blood cells are biconcave discs field with is alkaline in nature. An acidophil has a
Hemoglobin
oilobea nucleus.
(Red blood cells are made in the bone marrow
(ii) Basophils : Their cytoplasm is acidic,
of the vertebrate, ribs and pelvis by specialised
hence, take basic stains. Their nucleus is
stem cells. The turnover of red cells is very rapid:
3-many lobed.
we make about 20 million red cells per second.
(iii) Neutrophils : These form about 70%
Red blood cells circulate for about 100 to 120
of the total leucocytes. Its cytoplasm is
days before they are destroyed in the liver by the
neutral. Its nucleus is many lobed. They
phagocytes called Kupffer cells, and also in the
are phagocytic.
spleen.)
Functions of Leucocytes :
9.3 WBC’s or Leucocytes (White Blood Corpuscles) Defence of the body against diseases and invaders
is the most essential function of leucocytes. They
The leucocytes in general are amoeboid (i.e., perform various functions such as
without any definite shape) nucleated corpuscles. (i) Phagocytosis
They are known as phagocytes- (engulf the foreign (ii) Formation of antibodies and antitoxins
and worn out structures) Scavengers – (engulf the (iii) Immunity
worn out tissues of the body) Soldiers of the body (iv) Metamorphosis
(accumulate at the site of injury and fight with
the invading microorganisms, that may cause 9.4 Blood Platelets (Thrombocytes)
infection.
They are the smallest corpuscles of all the three
The leucocytes vary from 5000-9000/mm3 of
types in regard to their size. They are denucleated.
human blood. They are produced either in the
They are also produced in the red bone marrow
bone marrow or in lymphoid tissues such as
from some giant cells called megakaryocytes.
lymph nodes, spleen, etc. Extraordinary increase
Its lifespan is about 3-5 days and are mainly
in the number of leucocytes is called leukemia and
destroyed in the spleen.
decrease in their number is called leucopenia.
Functions of Platelets :
Types of Leucocytes :
The blood platelets are responsible for the clotting
Based upon the structure, the leucocytes are
of blood at injuries.
classified into two types which are further
CH 7 : THE CIRCULATORY SYSTEM

16.1 Rh Factor in Pregnancy 18. LYMPHATIC SYSTEM

Rh factor is very important as it is inheritable. Lymph (a colourless fluid) and its associated
If an Rh negative woman marries an Rh positive parts constitute lymphatic system. It consists of
man and conceives an Rh positive foetus, the (A) Lymph (B) Lymph capillaries (C) Lymph
first baby may be safe, but following Rh-positive vessels (D) Lymph nodes.
foetuses will die in the womb or soon after birth.
It is because of the fact that Rh-positive foetus 18.1 Lymph
induces the formation of anti-Rh agglutinin in Lymph is a colourless or straw coloured fluid
the Rh- negative blood of mother. During first connective tissue. It is actually a part of tissue
pregnancy, the formation of anti-Rh agglutinin fluid which in turn is filtered out plasma through
is very slow and does not affect the RBCs of the walls of capillaries. So the composition of
foetus. But in the succeeding Rh-positive foetus, lymph is like that of blood plasma minus plasma
the result will be disastrous, as already present proteins which cannot pass through the walls
anti-Rh antibodies in mother’s blood will pass to of capillaries. Source of lymph is blood. Lymph
the foetus through placenta causing agglutination acts as a middle man for the exchange of various
of RBCs of foetus. It may lead to the death of materials between the blood and body tissues.
foetus or newborn baby. This disease is called
erythroblastosis foetalis. Table : Differences between blood and lymph
Blood Lymph
17. PORTAL SYSTEM
1. It is red in 1. It is colourless
(i) A vein which collects blood from one organ by
colour. or straw yellow
one set of capillaries and distributes blood to
coloured.
some other organ by another set of capillaries
instead of sending it to the heart is called a 2. Erythrocytes are 2. Erythrocytes are
portal vein. present. absent.
(ii) A portal vein together with the capillaries by 3. Hemoglobin is 3. Hemoglobin is
which it supplies blood to a specific organ present. absent.
forms a portal system.
4. It contains many 4. Plasma proteins
(iii) A portal system is named after the organ to
plasma proteins. are absent or very
which it carries blood.
low concentration.
(iv) The vertebrates have 2 or 3 portal systems :
hepatic, renal and hypophyseal. 5. Calcium and 5. Low concentration
(v) Hepatic Portal System : It is present in all phosphorus of calcium and
vertebrates, including man. It carries the concentration is phosphorus.
venous blood from the alimentary canal, very high.
pancreas and spleen to the liver, hence its 6. It flows in blood 6. It flows in lymph
name. vessels. vessels and also
(vi) Significance. bathes various
(a) It brings the digestion products, such body tissues.
as glucose and amino acids, from the
alimentary canal to the liver. The liver 7. It helps in the 7. It acts as a
retains the excess sugar and converts transportation middleman for
it into glycogen, which is stored for of various the exchange of
future use. The liver also deaminates the materials. materials between
unwanted amino acids, releasing only blood and body
those that are necessary for the body. tissues.
(b) The liver converts the harmful ammonia
resulting from deamination into urea for 18.2 Lymph Capillaries
removal by the kidneys. Interwoven with the blood capillaries are present
(c) Liver synthesises certain useful substances lymph capillaries which are blind at one end.
and releases them into the blood for use in They have very thin walls. Lymph flows into
the body tissues. These include heparin, lymph capillaries.
fibrinogen, prothrombin and vitamin A.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 213

discovery he was awarded Nobel Prize in 1931. operations to restore the normal vital activities
Landsteiner recognized two types of antigens of the body. A person who donates blood is called
or agglutinogens, i.e., A and B present on the the donor and the person who receives it, is called
plasma membrane of RBCs, hence, also known as the recipient.
corpuscle factors and two types of antibodies or In blood transfusion, the corpuscle factor or
agglutinins i.e., a and b in the plasma, hence, also antigen of the donor should be compatible with
called plasma factors. the plasma factor or antibody of the recipient,
The red blood corpuscles of an individual may otherwise the corpuscles of blood donated become
possess either antigen A or antigen B or both the agglutinated and block the blood vessels and may
antigens or none of them. It is this distribution of prove fatal. The plasma factor of the donor is not
antigens which determines the type of antibodies significant during transfusion as it gets diluted
in the blood as all types of antigens and antibodies when mixed with the plasma of recipient and is
cannot coexist or are not compatible. Antigen A not able to cause agglutination of RBCs of the
is not compatible with antibody a (or Anti-A) recipient. According to this principle, a person
but compatible with antibody-b. Similarly, can receive or donate blood to the other blood
antigen B is incompatible with antibody-b (or groups as given in the table above.
Anti-B) but compatible with antibody a. Thus,
15.1 Universal Donor and Universal Recipients
A and b can exist together, and so can B and a.
The antigens A and B can occur together if their People belonging to blood group O have no
antagonistic plasma factors a and b are lacking. antigen or corpuscle factor in their RBCs. Their
Similarly, antibodies or agglutinins a and b can blood can be administered to any other person,
exist together if their antagonistic antigens A and because neither of the antibodies a and b will
B are absent. agglutinate these cells, hence, they are called
Depending upon the distribution of antigens universal donors. On the other hand, people
and antibodies in the blood, Landsteiner (1900) belonging to blood group AB have both the
classified the blood into three groups and the antigens in their RBCs, but no antibodies in their
fourth blood group was reported by Decastello plasma. So these persons can receive blood from
and Sturli two years later. The four types of blood persons of any blood group, and are, therefore,
groups are named according to the type or types called universal recipients.
of antigens present and are A, B, AB and O. The
antigens and antibodies present in these blood 16. RH FACTOR
groups are given in the table below. Landsteiner and Weiner (1940) discovered the
Table : Various blood groups, their composition presence of another factor in the red blood
and transfusion ability. corpuscles of Rhesus monkey and some humans
which they named as Rh factor. This Rh factor
Blood Antigen Antibody Can Can receive is found in 85% of white population and 93% of
group present present donate blood from
Indian population.
blood
to
A person is said to be Rh positive if its RBCs
contain Rh antigen and Rh negative if he has no
A A B A and A and O Rh antigen on his RBCs. Normally, the blood
AB
of the Rh negative person does not carry any
B B A B and B and O antibody that can react with this antigen. But
AB such antibodies are produced if Rh negative blood
AB A and B None AB All comes across Rh positive blood. In such cases
O None A and B All O the transfused Rh positive blood acts as foreign
bodies to the Rh negative person and his body
proceeds to produce antibodies called anti-Rh
15. BLOOD TRANSFUSION
to destroy the foreign bodies i.e., transfused Rh
In cases of severe blood loss due to some accident positive red blood corpuscles. First transfusion is
or various diseases also and in serious forms of not going to be serious but repeated transfusions
anaemia caused by other reasons, the transfusion may result in severe reaction and ultimately lead
of blood is the only method to save life. It is to the death of Rh negative person.
also necessary during prolonged and serious
CH 7 : THE CIRCULATORY SYSTEM

to the lungs and through the aorta to the rest 9. COMPOSITION OF BLOOD
of the body. This takes 0.3 seconds.
3. Atrial diastole : The atria relax, although the 9.1 Plasma
ventricles are still contracted. Blood enters Plasma is the fluid part of blood. The exact
the atria from the large veins coming from composition of the plasma varies greatly. For
the body. This takes about 0.7 seconds. instance, in the hepatic portal vein, which leads
4. Ventricular diastole : The ventricles relax, from the intestines to the liver, the plasma is
and become ready to fill with blood from much richer in dissolved foods such as sugars,
the atria as the next cycle begins. This takes vitamins and amino acids than the plasma in a
about 0.5 seconds. Given an average heart vein in another part of the body.
rate of 75 beats per minute, each cycle takes The main constituents of plasma
0.8 seconds.
Components Function
8.1 Control of the Cardiac Cycle
Proteins Albumin Osmotic balance
Heartbeat must be carefully controlled so that Antibodies Immunity
each chamber contracts only when full of blood. Fibrinogen Blood clotting
To achieve this, the events of the cardiac cycle are Salts Sodium, potassium, Osmotic balance,
carefully coordinated. chloride bicarbonate conduction of
(hydrogencarbonate) nerve impulses
calcium carriage of O2,
blood clotting
Products glucose, amino Nourishment of
of acids, fatty acids, cells
digestion glycerol, vitamins.

Hormones Protein, e.g., insulin Communication

; lipid (steroids), e.g.
testosterone
Heat Distributed around
body to maintain
constant body
temperature
A single heartbeat starts with an electrical signal
Oxygen Vital in aerobic cell None : they
from a region of specialized tissue called the sino-
Waste respiration must be removed
atrial node (SAN), on the wall of the right atrium. products Urea, CO2 by excretion.
This is the ‘pacemaker’, or heartbeat regulator.
The electrical signal spreads out over the walls of
9.2 Red Blood Cells
the atria, causing them to contract.
From there, the signal does not pass directly to Mammalian red blood cells have nucleus. They
the ventricles. If it did, the ventricles would begin contain Hemoglobin, enzymes and chemicals that
to contract before they had filled with blood. allow them to function effectively. Red blood cells
Instead, the impulse is delayed slightly. A second have one function: they carry the respiratory
node, the atrioventricular node (AVN) picks up gases. The Hemoglobin (Hb) they contain, picks
the signal and channels it down the middle of up oxygen in the lungs and swaps it for carbon
the ventricular septum through a collection of dioxide in the respiring tissues.
specialised cardiac muscle fibres called the bundle Having the Hb inside red blood cells rather than
of His. From here the signal spreads throughout in solution in the plasma gives several advantages.
the wall of the ventricles, through the Purkinje 1. A much greater volume of Hb can be carried
fibres, and the ventricles contract after they have in cells that could be dissolved in plasma.
filled with blood. 2. Hb can be kept in a favourable chemical
environment to allow faster loading and
unloading of respiratory gases.
3. Hb molecules of a particular age are kept
together and can be replaced easily when old.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 215

18.3 Lymph Vessels

MULTIPLE CHOICE QUESTION
Lymph capillaries join to form lymph vessels.
Lymph vessels resemble the veins in structure but
have thinner walls and more valves. The smaller 1. During ventricular systole, the atrioventricular
lymph vessels join to form larger vessels, which in valves (P) .................. and semilunar valves (Q)
turn unite to form two main lymphatic vessels or ..................
trunks called thoracic duct and right lymphatic (a) P — close, Q — Open
duct. The thoracic duct finally opens into left (b) P — close, Q — Close
subclavian vein and the right thoracic duct opens (c) P — open, Q — Close
into right subclavian vein. (d) P — open, Q — Open
Ans : SQP 2025
18.4 Lymph Nodes
Thus (a) is correct option.
Throughout the course of lymph vessels at
intervals are present bead like swellings called 2. Pulse wave is mainly caused by the :
lymph nodes. They are masses of reticular (a) Systole of atria
connective tissue wrapped in a capsule of fibrous (b) Diastole of atria.
tissue. They contain lymphocytes, plasma cells (c) Systole of the left ventricle
and fixed macrophages. The lymph is filtered (d) Systole of the right ventricle.
through the lymph nodes. Macrophages engulf
micro-organisms and foreign particles from the Ans : MAIN 2013

lymph. The lymph nodes also add lymphocytes The pulse is felt over the wrist in the superior
and antibodies to the lymph from where these are artery due to the forceful pumping of blood into
carried to the blood. the arteries during ventricular systole.
Lymph nodes are abundant in the regions of neck, For each left ventricular contraction or systole,
armpits and groins. Tonsils and adenoids are the blood is forced towards arteries to provide
masses of lymphatic tissues. Thymus and spleen systemic circulation of oxygenated blood and
are important lymphatic organs in the body of then released towards the tissues during diastole.
vertebrates. Thus (c) is correct option.

18.5 Functions of Lymph 3. The mineral ion needed for the formation of blood
The lymph performs many functions such as : clot is
(i) It acts as a ‘middleman’ and helps in the (a) Potassium (b) Sodium
exchange of various materials between blood (c) Calcium (d) Iron
and body tissues. Ans : COMP 2016
(ii) It carries lymphocytes and antibodies from
The mineral ion needed for the formation of a
lymph nodes to the blood.
blood clots is calcium.
(iii) It transports fats (fatty acids and glycerol)
Thus (c) is correct option.
from the intestine to the blood.
(iv) It destroys microorganisms and foreign 4. The mineral element in hemoglobin :
particles in the lymph nodes. (a) Manganese (b) Iron
(v) It drains excess of tissue fluid from intercellular (c) Sodium (d) Calcium
spaces back into the blood.
(vi) Spleen as a lymphatic organ acts as ‘blood Ans : SQP 2021

bank’ and ‘graveyard’ or RBCs. Iron is a mineral found in every cell of the body.
(vii) It carries the plasma proteins synthesized in Iron is considered an essential mineral because it
the liver cells and hormones from endocrine is needed to make hemoglobin, a part of blood
glands to the blood. cells.
Thus (b) is correct option.

5. Pericardium covers the :

(a) Heart (b) Brain
(c) Spinal cord (d) Eyeball
Ans : COMP 2021
CH 7 : THE CIRCULATORY SYSTEM

10. BLOOD CLOTTING OR COAGULATION the site of injury, in which RBCs get entangled
Clotting or coagulation of blood is of great and form a clot. A clot is formed at the injury
biological value for the survival of animals. When within 2-6 minutes. Soon after its formation, the
a vessel is injured, a blood clot forms at the site clot starts contracting and a pale yellow fluid-the
of injury. This acts as a plug, thereby sealing serum starts oozing out.
the ruptured blood vessel. It stops bleeding and Why does blood not clot within the blood vessels?
prevents loss of vital body fluid. A decrease in The blood contains an anticoagulant called
capacity of the blood to clot leads to profuse and heparin (antithrombin) that does not allow the
fatal haemorrhages even if the injury is slight. formation of prothrombinase within the blood
vessels.
10.1 Mechanism of Blood Clotting
In certain diseases blood clots are formed
The blood clotting involves a series of chemical within the blood vessels. These clots are called
reactions taking place in a rapid sequence. There thrombi and their formation is called thrombosis.
are following three steps : Thrombosis in coronary artery (artery that
First step : At the site of injury a phospholipid supplies blood to heart muscles) leads to heart
called platelet factor-3 (= platelet thromboplastin) attack. When a thrombus is transported by the
is released by the disintegration of blood platelets. bloodstream it is called embolus which causes
Another lipoprotein factor called thromboplastin embolism when lodged in a vessel and cuts off
is also released by the injured tissue. The two circulation.
factors so released combine with calcium ions and
some plasma proteins to form an enzyme called 10.2 Role of Vitamin K in Blood Clotting
thrombokinase or prothrombinase.
Vitamin K is essential for the synthesis of
Second step : Thrombokinase enzyme converts
prothrombin and fibrinogen proteins by the liver
inactive plasma protein prothrombin into active
cells. These proteins are essential for the clotting
form called thrombin. This activity needs Ca++
of blood.
and some plasma factors.
11. ANTICOAGULANTS
The substances which prevent clotting of blood
are called anticoagulants.
Sodium oxalate, Sodium citrate are used as
anticoagulants. Heparin in our blood and hirudin
found in the salivary glands of leeches are also
anticoagulants.

12. BLOOD BLISTERS

Blood blisters are formed without the blood
coming in contact with air. These may be formed
due to injuries like sharp pinch when the skin
does not break.

13. DEFIBRINATED BLOOD

Blood from which fibrin has been removed is
called defibrinated blood. It consists of serum and
formed elements and does not clot.

14. ABO, BLOOD GROUPS

Mechanism of blood clotting
Third step : Soluble plasma protein fibrinogen is Carl Landsteiner (1900) was the first, who
converted into insoluble protein called fibrin with discovered that the blood of individuals differed
the help of thrombin. By the polymerization the chemically. The clumping of red blood corpuscles
fibrin protein forms long fibrin threads. These (agglutination) occurred when the blood of
fibrin threads form a very fine network (mesh) at different chemical types was mixed with. For this
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 217
Ans : MAIN 2023
tissue capillaries, the deoxygenated blood returns
A mechanism in which blood circulates twice through a system of veins to the right atrium of
through the heart in one complete cycle is known the heart.
as double circulation. Systemic circulation and Thus (d) is correct option.
pulmonary circulation are two pathways in which
the blood flows in double circulation. Double 18. Bicuspid and tricuspid valves are closed during
circulation is present in birds and mammals. (a) Ventricular diastole
Thus (d) is correct option. (b) Ventricular systole
(c) Atrial systole
14. In man, the portal vein carries blood from the (d) Late joint diastole
intestine to the Ans : SQP 2017
(a) Liver (b) Kidney
(b) Heart (d) Both (a) and (b) Semilunar valves are open during ventricular
systole, forcing the blood to flow into the
Ans : SQP 2004
pulmonary artery. Bicuspid and tricuspid valves
In humans, the portal vein carries nutrient-rich get closed at the beginning of ventricular systole.
blood from the intestine and other parts of the Thus (b) is correct option.
digestive system to the liver. The liver processes
the nutrients and detoxifies harmful substances 19. The chief function of lymph nodes in mammals
before the blood is circulated to the rest of the is to
body. Thus (a) is correct option. (a) Produce hormones (b) Produce WBCs
(c) Sestroy old RBCs (d) Destroy pathogen
15. Normal blood pressure in human is
(a) 80/120 mm Hg (b) 80/110 mm Hg Ans : MAIN 2015

(c) 100/80 mm Hg (d) 120/80 mm Hg The chief function of lymph nodes in the
Ans : COMP 2019 mammalian body is to collect and destroy
pathogens.
Normal blood pressure for most adults is defined
Thus (b) is correct option.
as a systolic pressure of less than 120 and a
diastolic pressure of less than 80. 20. Which one of the following blood vessels carries
Thus (d) is correct option. only deoxygenated blood?
(a) Pulmonary artery
16. Which of the following cells do not exhibit
(b) Pulmonary vein
phagocytic activity?
(c) Aorta
(a) Monocytes (b) Neutrophil
(d) Capillaries
(c) Macrophage (d) Basophil
Ans : MAIN 2021 Ans : SQP 2016

Phagocytes have the ability to phagocytose or Capillaries are thin-walled vessels composed of
kill foreign cells and particles like pathogens a single endothelial layer. Because of the thin
by ingesting them. Many blood cells have this walls of the capillary, the exchange of nutrients
function, including monocytes, neutrophils and and metabolites occurs primarily via diffusion.
macrophages. Basophils do not have phagocytic The arteriolar lumen regulates the flow of blood
activity. through the capillaries.
Thus (d) is correct option. Thus (a) is correct option.

17. Systemic circulation is 21. Find the incorrect statement from the following
(a) Left ventricle Deoxygenated Tissues
Oxygenated
Right ventricle (a) Because of their small size, capillaries contain
blood blood

(b) Right ventricle Oxygenated Tissues

Deoxygenated
Right auricle blood that moves more quickly than in other
blood blood

(c) Left ventricle Deoxygenated Tissues

Oxygenated
Right auricle part of circulation.
blood blood

(d) Left ventricle Oxygenated Tissues

Deoxygenated
Right auricle (b) Veins are larger in diameter than arteries.
blood blood
(c) Wall of arteries are elastic, enabling them to
Ans : MAIN 2000
stretch and shrink during changes in blood
Systemic circulation carries oxygenated blood pressure.
from the left ventricle, through the arteries, to (d) Veins contain maximum amount of blood.
the capillaries in the tissues of the body. From the
CH 7 : THE CIRCULATORY SYSTEM

61. During a medical discussion, a doctor explains Ans : COMP 2017

that a specific blood vessel is responsible for Renal vein contains the least amount of urea.
supplying oxygenated blood to the kidneys for Thus (d) is correct option.
filtration. This blood vessel is the:
(a) Renal artery (b) Renal vein 65. During a heart examination, the doctor explains
(c) Dorsal aorta (d) Hepatic vein that a specific valve between the right atrium and
right ventricle ensures blood flows in one direction
Ans : MAIN 2018
and prevents backflow. This valve is called:
The renal arteries are large blood vessels that (a) Mitral valve (b) Bicuspid valve
carry blood from your heart to your kidneys. (c) Semilunar valve (d) Tricuspid valve
Renal is another word for kidney. You have two Ans : SQP 2014
renal arteries. The right renal artery supplies
The valve that is present between the left atrium
blood to the right kidney, while the left artery
and left ventricle of the heart is called the bicuspid
sends blood to the left kidney.
or mitral valve.
Thus (a) is correct option.
It consists of two cusps or flaps that prevent
62. During a discussion on blood vessels, a professor the backflow of oxygenated blood from the left
mentions that one type of blood vessel has walls ventricle to the left atrium.
made of only a thin layer of endothelium to allow Thus (d) is correct option.
easy exchange of substances. Which one of the
66. During a blood transfusion, the doctor explains
following consists of a thin layer of endothelium
that one specific blood group can be donated
only?
to people of any blood type because it does not
(a) Arterioles (b) Venules
contain any antigens that can cause a reaction.
(c) Valves (d) Capillaries
Which is the universal donor blood group?
Ans : COMP 2009 (a) A (b) O
Capillaries are thin-walled vessels composed of (c) B (d) AB
a single endothelial layer. Because of the thin Ans : MAIN 2002
walls of the capillary, the exchange of nutrients
O negative donors are often called 'universal
and metabolites occurs primarily via diffusion.
donors' because anyone can receive the red blood
The arteriolar lumen regulates the flow of blood
cells from their donations.
through the capillaries.
Thus (d) is correct option.

63. A doctor explains that white blood cells defend

the body by surrounding and digesting harmful
bacteria. This process is called:
(a) Phagocytosis (b) Diapedesis
(c) Active transport (d) Passive transport
Ans : COMP 2014

White blood cells like neutrophils. monocytes,

macrophages, mast cells, dendritic cells etc, Thus (b) is correct option.
defend the body by engulfing pathogens. This
process is called phagocytosis. 67. A doctor is examining a patient’s pulse during
Thus (a) is correct option. a routine check-up. The doctor notices the pulse
rate is slightly elevated and explains that this is
64. During a study of blood composition, a doctor due to the heart’s pumping action, specifically
explains that a particular blood vessel carries the during the contraction phase. Based on this
least amount of urea after it has been filtered by observation, the pulse wave is mainly caused by:
the kidneys. Which of the following blood vessels (a) Systole of the left ventricle
in humans carries the least concentration of urea? (b) Systole of atria.
(a) Hepatic vein (b) Hepatic artery (c) Diastole of atria.
(c) Renal artery (d) Renal vein (d) Systole of the right ventricle.
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pressure is the pressure exerted on the walls of 31. Double circulation means
the arteries when the heart contracts and pumps (a) Every organ has an artery and a vein.
blood. (b) Blood flows twice through the heart.
Thus (d) is correct option. (c) Oxygenated and deoxygenated blood is
separated.
28. The opening of right atrium into right ventricle of (d) Both (a) and (b)
human heart is guarded by
(a) Mitral valve Ans : MAIN 2023

(b) Tricuspid valve Double circulation refers to the process where

(c) Pulmonary semilunar valves blood passes twice through the heart in one
(d) Bicuspid valve complete cycle. First, it goes from the heart to the
Ans : COMP 2005
lungs to get oxygen (pulmonary circulation), and
then it returns to the heart and is pumped out to
The opening of the right atrium into the right the rest of the body (systemic circulation). This
ventricle is guarded by the tricuspid valve. This ensures that oxygenated and deoxygenated blood
valve prevents the backflow of blood from the are kept separate for efficient oxygen supply to
right ventricle into the right atrium when the the body.
ventricle contracts. Thus (d) is correct option.
Thus (b) is correct option.
32. Bicuspid valve is present between
29. The left ventricle possesses a thicker wall than (a) Right atrium and right ventricle.
right ventricle because (b) Left atrium and right atrium.
(a) it receives deoxygenated blood from left (c) Right ventricle and left ventricle.
atrium.
(d) Left atrium and left ventricle.
(b) it receives oxygenated blood from left atrium.
(c) it pumps oxygenated blood out of the heart. Ans : SQP 2018
(d) it pumps deoxygenated blood out of the The bicuspid valve, also known as the mitral
heart. valve, is located between the left atrium and the
Ans : MAIN 2013 left ventricle. It ensures that blood flows in one
direction from the left atrium to the left ventricle
The left ventricle possesses a thicker wall than
and prevents the backflow of blood when the left
the right ventricle because it pumps oxygenated
ventricle contracts.
blood out of the heart to the entire body through
Thus (d) is correct option.
the aorta. This requires a greater force compared
to the right ventricle, which only pumps blood to 33. Pulse wave is mainly caused by the
the lungs. The thicker muscular wall of the left (a) Systole of atria
ventricle enables it to generate the higher pressure (b) Diastole of atria
needed to circulate blood throughout the body. (c) Systole of the right ventricle
Thus (c) is correct option. (d) Systole of the left ventricle
30. When a doctor is recording your pulse, he is Ans : COMP 2016
pressing on your wrist exactly on a The pulse wave is mainly caused by the systole of
(a) Artery (b) Capillary the left ventricle. When the left ventricle contracts
(c) Vein (d) Arteriole during systole, it forces blood into the aorta,
Ans : COMP 2020 creating a pressure wave that travels through the
arteries, which is felt as a pulse.
When a doctor is recording your pulse, they are
Thus (d) is correct option.
pressing on an artery. The pulse is the rhythmic
expansion and contraction of the arteries as blood 34. The duration of a cardiac cycle is
is pumped through them by the heart. The most (a) 0.6 second
common place to check the pulse is the radial (b) 0.7 second
artery on the wrist. (c) 0.9 second
Thus (a) is correct option. (d) 0.8 second
Ans : MAIN 2002
CH 7 : THE CIRCULATORY SYSTEM
Ans : MAIN 2001
Thromboplastin is a substance that, when
Capillaries are small in size, but blood moves introduced into the bloodstream, triggers the
more slowly through them compared to other coagulation process at the site of introduction.
parts of circulation. This slower movement allows Thromboplastin initiates the conversion of
for the exchange of oxygen, nutrients, and waste prothrombin into thrombin, which in turn
between the blood and tissues. The rest of the converts fibrinogen into fibrin, leading to blood
statements are correct: veins are larger in diameter clot formation.
than arteries, arterial walls are elastic, and veins Thus (c) is correct option.
contain the maximum amount of blood.
Thus (a) is incorrect option. 25. Non-granular WBCs are :
(a) Lymphocytes and basophils
22. The first heart sound is produced when
(b) Eosinophils and basophils
(a) Bicuspid and tricuspid valves close quickly
(c) Lymphocytes and monocytes
(b) Diastole begins
(d) Eosinophils and monocytes
(c) Semilunar valves close quickly
(d) Inter-ventricular pressure increases Ans : COMP 2018

Ans : SQP 2006

Non-granular white blood cells (WBCs), also
known as agranulocytes, are lymphocytes and
First heart sound is produced by the closing monocytes. These cells lack the granules present
of the atrioventricular valves . The first heart in other types of WBCs such as neutrophils,
sound, or S1, forms the "lub" of "lub-dub" and is eosinophils, and basophils. Lymphocytes play a
composed of components M1 (mitral valve closure) key role in the immune response, and monocytes
and T1 (tricuspid valve closure). Normally M1 are involved in phagocytosis.
precedes T1 slightly. It is caused by the closure Thus (c) is correct option.
of the atrioventricular valves, i.e. tricuspid and
mitral (bicuspid), at the beginning of ventricular 26. SA node is called the pacemaker of the heart
contraction, or systole. So, the correct option is because
C.( Bicuspid and tricuspid close quickly ) (a) it generates the cardiac impulse
Thus (a) is correct option. (b) it conducts the impulse from AV node
(c) it is present in the right atrium
23. Rate of heart beat is controlled by (d) it is made up of specialised muscle fibres
(a) Cranial nerves
(b) SA node Ans : SQP 2001

(c) Sympathetic nerves The SA node (sinoatrial node) is called the

(d) Spinal nerves pacemaker of the heart because it generates the
Ans : COMP 2022
cardiac impulse that initiates each heartbeat. The
SA node creates electrical signals that spread
Heart rate is controlled by the two branches of throughout the heart, causing the atria and
the autonomic (involuntary) nervous system. then the ventricles to contract in a coordinated
The sympathetic nervous system (SNS) and the manner. This maintains the heart's rhythm.
parasympathetic nervous system (PNS). The Thus (a) is correct option.
sympathetic nervous system (SNS) releases the
hormones (catecholamines - epinephrine and 27. Systolic pressure in normal adult human is
norepinephrine) to accelerate the heart rate. (a) 80 mm
Thus (b) is correct option. 120
b) 80 mm Hg
24. Which of the following substances if introduced
into bloodstream, would cause coagulation at the 150
(c) 120 mm Hg
site of introduction?
(a) Fibrinogen (d) 120 mm Hg
(b) Prothrombin
Ans : MAIN 2019
(c) Thromboplastin
(d) Heparin The normal systolic pressure in a healthy adult
human is approximately 120 mm Hg. Systolic
Ans : SQP 2011
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 221
Ans : SQP 2009 Ans : COMP 2023

Heart sounds are produced due to the closure of The lungs are the nearest organ to which the
the tricuspid and bicuspid (mitral) valves. The heart supplies oxygenated blood. Although
first heart sound ("lub") is heard when these the heart supplies blood to itself through the
atrioventricular valves close during the start of coronary arteries, the primary circulation of
ventricular contraction (systole). This sound oxygenated blood goes to the lungs first through
results from the vibrations caused by the closing the pulmonary circulation before reaching other
of these valves and the sudden halt of blood flow. organs.
Thus (b) is correct option. Thus (b) is correct option.

42. Left atrium receives oxygenated blood through 46. The opening of right auricle into the right ventricle
(a) Coronary artery (b) Pulmonary vein is guarded by
(c) Pulmonary artery (d) Aorta (a) Bicuspid valve
(b) Aortic semi-lumar valve
Ans : MAIN 2013
(c) Tricuspid valve
The left atrium receives oxygenated blood from (d) Pulmonary semi-lunar valve
the lungs through the pulmonary veins. These
veins carry oxygen-rich blood from the lungs to Ans : SQP 2017

the left atrium, which then pumps it into the left The opening between the right auricle (atrium)
ventricle to be distributed throughout the body. and the right ventricle is guarded by the tricuspid
Thus (b) is correct option. valve. This valve ensures one-way flow of blood
from the right atrium to the right ventricle and
43. Artery is a blood vessel which carries blood prevents backflow during ventricular contraction.
(a) Towards the heart Thus (c) is correct option.
(b) Away from the heart
(c) Has deoxygenated blood without exception 47. Human blood consists of
(d) None of these (a) Plasma
(b) Fluid matrix
Ans : COMP 2010
(c) Formed elements
An artery is a blood vessel that primarily carries (d) All of these
blood away from the heart. Most arteries carry
Ans : MAIN 2013
oxygenated blood, except for the pulmonary
artery, which carries deoxygenated blood to the Human blood consists of three primary
lungs for oxygenation. components: plasma, fluid matrix, and formed
Thus (b) is correct option. elements. Plasma is the liquid portion of blood,
making up about 55% of its volume, and serves as
44. Leucocytes are colourless due to a medium to transport nutrients, hormones, and
(a) Lack of water waste products throughout the body. The fluid
(b) lack of Hemoglobin matrix refers to the plasma itself, which helps in
(c) Presence of lipid maintaining the circulation of blood. The formed
(d) Presence of Hemoglobin elements, which make up the remaining 45%,
Ans : SQP 2018
include red blood cells (RBCs), white blood cells
(WBCs), and platelets. These formed elements
Leucocytes (white blood cells) are colourless play crucial roles in oxygen transport, immune
because they lack Hemoglobin, the pigment defense, and blood clotting, respectively.
responsible for the red color in red blood cells. Thus (d) is correct option.
Leucocytes are involved in the immune response
and do not require Hemoglobin for oxygen 48. Which of the following blood vessels has a thick
transport. middle layer of smooth muscles and elastic fibres?
Thus (b) is correct option. (a) Arterioles
(b) Arteries
45. The nearest organ to which the heart supplies (c) Veins
oxygenated blood is (d) Bone
(a) Stomach (b) Lung
(c) Intestine (d) Heart itself Ans : COMP 2008
CH 7 : THE CIRCULATORY SYSTEM

The duration of a normal cardiac cycle in a 38. Blood is a

healthy adult is approximately 0.8 seconds. This (a) Liquid connective tissue
includes both systole (contraction) and diastole (b) Mobile connective tissue
(relaxation) of the heart, which allows for one (c) Both (a) and (b)
complete heartbeat. (d) Semi-solid connective tissue
Thus (d) is correct option.
Ans : COMP 2015

35. Hepatic portal system starts from Blood is considered both a liquid connective
(a) Kidney to liver tissue and a mobile connective tissue. It is
(b) Liver to heart classified as connective tissue because it consists
(c) Digestive system to liver of cells suspended in a liquid matrix (plasma)
(d) Liver to kidney and performs vital functions like transport of
nutrients, gases, and waste products, while also
Ans : SQP 2018
circulating throughout the body.
The hepatic portal system is a network of veins Thus (c) is correct option.
that carries blood from the digestive system to
the liver. This system allows the liver to process 39. Which of the following chambers of heart first
nutrients, detoxify harmful substances, and receives blood from the systemic circulation?
regulate blood sugar before the blood enters (a) Left ventricle
general circulation. (b) Right ventricle
Thus (c) is correct option. (c) Left auricle
(d) Right auricle
36. The instrument by which Blood Pressure is
Ans : COMP 2023
determined
(a) Ultrasound The right auricle (or right atrium) is the first
(b) BP meter chamber of the heart that receives deoxygenated
(c) Sphygmomanometer blood from the systemic circulation through the
(d) Stethoscope superior and inferior vena cava. From there, the
blood is pumped into the right ventricle before
Ans : MAIN 2000 being sent to the lungs for oxygenation.
The instrument used to determine blood pressure Thus (d) is correct option.
is called a sphygmomanometer. It typically
40. The valve present between the right atrium and
consists of an inflatable cuff to restrict blood flow,
the right ventricle is the
a measuring unit (a mercury column or gauge),
(a) Bicuspid valve
and sometimes a stethoscope to listen to the
(b) Tricuspid valve
blood flow.
(c) Semi-lunar valve
Thus (c) is correct option.
(d) Mitral valve
37. When two atria contract simultaneously and Ans : MAIN 2004
result in the blood pumping into ventricles, this
The valve present between the right atrium and
is called
the right ventricle is the tricuspid valve. This valve
(a) Arterial diastole
ensures that blood flows from the right atrium to
(b) Ventricular systole
the right ventricle and prevents backflow when
(c) Ventricular diastole
the ventricle contracts.
(d) Arterial systole
Thus (b) is correct option.
Ans : SQP 2012
41. Heart sounds are produced due to
When the two atria contract simultaneously to (a) Rushing of blood through valves producing
pump blood into the ventricles, this phase is called turbulence.
atrial systole (or arterial systole). During this (b) Closure of tricuspid and biscupid valves.
phase, the atria contract to push blood into the (c) Closure of atrioventricular and semilunar
ventricles, which are in a relaxed state (diastole). valves.
Thus (d) is correct option. (d) Entry of blood into auricles.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 223
Ans : COMP 2019
(a) Basophils
The left ventricle has the thickest wall because (b) Neutrophils
it needs to pump oxygenated blood with high (c) Lymphocytes
pressure to all parts of the body through the aorta. (d) Eosinophils
This requires stronger contractions compared to Ans : SQP 2021
the other chambers of the heart.
Thus (c) is correct option. Lymphocytes are a type of agranulocyte
responsible for the immune response in the
56. During a heart examination, a doctor explains that body. They play a crucial role in identifying and
a specific node in the heart generates electrical attacking pathogens like bacteria and viruses.
impulses that regulate the heart’s rhythm, acting Lymphocytes include T-cells and B-cells, which
as the natural pacemaker. The pacemaker of the are essential for adaptive immunity, making
heart is: them key players in defending the body against
(a) AV node infections.
(b) SV node Thus (c) is correct option.
(c) SA node 59. During a heart check-up, a doctor explains that
(d) tricuspid valve one of the heart's chambers is responsible for
Ans : MAIN 2021
sending deoxygenated blood to the lungs for
oxygenation. This chamber of the heart is:
The SA node (sinoatrial node) is known as the (a) Right auricle
pacemaker of the heart because it generates the (b) Left ventricle
electrical impulses that initiate each heartbeat. (c) Left auricle
These impulses cause the heart to contract and (d) Right ventricle
regulate the heart's rhythm.
Thus (c) is correct option. Ans : SQP 2004

The right ventricle is the chamber of the heart

57. During a medical discussion, a biology teacher that sends deoxygenated blood to the lungs via
explains that red blood cells must pass through the pulmonary artery for oxygenation. The right
the heart as they move between different parts side of the heart handles deoxygenated blood,
of the body, including the hepatic artery and the while the left side handles oxygenated blood.
aorta. How many times will a red blood corpuscle Thus (d) is correct option.
pass through the heart in its journey from the
hepatic artery to the aorta? 60. During a health lecture, a doctor explains that
(a) Only once lymph nodes play a crucial role in the immune
(b) Two times system by performing a specific function that
(c) Several times helps protect the body from infections. The chief
(d) Four times function of lymph nodes is to
Ans : SQP 2010 (a) Produce WBCs
A red blood corpuscle will pass through the heart (b) Produce hormones
twice in its journey from the hepatic artery to the (c) Destroy pathogens
aorta. This is because it will first pass through the (d) Destroy old RBCs
heart when it goes to the lungs for oxygenation Ans : MAIN 2013
(via the right atrium and right ventricle), and
The chief function of lymph nodes is to destroy
then it will pass through the heart again when it
pathogens. Lymph nodes act as filters for the
returns from the lungs and is pumped out through
lymphatic fluid, trapping bacteria, viruses,
the aorta (via the left atrium and left ventricle).
and other harmful microorganisms. They
Thus (b) is correct option.
contain immune cells, such as lymphocytes
58. A doctor explains that a type of agranulocyte and macrophages, which identify and destroy
is crucial for the body's immune response, as it these pathogens to help protect the body from
produces antibodies and helps fight infections. infections.
This agranulocyte is: Thus (c) is correct option.
CH 7 : THE CIRCULATORY SYSTEM
Ans : MAIN 2017
DIRECTION : Choose the ODD one out from the
Platelets $ Thromboplastin $ Thrombin, following terms given and name the CATEGORY to
$ Fibrinogen $ Fibrin. which the others belong : Example : Nose, Tongue,
Arm, Eye Answer : Odd Term - Arm, Category -
142. Foetus : Amnion : : Heart : _____ Sense organs
Ans : SQP 2017
152. Lumen, muscular tissue, connective tissue,
Foetus : Amnion : : Heart : Pericardium
pericardium
143. Capacity of our body to resist diseases. Ans : SQP 2018

Ans : COMP 2015 Odd term – Pericardium,Category – Parts of

Immunity blood vessels

144. The fluid portion of blood. DIRECTION : Give scientific reasons :

Ans : SQP 2014
153. Give scientific reasons for the Blood flows in
Plasma
arteries in spurts and is under pressure.
145. Coronary artery Ans : MAIN 2016

Ans : MAIN 2011 Blood flows in arteries is jerky and under pressure
It supplies oxygenated blood to the walls of heart. because the blood is being pumped in the arteries
by the rhythmic beating of the heart.
146. WBCs squeeze out through the walls of the
capillaries into the tissues. 154. Give scientific reasons for the Mature erythrocytes
in humans lack nucleus and mitochondria.
Ans : COMP 2012
Ans : COMP 2016
Diapedesis.
Degeneration of nucleus and most of the cell
organelles takes place during maturation of
DIRECTION : State the exact location : mammalian erythrocytes so as to accommodate
more Hemoglobin for the transportation of more
147. Chordae tendinae. oxygen.
Ans : SQP 2016
155. The left ventricle of the heart has a thicker wall
Attach free margins of bicuspid and tricuspid than the right ventricle.
valves with the papillary muscles.
Ans : COMP 2017

148. Pulmonary semilunar value. It has to push the blood to the remotest parts
Ans : MAIN 2018, 2013 of the body such as toes of the feet so the left
ventricle of the heart has thicker wall.
Opening of pulmonary artery.
156. Blood flows in arteries in spurts and is under
149. Mitral valve.
pressure.
Ans : SQP 2011
Ans : SQP 2011
Heart (left atrioventricular aperture of heart).
Arteries have to carry blood to longer distances,
150. Bicuspid valve/Mitral valve. therefore blood flows with jerks and is away under
pressure.
Ans : MAIN 2015, 2011

Between the left auricle and left ventricle. 157. The left ventricle of the heart has a thicker wall
than the right ventricle.
151. Tricuspid valve Ans : MAIN 2008
Ans : COMP 2014
Left ventricle has to pump blood to longer
Between the right atrium and right ventricle. distances with high pressure, so the left ventricle
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 225
Ans : SQP 2013 Ans : COMP 2010

The pulse wave is mainly caused by the systole of Auxin, cytokinin, and gibberellin are plant
the left ventricle hormones. Insulin is a hormone in animals, not
Thus (a) is correct option. plants. Thus (b) is the correct option.

71. A biology teacher asked her students to give two

DIRECTION : Conversation Type Question examples of enzymes involved in digestion.
Raj said : - Amylase and lipase
68. A biology teacher asked her students to give two
Sonu said : - Pepsin and insulin
examples of excretory organs in the human body.
Lata said : - Amylase and pepsin
Raj said : - Kidneys and lungs
Abhay said : - Trypsin and insulin
Sonu said : - Liver and pancreas
Who were correct?
Lata said : - Kidneys and skin
(a) Raj and Lata
Abhay said : - Lungs and large intestine
(b) Raj and Abhay
Who were correct?
(c) Lata and Sonu
(a) Raj and Lata
(d) Sonu and Abhay
(b) Sonu and Abhay
(c) Lata and Abhay Ans : MAIN 2015
(d) Raj and Abhay Amylase, lipase, pepsin, and trypsin are digestive
Ans : MAIN 2002 enzymes. Insulin is a hormone, not an enzyme.
Thus (a) is the correct option.
Kidneys and lungs are correct excretory organs,
as kidneys excrete urine and lungs expel carbon 72. A biology teacher asked her students to give two
dioxide. Skin also excretes salts and urea through examples of carbohydrates.
sweat. Thus (c) is the correct option. Raj said : - Glucose and fructose.
Sonu said : - Glucose and protein.
69. A biology teacher asked her students to give two
Lata said : - Starch and glucose.
examples of connective tissues in the human body.
Abhay said : - Protein and fructose.
Raj said : - Blood and cartilage
Who were correct?
Sonu said : - Bone and muscle
(a) Raj and Lata
Lata said : - Cartilage and tendon
(b) Sonu and Abhay
Abhay said : - Muscle and blood
(c) Lata and Abhay
Who were correct?
(d) Raj and Sonu
(a) Raj and Lata.
(b) Sonu and Lata. Ans : SQP 2000
(c) Raj and Sonu. Glucose, fructose, and starch are carbohydrates.
(d) Abhay and Lata. Proteins are macromolecules made of amino acids,
Ans : SQP 2005 not carbohydrates. Thus (a) is the correct option.
Blood, cartilage, and tendon are connective DIRECTION : Matching Type Question
tissues. Muscles are not classified as connective
tissue but as muscular tissue. Thus (d) is the 73. Priya tried to match the components of the blood
correct option. with their characteristics. She tabulated the pairs
as follows:
70. A biology teacher asked her students to give two
examples of plant hormones. Blood Characteristic
Raj said : - Auxin and cytokinin. Component
Sonu said : - Cytokinin and insulin. P Biconcave shape and no nucleus
Lata said : - Gibberellin and auxin.
Abhay said : - Insulin and gibberellin. Q Involved in clotting of blood
Who were correct? Identify the correct pair of blood components.
(a) Raj and Lata (a) P – White Blood Cells, Q – Red Blood Cells
(b) Sonu and Lata (b) P – Platelets, Q – White Blood Cells
(c) Abhay and Raj (c) P – Red Blood Cells, Q – Platelets
(d) Sonu and Abhay (d) P – Plasma, Q – Platelets
CH 7 : THE CIRCULATORY SYSTEM

Arteries have a thick middle layer composed of 52. SA node is located in

smooth muscles and elastic fibers. This structure (a) Upper lateral wall of left atrium
allows arteries to withstand and regulate the high (b) Upper lateral wall of right atrium
pressure of blood as it is pumped from the heart (c) Lower lateral wall of left atrium
to the rest of the body. The elasticity also helps (d) Lower lateral wall of right atrium
maintain blood flow during diastole (when the
Ans : MAIN 2010
heart relaxes).
Thus (b) is correct option. The SA node (sinoatrial node) is located in the
upper lateral wall of the right atrium. It is the
49. Pulse wave is mainly caused by the natural pacemaker of the heart, responsible for
(a) Systole of the left ventricle generating the electrical impulses that regulate
(b) Systole of atria the heart's rhythm.
(c) Diastole of atria Thus (b) is correct option.
(d) Systole of the right ventricle.
53. Angina Pectoris is due to
Ans : SQP 2005
(a) Defective nutrition
The pulse wave is primarily caused by the systole (b) Defective functioning of mitral valve
of the left ventricle. When the left ventricle (c) Infection by a virus
contracts, it forces blood into the aorta, creating (d) Chest pain due to inadequate supply of
a pressure wave that travels through the arteries, oxygen to the heart muscle
which can be felt as a pulse in areas such as the
Ans : SQP 2014
wrist.
Thus (a) is correct option. Angina Pectoris is a condition characterized by
chest pain due to the inadequate supply of oxygen
50. When the right atrium contracts, blood flows to the heart muscle. This typically happens when
from the right atrium into the the coronary arteries are narrowed or blocked,
(a) Right ventricle reducing the flow of oxygen-rich blood to the
(b) Left atrium heart.
(c) Pulmonary artery Thus (d) is correct option.
(d) Aorta
54. A medical student is studying the flow of blood
Ans : MAIN 2001
through the heart. During their studies, they learn
When the right atrium contracts, blood flows into about the various blood vessels that contribute
the right ventricle through the tricuspid valve. to the heart's chambers. Which blood vessel is
This is part of the process of deoxygenated blood responsible for delivering oxygenated blood into
moving from the body into the heart, eventually the left atrium?
being pumped to the lungs for oxygenation. (a) Superior vena cava
Thus (a) is correct option. (b) Inferior vena cava
120
(c) Pulmonary vein
51. If the blood pressure is measured as 80 mm of (d) Pulmonary artery
Hg, the term 120 refers to
(a) Heartbeat rate Ans : MAIN 2006

(b) Pulse rate Blood is poured into the left atrium through the
(c) Systolic pressure pulmonary veins, which carry oxygenated blood
(d) Diastolic pressure from the lungs to the heart.
Ans : COMP 2000
Thus (c) is correct option.

The 120 in a blood pressure reading (e.g., 120/80 55. In a cardiology lecture, a professor explains that
mm Hg) refers to the systolic pressure, which one chamber of the heart has a thick muscular
is the pressure in the arteries when the heart's wall to pump blood effectively throughout the
left ventricle contracts and pumps blood into the body. Which of the following has the thickest
aorta. wall?
Thus (c) is correct option. (a) Right ventricle (b) Right auricle
(c) Left ventricle (d) Left auricle
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 227

DIRECTION : Give appropriate terms for the Ans : MAIN 2018

following : Diapedesis

84. The respiratory pigment contained in human 93. The relaxation phase of the heart.
blood. Ans : COMP 2018

Ans : MAIN 1996 Diastole

Hemoglobin
94. Blood vessels carrying blood to the right atrium.
85. The blood vessel that supplies oxygenated blood Ans : SQP 2006
to liver.
Vena Cava (superior and inferior)
Ans : SQP 1999
95. The process of engulfing microbes by WBC.
Hepatic artery
Ans : MAIN 2000
86. The process by which leucocytes squeeze out
Phagocytosis
through walls of capillaries.
Ans : COMP 2001 96. The largest artery that carries oxygenated blood
to the organs.
Diapedesis
Ans : COMP 2017
87. The element required for the clotting of blood in
Aorta.
man.
Ans : MAIN 2003
DIRECTION : Name the following :
Calcium
97. The blood vessel which supplies blood to the liver.
88. The blood vessel leaving the left ventricle of the
mammalian heart. Ans : SQP 2018

Ans : SQP 1997 Hepatic artery [Hepatic Portal Vein can also
be the answer because the type of blood is not
Dorsal Aorta
specified].

DIRECTION : Give the Biological / technical term 98. Name the mineral essential for clotting of the
for : blood.
Ans : MAIN 2011
89. The vein which drains the blood from the intestine
Calcium is responsible for clotting of the blood.
to the liver.
Ans : COMP 2016 99. Name the part of plasma from where fibrinogen
is removed.
Hepatic portal vein
Ans : COMP 2011
90. Chemicals found in the blood which act against
Serum.
antigens.
Ans : MAIN 2013 100. The vein that carries oxygenated blood.
Antibodies Ans : MAIN 2015

Pulmonary vein.
91. Cellular components of blood containing
Hemoglobin. 101. The vein which carries blood from the kidney.
Ans : SQP 2017 Ans : SQP 2010

Red blood cells/Red blood corpuscles Renal vein

92. Squeezing out of white blood cells from the 102. A straw coloured fluid connective tissue without
capillaries into the surrounding tissues. RBCs.
CH 7 : THE CIRCULATORY SYSTEM
Ans : COMP 2011
Identify the correct pair of blood components.
Red blood cells are biconcave and lack a nucleus, (a) P – Plasma, Q – Red Blood Cells
while platelets are involved in the clotting process. (b) P – Platelets, Q – White Blood Cells
Thus (c) is the correct option. (c) P – Plasma, Q – Platelets
(d) P – White Blood Cells, Q – Red Blood Cells
74. Priya tried to match the functions of different
types of leucocytes in the human body. She Ans : MAIN 2015

tabulated the pairs as follows: Plasma consists of water, proteins, and other
dissolved substances, while red blood cells contain
Leucocyte Function in the Body Hemoglobin and lack a nucleus. Thus (a) is the
P Engulfs and destroys correct option.
microorganisms
Q Produces antibodies to fight
infections
Identify the correct pair of leucocytes.
ONE MARK QUESTIONS
(a) P – Neutrophils, Q – Lymphocytes
(b) P – Monocytes, Q – Eosinophils
(c) P – Basophils, Q – Monocytes DIRECTION : Fill in the blanks :
(d) P – Lymphocytes, Q – Neutrophils
Ans : MAIN 2020
77. The smallest blood vessels in the human body.

Neutrophils are phagocytic cells that engulf Ans : SQP 2025

microorganisms, while lymphocytes produce Capillaries

antibodies to provide immunity. Thus (a) is the
correct option. 78. The contraction phase of the heart is______.
Ans : MAIN 2008
75. Priya tried to match the types of blood cells with
their production sites. She tabulated the pairs as Systole
follows:
79. The blood vessel that begins and ends in capillaries
Blood Cell Production Site is the______.
P Produced in the red bone marrow Ans : SQP 2011

Q Produced in lymphoid tissues Portal vein

Identify the correct pair of blood cells. 80. An artery which supplies blood to the liver
(a) P – Red Blood Cells, Q – White Blood Cells is______.
(b) P – White Blood Cells, Q – Red Blood Cells
(c) P – Red Blood Cells, Q – Platelets Ans : COMP 2003

(d) P – White Blood Cells, Q – Platelets Hepatic artery

Ans : SQP 2012
81. SA node is located on the wall of______.
Red blood cells are produced in the red bone
Ans : MAIN 2000
marrow, while white blood cells are produced
in both the bone marrow and lymphoid tissues. Right auricle
Thus (a) is the correct option.
82. _____is universal recipient blood group.
76. Priya tried to match the blood components with Ans : COMP 2017
their compositions. She tabulated the pairs as
follows: AB

Blood Cell Production Site 83. Irregular-shaped blood cells are______.

P Produced in the red bone marrow Ans : SQP 2023

Q Produced in lymphoid tissues WBC

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 229

124. A genetic disorder in which blood does not clot. Lymph

Ans : SQP 2022
135. An unstable bright red compound formed between
Hemophilia Hemoglobin and oxygen to carry the oxygento the
body cell.
125. The process by which WBCs engulf bacteria.
Ans : SQP 2022
Ans : MAIN 2019
Oxy Hemoglobin
Phagocytosis
136. The type of blood cells showing amoeboid
126. The opening through which the two auricles open movement.
into ventricle.
Ans : MAIN 2020
Ans : COMP 2017
WBCs
Auriculo-ventricular aperture
137. The site of production of RBC in the human
127. The instrument used for measuring heartbeat. embryo.
Ans : SQP 2014 Ans : COMP 2017

Stethoscope Spleen, Liver

128. The enzyme essential for blood clotting. 138. A disease in which the number of WBCs increase
Ans : MAIN 2009 at the cost of RBCs.
Thrombokinase Ans : SQP 2012

Leukaemia.
129. The site of production of red blood cells in the
adult human.
DIRECTION : Choose between the two options to
Ans : COMP 2007
answer the question specified in the brackets for the
Bone marrow following : An example is illustrated below. Example :
Corolla or Calyx (Which is the outer whorl ?) Answer
130. The type of blood group in which both A and B
: Calyx
antigens are present.
Ans : MAIN 2005 139. Blood in the renal artery or renal vein (Which one
Blood group-AB has more urea?)
Ans : COMP 2013
131. The process by which leucocytes squeeze out
through walls of capillaries. Blood in renal artery

Ans : SQP 2001 140. Blood in the pulmonary artery or pulmonary vein
Diapedesis (Which one contains less oxy hemoglobin?)
Ans : SQP 2018
132. The non-nucleated mature blood cells in mammals.
Blood in pulmonary artery
Ans : SQP 2013

RBCs
DIRECTION : Given below are sets of five terms
133. The respiratory pigment contained in human each. Rewrite the terms in correct order in a logical
blood. sequence. Example : Large intestine, Stomach,
Mouth, Small intestine, Oesophagus. Answer : Mouth
Ans : MAIN 2016
$ Oesophagus $ Stomach $ Small intestine $
Hemoglobin Large intestine.

134. The fluid that transports fatty acid and glycerol. 141. Fibrin, Platelets, Thromboplastin, Fibrinogen,
Ans : COMP 2019 Thrombin.
CH 7 : THE CIRCULATORY SYSTEM
Ans : COMP 2022
113. A fluid connective tissue.
Lymph Ans : SQP 2003

103. The valve located at the origin of aorta. Blood/Lymph

Ans : MAIN 2000
114. The element needed for blood clotting.
Aortic semi-lunar valve Ans : MAIN 2000

104. A vein that starts with capillaries and ends in Calcium

capillaries.
115. The minute blood vessels that join arteries and
Ans : COMP 2020
veins.
Portal vein Ans : COMP 2004

105. An artery which carries deoxygenated blood. Capillaries

Ans : SQP 2004
116. An organ that destroys worn out red blood cells.
Pulmonary artery Ans : SQP 2007

106. The phase of the cardiac cycle in which the auricle Liver
contact.
117. A blood vessel that supplies oxygen to the heart.
Ans : MAIN 2023
Ans : MAIN 2009
A trial diastole
Pulmonary vein
107. The phase of cardiac cycle in which the ventricles
relax. 118. The blood vessel which has valves in its inner
lining.
Ans : COMP 2021
Ans : SQP 2011
Ventricular diastole.
Vein
108. The membrane covering the heart.
119. Blood cells, the deficiency of which causes
Ans : SQP 2017
anaemia.
Pericardium Ans : MAIN 2013

109. The fluid present between the membrane covering RBCs

of heart.
120. The smallest blood vessels.
Ans : MAIN 2014
Ans : COMP 2015
Pericardial fluid
Capillaries
110. The valve present in between right atrium and
right ventricle. 121. The category of blood vessels which starts from
capillaries and ends in capillaries.
Ans : COMP 2010
Ans : MAIN 2018
Tricuspid valve
Portal vein
111. The blood vessel that brings blood from the body
parts to the heart. 122. The nearest organ to which the heart supplies
oxygenated blood.
Ans : MAIN 2008
Ans : MAIN 2020
Vena cava
Liver
112. An artery which carries deoxygenated blood.
123. The vitamin necessary for blood clotting.
Ans : COMP 2005
Ans : COMP 2023
Pulmonary artery Vitamin K
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 231

has thicker walls. The right ventricle has to pump WBC : Amoeboid shape
blood upto the lungs, so it has thinner walls.
164. State the main function of the Lymphocytes of
158. Mature erythrocytes in human lack nucleus and blood.
mitochondria.
Ans : SQP 2016
Ans : COMP 2017
Production of antibodies to provide specific
Lack of nucleus provides increased surface area immunity.
for absorbing more oxygen. Lack of mitochondria
helps to transport all the oxygen absorbed to 165. Differentiate LUBB and DUP (names of the
the tissues. Mitochondria are the site of cellular valves whose closure produce the sound) on the
respiration. basis of what is mentioned within bracket.
Ans : COMP 2016

DIRECTION : Complete the following statements by LUBB is produced due to the closure of AV valves
choosing the correct alternative out of those given in whereas DUP is produced due to the closure of
brackets : semi-lunar valves.

159. The wall of the heart is made up of ______ . 166. Bicuspid valve and Tricuspid valve. (Function).
(Striated muscle/Involuntary muscle/Cardiac Ans : MAIN 2013
muscle)
Ans : MAIN 2001 Bicuspid valve Tricuspid valve
Cardiac muscle Prevents the back flow Prevents the back
of oxygenated blood flow of de-oxygenated
160. Blood looks red because of the red coloured from left ventricle to blood from right
pigment ______ present in the blood cells. left auricle. ventricle to right
(Hemocyanin/Haemocoel/Hemoglobin) auricle.
Ans : COMP 2002
167. What are the two types of blood circulation in
Hemoglobin
humans ?
Ans : COMP 2021
DIRECTION : Write down the difference between
the following pairs as indicated within the brackets : (i) Pulmonary circulation
(ii) Systemic circulation
161. Erythrocytes and leucocytes (function) 168. Where is heart located?
Ans : SQP 2011
Ans : SQP 2014
Erythrocytes : Carry and supply oxygen to the Heart is located in the thoracic cavity in between
body. the two lungs.
Leucocytes : Kill foreign germs and act as
scavengers, soldiers of the body. 169. How is heart protected?
Ans : COMP 2018
DIRECTION : Answer the following :
It is protected by rib cage, pericardium layer and
pericardial fluid.
162. What is thrombosis ?
Ans : MAIN 2011
170. Mention the role of pericardial fluid.

Internal clotting of the blood is known as Ans : SQP 2009

thrombosis. It acts as a shock absorber and minimises the

friction due to the pumping of the heart.
163. Difference between RBC and WBC (Shape)
Ans : COMP 2015
171. Name the different types of corpuscles in the
blood.
RBC : Biconcave disc like in shape
CH 7 : THE CIRCULATORY SYSTEM

They help in blood clotting. Ans : COMP 2009

Semilunar
205. Tricuspid valve
Ans : COMP 2023
214. The thread-like structures that hold the cuspid
valves are ______.
It prevents the reverse flow of blood from the
right ventricle into the right auricle. Ans : MAIN 2011

Chordac tendinae
206. Chordae tendinae
Ans : MAIN 2020
215. The part of the blood from which fibrin is removed
______ .
To keep the cuspid valves in position.
Ans : SQP 2023
207. Vena cava Serum
Ans : SQP 2001
216. The largest artery is called ______ .
To carry deoxygenated blood from the body parts
to the right auricle of the heart. Ans : COMP 2015

Aorta
208. Lymphocytes.
Ans : COMP 2006
217. ______ are the blood corpuscles which destroy
microorganisms.
Lymphocytes produce antibodies for a particular
disease. Ans : COMP 2018

WBCs
209. A matured mammalian erythrocyte lacks nucleus
and mitochondria. 218. RBCs are ______ shaped.
Ans : MAIN 2016, 2011 Ans : SQP 2006

Lack of nucleus provides increased surface area for Biconcave

absorption of more oxygen. Lack of mitochondria
helps to transport all the oxygen absorbed to 219. The command for the heartbeat starts from
the tissue. Mitochondria are the site of cellular ______.
respiration. Ans : MAIN 2003

Pacemaker/S-AN
DIRECTION : Complete the following statements:
220. The blood vessel supplying blood to kidney
210. In human, heart has ______ chambers. is______.

Ans : SQP 2000 Ans : COMP 2001

Four Renal artery

211. The ______ walls are thin while the ______ 221. The blood vessel supplying blood to liver
walls are thick. is______.

Ans : MAIN 2004 Ans : MAIN 2014

Auricular, ventricular Hepatic artery

212. The right auriculo-ventricular aperture is guarded 222. The pulse rate of a normal adult human is
by a ______ valve. ______ per minute.

Ans : COMP 2017 Ans : SQP 2013

Tricuspid valve 72

213. The aorta and pulmonary artery are guarded by 223. The oxy Hemoglobin decomposes and liberates
______ valve. ______.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 233

and enters the lymphatic capillaries is called 194. Bicuspid valve

lymph. Lymph’s flow is unidirectional that is from
Ans : SQP 2017
lymph capillaries to lymphatic vessels and finally
into lymphatic duct which opens into the vein. It prevents the reverse flow of blood from the left
ventricle into the left auricle.
189. Complete the following table on mammalian
blood 195. Hemoglobin
Ans : MAIN 2022
Components Origin Function App. Life
No./mm3 span It is the respiratory pigment, helps to carry O2 to
the body parts.
RBC
WBC 196. Vitamin K

Platelets Ans : SQP 2002

Helps in clotting of blood.

Ans : MAIN 2003
197. Pericardium
Components Origin Function App. Life Ans : MAIN 2007
No./mm3 span
It protects the heart.
RBC Bone To carry 5 million 120
marrow O2 to days 198. Semilunar valves
the body
parts Ans : SQP 2004

WBC Bone To fight 7000 10 It guards the opening of pulmonary artery and
marrow against days aorta.
microor
ganisms 199. Lymph
Platelets Bone Clotting 2,50,000 2-3 Ans : MAIN 2010
marrow of blood days
It transports fatty acids and glycerol. It also
protects the body against microorganisms.
DIRECTION : Mention one function for each of the 200. WBCs
following :
Ans : COMP 2021

190. Lymphocytes To fight against microorganisms by producing

antibodies.
Ans : COMP 2021

Produce antibodies 201. Pulmonary artery

191. Thrombocytes Ans : SQP 2009

To transports deoxygenated blood to the lungs.

Ans : MAIN 2021

Clotting of blood 202. Fibrinogen

192. The wall of ventricles is thicker than auricles. Ans : MAIN 2004

It is a soluble blood protein needed for blood

Ans : COMP 2013
clotting.
To exert more pressure and to pump blood out of
the heart, the ventricles of the heart are thicker 203. RBCs
walled than auricles. Ans : SQP 2009

193. Neutrophils To transport oxygen to the body parts.

Ans : MAIN 2012
204. Thrombocytes
Phagocytosis Ans : MAIN 2017
CH 7 : THE CIRCULATORY SYSTEM
Ans : MAIN 2003
181. What is clotting of blood?
RBCs, WBCs and platelets. Ans : SQP 2004

172. Name the valves present in the heart. When blood comes out of the blood vessels due
to an injury, a series of changes takes place that
Ans : COMP 2001
transforms the blood fluid into jelly-like mass. This
Cuspid valves and semilunar valves. process is called coagulation or clot formation.
173. What is the function of valves in the heart? 182. Name the soluble protein present in blood plasma
Ans : SQP 2004 responsible for clotting.
They helps in the unidirectional flow of blood. Ans : MAIN 2002

Thus, prevents the backflow of blood. Fibrinogen and prothrombin.

174. What are the functions of arteries and veins? 183. What is a portal vein?
Ans : MAIN 2010 Ans : SQP 2004

Arteries carry oxygenated blood while veins carry A vein which starts from capillaries and ends in
deoxygenated blood. capillaries is called portal vein, e.g. hepatic portal
vein.
175. What are systole and diastole?
Ans : COMP 2017 184. What is pulmonary circulation?
Systole is the contraction phase of the heart and Ans : COMP 2009

diastole is the relaxation phase of the heart. Pulmonary artery carries deoxygenated blood
from the right ventricle to the lungs. Then from
176. What is serum?
the lungs, pulmonary vein transports oxygenated
Ans : SQP 2015 blood to the left auricle. This circulation is
Serum is the plasma from which fibrinogen is pulmonary circulation.
removed.
185. What is tissue fluid?
177. What is anaemia? Ans : MAIN 2000

Ans : MAIN 2009 Tissue fluid is the fluid filtered by the blood
It is the condition in which abnormal decrease in capillaries that are present around the tissue cells.
the number of RBCs occurs.
186. Define systemic circulation.
178. What is leukemia? Ans : COMP 2005

Ans : COMP 2007 Aorta transports oxygenated blood from the left
It is the increase in number of WBCs at the cost ventricle to the body parts, the deoxygenated
of RBCs. blood from the body returns to the heart through
the vene cavae. This circulation is called systemic
179. What is hemophilia? circulation.
Ans : MAIN 2006
187. What is Rh-factor?
It is a hereditary disease in which blood does not Ans : MAIN 2009
clot naturally.
Rh-factor depends on the presence of antigens on
180. Why is circulation of blood in human called the surface of RBC. If Rh antigen is present on
double circulation? the RBC of a person, then it is called as Rh+ and
if not it is called as Rh .
Ans : COMP 2001

Blood flows twice through the heart to complete 188. What is lymph?
one circulation. It includes pulmonary circulation Ans : COMP 2007
and systemic circulation.
The tissue fluid filtered from the blood capillaries
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 235
Ans : COMP 2018
False. WBCs are of several kinds.
Oxygen
233. New RBCs are produced in the heart.
224. The cell in which oxy Hemoglobin is formed is Ans : MAIN 2010
called______.
False. New RBC are produced in the bone marrow.
Ans : SQP 2000

RBC 234. Pulmonary vein carries oxygenated blood.

Ans : COMP 2019
225. The blood vessels which transport blood from the
heart to any organ is called______. True.

Ans : MAIN 2014 235. Mammals have open circulatory system.

Arteries Ans : SQP 2023

226. The blood vessel leaving the left ventricle of the False. Insects have open circulatory system.
mammalian heart is the______.
236. Three chambered heart is present in mammals
Ans : COMP 2019
Ans : MAIN 2012
Aorta
False. Four chambered heart is present in
227. Blood group ______ is universal recipient. mammals.

Ans : SQP 2021 237. Hemoglobin is found in WBC.

AB Ans : MAIN 2010

228. The normal human blood pressure is______ False. Hemoglobin is found in RBC.
mm of Hg.
238. The blood plasma from which fibrinogen has been
Ans : COMP 2012 removed is known as lymph.
120/80 Ans : COMP 2017

229. A full heartbeat in human beings takes about False. The blood plasma from which fibrinogen
______ second. has been removed is known serum.

Ans : MAIN 2016 239. The blood vessels which have valves in their inner
0.85 lining are called veins.
Ans : SQP 2001
230. The wall of heart is made up of______.
True.
Ans : SQP 2004

Cardiac muscle 240. Systolic pressure indicates the upper limit of

Blood Pressure.
231. ______ is an organ which serves as a blood Ans : MAIN 2020
reservoir during emergency.
True.
Ans : MAIN 2000

Heart 241. The blood group O is a universal donor.

Ans : COMP 2007

DIRECTION : State whether the following True.

statements are True or False. If false, correct and
rewrite the false statements by changing the first or 242. Iron is the mineral element responsible for the
last word only. clotting of blood.
Ans : MAIN 2009
232. RBCs are of several kinds.
False. Calcium is the mineral element responsible
Ans : COMP 2014 for clotting of the blood.
CH 7 : THE CIRCULATORY SYSTEM

THREE MARKS QUESTIONS neutralise the toxins (poisons) which are

released by infective bacteria. Antibodies are
also produced which destroy bacteria. The
289. Give one point of difference between the following antibodies stay in the blood for a long time
on the basis of what is indicated within brackets : to give built-in resistance (immunity) to a
(i) Red blood corpuscles and white blood particular disease.
corpuscles (function)
(ii) Blood and Lymph (composition)
(iii) Hemoglobin and Haemocyanin (pigment)
Ans : SQP 1997, 1996

(i) RBCs help in transport of oxygen and carbon

dioxide. WBCs help in protecting our body
against bacteria.
(ii)

Blood Lymph
291. The diagram given represents the double
Blood has a fluid Lymph is a light circulation in human begins.
matrix called plasma yellow fluid containing
and three kind of cells, lymphocyte cells.
i.e., RBCs WBCs and
platelets. Plasma is
colourless and contains
a lot of water and
many proteins.
(iii)

Hemoglobin Haemocyanin
1. A red respiratory A blue respiratory
pigment consisting pigment containing
of haem and the copper.
protein globin found
in the red blood
cells.
2. It is found in the It is found in the
blood of vertebrates blood of several
and a few inverte brates such
invertebrates, as molluscs and
crustaceans.

290. How skin and blood help in providing defence

mechanisms ?
Ans : COMP 1997

The body defends itself in a number of ways

against infection :
(i) Stomach acid kills microbes in food.
(ii) The skin forms a barrier against bacteria
entering the body. If the skin is broken, a
blood clot is formed to act as a barrier against
bacteria.
(iii) White blood cells produce antitoxins to
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 237

261. Coronary thrombosis DIRECTION : Distinguish between the following

pairs:
Ans : COMP 2019

It is a kind of heart attack in which a blood clot 268. Artery and Vein
is formed in the coronary artery.
Ans : MAIN 2010

262. RBC
Artery Vein
Ans : MAIN 2010
(a) It has thick (a) It has thin
One of the corpuscles present in blood which muscular wall. muscular wall.
contains Hemoglobin (the respiratory pigment)
RBC that helps in the transport of O2 to the body (b) Valves are (b) Valves are
parts. absent. present.
(c) Lumen is narrow. (c) Lumen is wider.
263. Pulse
Ans : SQP 2001 (d) It has an elastic (d) It has non-elastic
wall. wall.
The alternate expansion and contraction of the
wall of an artery with each systole and diastole of (e) It contains (e) It contains
the left ventricle is called pulse. oxygenated deoxygenated
blood. blood.
DIRECTION : Explain briefly : (f) It carries blood (f) It brings the
away from the blood to the
heart. heart.
264. Veins have valves in their inner lining while
arteries do not have valves. (g) It does not (g) It collapses when
collapse when empty.
Ans : COMP 2017
empty.
To prevent the backflow of blood. Since their
lumen is wider so they have valve, while arteries (h) Blood flows with (h) Blood flows
have narrow lumen. Blood in arteries flows with jerks under great continuously with
jerks so they do not have valves. pressure. low pressure.

265. The pulmonary artery contains deoxygenated 269. Red blood cell and White blood cell
blood.
Ans : SQP 2009
Ans : MAIN 2023

The pulmonary artery arises from the right Red Blood Cell White Blood Cell
ventricle which contains deoxygenated blood.
(a) It is biconcave (a) It is irregular in
266. Circulatory system is also known as ‘transport or disc-shaped. shape.
system’.
(b) It lacks nucleus. (b) Nucleus is
Ans : COMP 2020
present.
Circulatory system helps in the transport of O2,
CO2, hormones and collects metabolic wastes, etc. (c) It contains (c) Hemoglobin is
from all parts of the body. So, it is also known as Hemoglobin. absent.
‘transport system’.
(d) It helps in the (d) It protects our
267. Blood flows in arteries in spurts and is under transport of body against
pressure. oxygen. microorganisms

Ans : SQP 2016

270. Blood and Lymph
Arteries have to carry blood to longer distances.
So high pressure is needed. Ans : COMP 2002
CH 7 : THE CIRCULATORY SYSTEM

243. Pulmonary vein carries blood to the lungs. Platelets $ Thromboplastin $ Thrombin $
Fibrinogen $ Fibrin.
Ans : MAIN 2019

False. Pulmonary artery carry blood to the lungs.

DIRECTION : Define :
244. Vitamin E is needed for blood clotting.
253. Portal vein
Ans : SQP 2022

False. Vitamin K is needed for blood clotting. Ans : SQP 2017

A vein which starts from capillaries and ends in

245. Arteries ends in capillaries. capillaries is called portal vein. e.g. hepatic portal
Ans : MAIN 2020 vein.
True
254. Double circulation
246. Fibrinogen is an insoluble protein. Ans : MAIN 2017

Ans : COMP 2018 Blood flows twice in the heart before it completes
False. Fibrinogen is a soluble protein one full round which includes pulmonary and
systemic circulation.
247. Lymph transport respiratory gases.
Ans : SQP 2010 255. Diapedesis
True Ans : COMP 2002

The process of WBC squeezing out of capillaries

248. Systolic pressure shows the upper limit of blood
is called diapedesis.
pressure.
Ans : MAIN 2014 256. Phagocytosis
True Ans : SQP 2015

249. Pulmonary artery is the largest artery. The process of WBC engulfing microorganism is
called phagocytosis.
Ans : COMP 2002

False. Aorta is the largest artery 257. Systole

250. WBC’s can squeeze out of the capillaries. Ans : MAIN 2020

Ans : MAIN 2007 The contraction phase of the heart is called

systole.
True
258. Lymph
251. Thrombokinase is an enzyme needed for blood
clotting. Ans : COMP 2014

Ans : SQP 2013 The filtered blood plasma, which does not contain
RCBs is called lymph.
True
259. Diastole
DIRECTION : Given below are sets of five terms Ans : MAIN 2009
each. Rewrite the terms in correct order in a logical
The relaxation phase of the heart is called diastole.
sequence.Example : Large intestine, Stomach, Mouth,
Small intestine, Oesophagus.Mouth $ Oesophagus 260. Pulmonary circulation
$ Stomach $ Small intestine $ Large intestine
Ans : SQP 2017

252. Fibrin, Platelets, Thromboplastin, Fibrinogen, The circulation arising from the right ventricle
Thrombin. to the lungs and return back to the left auricle
through pulmonary artery and pulmonary vein
Ans : MAIN 2000
respectively.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 239

TWO MARKS QUESTIONS into glucose) with liver.

284. A mature mammalian erythrocyte lacks nucleus

278. Write any two functions of Lymph. and mitochondria but is efficient in its functioning.
Explain by giving suitable reasons.
Ans : SQP 2025
Ans : COMP 2021
Absorption of fats from intestines Drains excess
tissue fluid into blood Protects body from disease Loss of nucleus increases the surface area volume
causing germs. ratio of erythrocytes for absorbing more oxygen.
Loss of mitochondriae means erythrocytes can’t
279. Prothronibin, Thrombin, Fibrinogen, Albumin use oxygen for themselves so all oxygen is delivered
to the tissues unconsumed.
Ans : MAIN 2024

Odd One : Albumin 285. State the main function of the following :
Category : Others are clotting factors. (i) Coronary artery
(ii) Thrombocytes
280. Tonsils, Glomerulus, Spleen, Lymph nodes
Ans : SQP 2011
Ans : MAIN 2024
(i) Blood supply to the heart muscles
Odd one : Glomerulus (ii) Responsible for the blood clotting.
Category : Others are parts of lymphatic system.
286. What are the sounds produced during heart beat?
281. Mention two structural differences between an Ans : COMP 2008

artery and a vein. LUBB and DUP are the sounds produced during
Ans : MAIN 2024 contraction and relaxation of heart. Lubb is
produced by the closure of auricle ventricular
Differences between artery and vein:
valve, soon after ventricular systole begins. The
Artery Vein second. i.e., dub which is a short and sharp sound
which is produced due to the closure of semi-lunar
They have thicker walls. They have thinner valve.
walls.
They lack valves. They contain valves 287. What is the function of chordae tendineae ?
to prevent the Ans : MAIN 2005
backflow of blood.
Chordae tendineae are delicate, cord-like
structures connecting the papillary muscles with
282. Why are RBCs efficient in their functions though the valves of the heart. They prevent blood from
they lack nucleus and mitochondria? leaking back into the atria when the ventricles
Ans : MAIN 2024 contract.
Loss of nucleus : It makes the red blood cells 288. Give the location and functions of bicuspid and
biconcave thus, increasing their surface area tricuspid valve.
volume ratio for absorbing more oxygen.
lack of mitochondria : This means red cells cannot Ans : SQP 1997

use oxygen for themselves. Thus, all the oxygen (i) Bicuspid Valve : It is also called mitral valve.
absorbed from the lungs is transported and It consists of two flaps and is situated between
delivered to the tissues unconsumed. the left atrium and left ventricle. It prevents
any back flow of blood.
283. Name the blood vessel which has got the (i) Tricuspid Valve : It is a valve consisting of
maximum amount of glucose and give reasons for three flaps and is situated between the right
your answer. atrium and the right ventricle. It also prevents
Ans : MAIN 2011 any back flow of blood.
Hepatic portal vein has got the maximum amount
of glucose because it connects small intestine
(where all carbohydrates are finally converted
CH 7 : THE CIRCULATORY SYSTEM

Blood Lymph 274. Bicuspid valve and ‘bicuspid valve

(a) It is red in (a) It is colourless. Ans : SQP 2017

colour.
Bicuspid Valve Tricuspid Valve
(b) It contains (b) Hemoglobin is
(a) It guards the (a) It guards the
Hemoglobin. absent.
left auriculo- right auriculo-
(c) It contains (c) It contains ventricular ventricular
all types of lymphocytes, aperture. aperture.
corpuscles. erythrocytes are
(b) It has two leaf- (b) It has three leaf-
absent.
like flaps. like flaps.
(d) It contains more (d) It does not
proteins then contain 275. Pulmonary circulation and Systemic circulation
lymph. fibrinogen.
Ans : MAIN 2010

271. Auricles and Ventricles Pulmonary Systemic

Ans : MAIN 2006 Circulation Circulation
(a) In this (a) The oxygenated
Auricles Ventricles
circulation, blood is
(a) These are (a) These are the deoxygenated circulated into
the receiving distributing blood is pumped the body parts.
chambers chambers. into the lungs.
(b) Walls are thin. (b) Walls are thick. (b) The blood (b) The blood
(c) These are the (c) These are the coming back coming back
upper chambers lower chambers to the heart is to the heart is
of the heart. of the heart. oxygenated. deoxygenated.

272. Plasma and Serum 276. Plasma and Lymph

Ans : SQP 2009 Ans : SQP 2014

Plasma Serum Plasma Lymph

(a) It is the liquid (a) It is the filtered (a) It is straw (a) It is colourless
part of the blood. blood plasma. coloured.
(b) It does not (b) It does not (b) It circulates (b) It circulates
contain contain through blood through lymph
corpuscles. corpuscles and vessels. vessels.
fibrinogen.
(c) It is the liquid (c) It is the filtered
part of blood. blood plasma.
273. Diastole and Systole
Ans : COMP 2011 277. Pulmonary artery and Pulmonary vein

Diastole Systole Ans : MAIN 2005

(a) It is the (a) It is the

Pulmonary Pulmonary Vein
relaxation phase contraction
Artery
of the heart. phase of the
heart. (a) It arises from (a) It arises from
right ventricle. lungs.
(b) During diastole, (b) During systole,
blood flows into blood circulates (b) It carries (b) It carries
the body parts. through the deoxygenated oxygenated
heart. blood. blood.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 241

(i) Why is it called double circulation ? 293. Explain briefly the idea contained in the following
(ii) What is the difference in the composition statements :
of blood between pulmonary artery and (i) Counting pulse is the counting of heartbeat.
pulmonary vein ? (ii) Capillaries are thin walled.
(iii) Rewrite and complete the following sentences (iii) Vitamin K is required, for blood clotting.
by inserting the correct word in the space
Ans : COMP 1997, 1996
indicated.
The blood vessel that begins and ends in (i) The beating of the heart is also felt in the
capillaries is the______. arteries as regular jerks called the pulse. The
pulse can be felt in any artery that lie near
Ans : MAIN 2011
the surface of the body. The radial artery at
(i) Blood from right auricle goes to lung, gets the wrist is most commonly used for counting
purified, enters the left auricle and left pulse. The arteries have elastic muscular walls
ventricles. From heart to lungs and lungs to so they distend every time when blood is
heart, it is called pulmonary circulation. From forced through them due to the contraction of
heart purified blood passes into whole body. It the heart. Therefore it is said that, “counting
is called systemic circulation. Pulmonary and of the pulse is indirectly the counting of the
systemic together is called double circulation. heartbeat”.
(ii) Pulmonary artery contains deoxygenated (ii) With thin walls diffusion takes place more
blood while pulmonary vein contains readily and conveniently in capillaries.
oxygenated blood. (iii) Vitamin K is essential for the synthesis of
(iii) The blood vessel that begins and ends in prothrombin and fibrinogen proteins by the
capillaries is the Portal veins. liver cells. These proteins are essential for the
clotting of blood.
292. Give the composition and functions of blood.
294. How oxygen and food from the blood reach the
Ans : SQP 1997
cells ? Explain.
Blood consists of :
(i) Red blood cells : These cells carry oxygen Ans : MAIN 1997

from the capillaries in the lungs to the body (i) Oxygen and food molecules diffuse out of the
cells. The oxygen readily combines with blood into the tissue fluid which surrounds
Hemoglobin, a blood pigment in the cell, to every cell.
make oxyhaemoglo-bin. The shape of the red (ii) These substances then diffuse into the cell.
blood cell, a biconcave disc, provides a large (iii) Waste products diffuse out of the cell into
surface area to absorb as much oxygen as the tissue fluid and into the blood through
possible and has no nucleus, so allowing more the walls of the capillaries, to be carried away
space in the cell. from the cells to the excretory organs.
(ii) White blood cells : These cells protect the
body against disease by producing antibodies
to kill bacteria.
(iii) Plasma : This is a liquid which carries
the blood cells, platelets, dissolved food
substances, mineral salts, urea, carbon
dioxide, hormones, antibodies and antitoxins.
(iv) Platelets : These help in the clotting of the
blood. Functions of blood :
Circulation of blood is responsible for trans-
portation of: (1) nutrients, (2) respiratory
gases, (3) waste products, (4) hormones and
enzymes, and (5) ions from one part of the 295. Write briefly as indicated in the brackets, on the
body to the other. Blood also plays a role in following :
temperature regulation and protection of the (i) Red blood corpuscles (origin and function)
body from the attack of foreign bodies and (ii) Valves in the heart (location and function)
disease causing pathogens. (iii) Blood platelets (origin and function.)
CH 7 : THE CIRCULATORY SYSTEM

316. The diagram given below represents the human

heart in one phase of its functional activities.
Study the same and answer the questions that
follow:

315. Differentiate between vein and capillary.

Ans : MAIN 2011

The difference between vein and capillary are as

follows.

Vein Capillary
1. It is a thin 1. It is an extremely
walled blood narrow blood (i) Name the phase.
vessel. vessel having very (ii) Label the parts 1, 2, and 3.
thin walls. (iii) Which part of the heart is contracting in this
phase? Give a reason to support your answer.
2. It brings blood 2. It conveys blood (iv) Draw well labelled diagrams of part 1 and
from different which it receives 2 to show the structural differences between
parts of the from a small them.
body to the artery (called
heart. arteriole) and gives Ans : COMP 2013

up to a small vein (i) Atrical systole

(called venule). (ii) 1. Pulmonary artery
Capillaries form an 2. Superior vena cava
extensive network 3. Aorta
throughout all (iii) Auricles are contracting as cuspid valves are
living cells in the opened. Semi-lunar valves are closed.
body and connect (iv)
arteries and veins.
3. It cannot dilate 3. It can dilate or
or constrict, constrict according
to the requirement
of tissue.
4. It contains 4. It does not contain
simple valves any valves.
which permit 317. Study the following diagram carefully and then
blood-flow only answer the questions that follow :
towards heart
(one direction).
5. All veins except 5. Capillaries contain
pulmonary oxygenated
vein carry blood and are
deoxygenated responsible for the
blood. exchange of all (i) Name the cell labelled 1.
kind of substances (ii) Identify the phenomenon occurring in A.
between the blood (iii) Mention two structural differences between 1
and tissue fluids. and 2.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 243
Ans : COMP 2012
Lymph Tissue-Fluid
A human body has 5 litres of blood. When
Always travels in Never travels in two different groups of blood types are mixed,
Lymphatic vessels. vessels. erythrocytes clump together which is termed as
(viii) agglutination.
Pulmonary Systemic 301. Point out differences between an artery and a
Circulation vein.
1. Pumping of blood Pumping of blood Ans : COMP 2020
from right side of from left side of the
The difference between an artery and a vein are
heart to lung and heart to rest of the
as follows:
back to heart. body.
2. It carries It carries Artery Vein
deoxygenated oxygenated blood. (i) Arteries are (i) Veins are thin
blood. thick walled. walled.
(ix) (ii) Arteries carry (ii) Veins bring
blood from blood from
Auricle Ventricle
the heart to different parts
1. Auricle has thinner Ventricle has different parts of the body to
walls. thicker wall. of the body. the heart.
2. Auricle receives It distributes blood.
(iii) The blood (iii) The blood
blood.
flows with jerks flows smoothly
as they do not as they have
297. How does lymph flow? have valves semilunar
Ans : SQP 2017 valves which
prevent back
Lymph flows towards the heart from lymph
flow of blood.
capillaries into lymphatic vessels and into a
lymphatic duct which opens into a larger vein (iv) Arteries have (iv) Veins have
near the heart. narrow lumen wider lumen
298. How does hepatic portal system helps to reduce and are elastic. and are less
burden on the heart? elastic.
Ans : MAIN 2010
(v) Arteries are (v) Veins are
This system provides a short circuit for performing deeply seated superficial and
certain important functions (like monitoring and are red in lie just below
glucose level in the blood and detoxifying the colour. the skin. They
blood) before the blood reaches the heart. are greenish-
299. Why are pulmonary circulation and systemic blue in colour.
circulation called so? (vi) Arteries are (vi) Veins are
Ans : SQP 2023 non-collapsible. collapsible.
As blood from the right side of the heart reaches (vii) Arteries (vii) Veins contain
the left side through lungs, this part of blood become empty blood even
circulation is called pulmonary circulation. after death. after death.
Whereas, the blood from the left side of the heart
reaches the right side through various systems or (viii) All arteries (viii) All veins
body parts, this part of blood circulation is called except except
systemic circulation. pulmonary pulmonary
artery carry vein carry
300. How much blood does a human body have? What oxygenated deoxygenated
is meant by agglutination? blood. blood.
CH 7 : THE CIRCULATORY SYSTEM
Ans : COMP 1997
2. R.B.Cs are present R.B.Cs are absent
(i) Origin : Red cells are produced chiefly in in blood. in lymph.
the bone marrow of long bones (in adults).
Red cells are produced in liver and spleen, 3. Blood contains Lymph contains less
also in embryo. Function : RBCs carry more protein. protein.
oxygen and carbon dioxide. They help to 4. Blood platelets are Blood platelets are
maintain the acid-base balance. They help present. absent.
to maintain the viscosity of blood. Various (iii)
pigments are derived from Hemoglobin after
the disintegration of the red blood cells, e.g., RBC WBC
bilirubin. biliverdin, etc.
1. Biconcave, circular, Irregular in shape
(ii) Location : Valves are present between left
non- nucleated. or round with
atrium and left ventricle and between right
nucleus.
atrium and right ventricle.
Function : Valves permit the flow of blood 2. Hemoglobin is Hemoglobin is
from atrium to ventricle and not in the present. absent.
reverse order. 3. Produced in red Produced in red
(iii) Origin : They are produced in the red bone bone marrow. bone marrow,
marrow from some giant cells called mega- spleen and liver.
karyocytes. Function : The blood platelets
(iv)
are responsible for the clotting of blood at
injuries. Blood platelets on disintegration Diastole Systole
produce a chemical called thromboplastin
that initiates the chain of reactions involved 1. Phase of the heart The phase of the
in blood clotting. beat cycle when heart beat cycle
the cardiac muscle when the cardiac
296. Write difference between the following pairs : is relaxed. muscle contracts.
(i) Artery, Vein; (ii) Blood, Lymph; (iii) RBC, 2. Chambers are Chambers expel the
WBC; (iv) Diastole, Systole; (v) Mitral Valve, filled with blood. blood from auricles
Semilunar Valve; (vi) Blood Plasma, Serum; to ventricles, and
(vii) Lymph, Tissue Fluid; (viii) Pulmonary from ventricles
Circulation, Systemic; (ix) Auricle, Ventricle. to aorta and
Ans : MAIN 2002 pulmonary artery.
(i) (v)

Artery Vein Mitral Valve Semi-lunar Valve

1. Carries oxygenated Carries 1. It is present Present between
blood. deoxygenated blood. between left auricle openings of aorta
and left ventricle. and left ventricle
2. Artery has no valve. Vein has got valve.
and pulmonary
3. Artery carries blood Veins carry blood artery and right
away from the towards heart. ventricle.
heart.
2. It consists of a pair It is semi-lunar.
4. Lumen is narrow in Lumen is broad in of flaps.
an artery. a vein.
(vi)
5. It is deeply seated. Superficial.
Blood Plasma Serum
(ii)
1. Fibrinogen is Fibrinogen is
Blood Lymph present. absent.
1. Red in colour. White or yellowish (vii)
in colour.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 245

(iii) False. The blood contains an anticoagulant Ans : SQP 2025

heparin (antithrombin) that prevent clotting The circulatory system ensures the distribution
of blood within the blood vessels. of nutrients and oxygen to the body through the
following steps:
(i) Heart as the Pump : The heart acts as a
central pump, propelling oxygenated blood
FIVE MARKS QUESTIONS from the lungs and nutrient-rich blood from
the digestive system to all parts of the body.
(ii) Transport Through Arteries : Oxygenated
307. The diagrams given below are cross-sections of blood is transported via arteries, which
blood vessels : branch into smaller arterioles and capillaries.
(i) Identify the blood vessels A, B and C. These capillaries reach tissues and cells.
(ii) Name the parts labelled 1 to 3. (iii) Exchange at the Capillary Level : In the
(iii) Name the type of blood that flows through A. capillaries, oxygen and nutrients diffuse from
(iv) Mention one structural difference between A the blood into body cells. Simultaneously,
and B. waste products like carbon dioxide diffuse
(v) In which of the above vessels does exchange of from cells into the blood.
gases actually take place? (iv) Return Through Veins : Deoxygenated blood
carrying carbon dioxide and waste products
is transported back to the heart through
veins and is then pumped to the lungs for
oxygenation.
(v) Continuous Cycle : This process repeats
continuously, ensuring that every cell in the
body receives oxygen and nutrients while
removing waste efficiently.
Ans : MAIN 2015
309. Study the diagram carefully and answer the
(i) A – Artery
following questions.
B – Vein
C – Capillary
(ii) 1 – Tunica externa/External layer
2 – Lumen
3 – Tunica media / middle layer
(iii) Oxygenated blood
(iv) The structural difference between A and B
are as following :

A B
Thick walled – Thin walled
Narrow lumen – Wider lumen (i) Label the guidelines 1-11.
(ii) Give one function of parts labelled as 1, 3, 6,
No valves present – Valves present 8 and 11.
Not collapsible – Collapsible Ans : SQP 2011
Progressively – Progressively
(i) 1. Right ventricle 2. Tricuspid valve
branched – unite
3. Right atrium 4. Venacava
Smallest artery – Smallest vein
5. Pulmonary 6. Aorta
breaks into arteriole – arises from venules artery
(v) C – Capillary 7. Pulmonary vein 8. Left atrium
308. How does the circulatory system work to distribute 9. Semilunar valve 10. Bicuspid valve
nutrients and oxygen? 11. Left ventricle
CH 7 : THE CIRCULATORY SYSTEM

302. What is Plasma ? What are the various functions entangled and form a Blood Clot.
of Plasma ? Given below is a flow chart showing major
events in blood coagulation :
Ans : SQP 2021
Injured tissues + Blood platelets " Release
Plasma is a colourless fluid in which blood thromboplastin.
cells float. It contains mainly water (90%) and Prothrombin
Thromboplastin
Thrombin
dissolved substances (10%). These substances Fibrinogen
Thrombin
Fibrin.
include proteins, fats, mineral salts, glucose, Fibrin + Red blood corpuscles " Blood Clot.
antibodies, urea, hormones and traces of many (ii)
other substances.
Functions of plasma:
(i) Transportation of digested food and metabolic
wastes.
(ii) Transportation of oxygen and carbon dioxide.
(iii) Transportation of hormones.
(iv) Distribution of body heat and maintaining
body temperature.
(v) Transportation of hormones.
(vi) Maintenance of water level in the cells.
(vii)Maintaining steady state of the body (also
called homeostasis).
DIRECTION : The first pair indicates the kind of
303. What is the meaning of the term “double relationship that exists between both the terms.
circulation”?
Ans : MAIN 2014 305. Rewrite and complete the second pair on a similar
basis.
The blood flows twice through the heart and it is
(i) Veins : Superficial : : Artery : _____
called double circulation.
(ii) RBC: Round : : WBC: _____
(i) The blood from all body parts is brought
(iii) Artery: Oxygenated blood : :Vein : _____
to right auricle which pumps it into right
(iv) Auricles : Receiving chambers : : Ventricles
ventricle. From right ventricle blood is
:_____
pumped to lungs (through pulmonary artery)
(v) Lubb : Atrioventicular valves : : Dub :_____
for oxygenation. [This is first circulation]
(ii) The oxygenated blood from lungs is brought Ans : COMP 2004
to left auricle which pumps it into left (i) Deeply seated
ventricle. From the left ventricle oxygenated (ii) Irregular
blood is distributed to all the parts of the (iii) Deoxygenated blood.
body through largest artery called aorta. (iv) Distributing chambers.
[This is second circulation] (v) Semilunar valves.
304. (i) Write a note on mechanism of blood clotting. 306. Mention if the following statements are true or
(ii) Show diagramatically the contraction and false :
relaxation stages of ventricle. (i) Average life of a red blood cell in our body is
Ans : COMP 2017 about 120 hours
(ii) The substances which prevent clotting of
(i) When blood flows out of a damaged blood
blood are called coagulants.
vessel, blood platelets release a substance
(iii) The blood contains an anticoagulant thrombin
called Thromboplastin. In the presence of
which prevent clotting of blood within the
calcium and thromboplastin, Prothrombin
blood vessels.
present in blood gets converted into thrombin.
Thrombin then catalyses the conversion of Ans : MAIN 1995
fibrinogen present in plasma into Fibrin. (i) False. Average life of a red blood cell in our
Fibrin is the ultimate product which forms body is 120 days.
a mesh, into which red blood corpuscles get (ii) False. They are called anticoagulants.
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 247

(i) Name the blood vessels labelled 1, 3, 6, and 7. Since tricuspid and bicuspid valves are open
(ii) Name the blood vessel that supplies the walls while pulmonary semilunar valve and aortic
of the heart with oxygen. semilunar valves are closed.
(iii) Draw a neat labelled diagram of the blood (iv)
vessel numbered ‘2’ as seen in a cross-section.
(iv) Mention one structural difference between
blood vessels numbered 4 and 5.
Ans : COMP 2013

(i) Pulmonary vein (3) – Hepatic Portal vein (6)

Hepatic vein (7) Inferior vena cava
(ii) Coronary artery
(iii)

314. The diagram given below represents a section of the

human heart. Answer the questions that follow :

(iv) Arteries are very thick walled with narrow

lumen whereas veins are thin walled with
wide lumen.

313. The diagram given below represents the human

heart in one phase of its functional activities.
Study the same and answer the questions that
follow :

(i) Which parts of heart are in the diastolic

phase? Give a reason to support your answer.
(ii) Label the parts numbered 1 and 2 in the
diagram. What type of blood flows through
them?
(iii) What causes the heart sounds ‘TUBB’ and
‘DUP’ ?
(iv) Name the blood vessels that supply
oxygenated blood to the heart muscles.
(v) Draw neat labelled diagrams of a cross-section
of an artery and a vein.
(i) Name the phase.
Ans : SQP 2017
(ii) Label the parts 1, 2, and 3.
(iii) Which part of the heart is contracting in his (i) Ventricles, as the blood is flowing towards
phase ? Give a reason to support your answer. ventricle since tricuspid and bicuspid valves
(iv) Draw well-labelled diagrams of part 1 and 2 are open.
to show the structural differences between (ii) 1. Pulmonary artery
them. 2. Left pulmonary veins.
(iii) The LUBB sound is caused due to the closure
Ans : MAIN 2013
of the auriculo-ventricular valves while DUP
(i) Auricular systole and ventricular diastole. sound is caused due to the closure of the
(ii) 1. Pulmonary artery semilunar valve.
2. Superior/anterior vena cava (iv) Coronary arteries supply oxygenated blood to
3. Aorta the heart muscles.
(iii) Auricles. (v)
CH 7 : THE CIRCULATORY SYSTEM

(ii) 1. Right ventricle : Pumps the blood to the (iii) Deoxygenated blood.
lungs via pulmonary artery. (iv) Inferior vena cava has valves and a wider
3. Right atrium : Takes in deoxygenated lumen whereas Dorsal aorta has no valves
blood which has been brought from the and a narrow lumen.
entire body by main vein.
6. Aorta : Thick-walled main artery which 311. The diagrams given below are cross sections of
distributes the blood throughout body. blood vessels:
8. Left atrium : Receives oxygenated blood
from the lungs via the pulmonary vein.
11. Left ventricle : Pumps the blood under
great pressure around the body via the
aorta.

310. Given diagram is the external features of the

heart : (i) Identify the blood vessels A, B and C.
(ii) Name the parts labelled 1 to 3.
(iii) Name the type of blood that flows through A.
(iv) Mention one structural difference between A
and B.
(v) In which of the above vessels does exchange of
gases actually take place?
Ans : MAIN 2015

(i) A. Artery B. Vein C. Capillary

(ii) 1 – Connective tissue
2 – Lumen
3 – Muscular wall
(iii) Oxygenated blood passes through artery.
(iv)

Artery Vein
(i) Name the parts ‘1’ to ‘7’. 1. Muscular wall is thick Muscular wall is
(ii) What happens if the coronary artery gets an thin
internal clot ? 2. Has a narrow lumen Has a wider lumen.
(iii) What type of blood does ‘5’ carry?
(iv) Mention one structural difference between ‘5’ (v) Blood vessel C.(Capillary)
and ‘4’. 312. The diagram below represents circulation in the
Ans : COMP 2010 human body. Answer the questions that follow :

(i) 1. Aorta 2. Left auricle

3. Left ventricle 4. Dorsal Aorta
5. Inferior 6. Superior
venacava venacava
7. Pulmonary
arch
(ii) Coronary artery supply blood to the muscles
present in the inner lining of the heart. If it
gets an internal clot then blood supply will
get stopped to the muscles and they will stop
functioning. As a result of this heart will not
function.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 249

(iv) Name the process occurring in B and C and (v) Loss of Nucleus increases their surface area for
state the importance of this process in the absorbing more oxygen, loss of mitochondria
human body. means RBCs cannot use oxygen for themselves
and loss of endoplasmic reticulum increases
Ans : SQP 2011
flexibility of RBCs for their movement
(i) RBC through narrow capillaries.
(ii) Diapedesis
(iii) 319. Given diagram is the longitudinal section of
human heart.
1 – RBC 2 – WBC
– Biconcave or disc- – Irregular in shape
shaped
– Mature RBC does – WBC contains
not contain nucleus. nucleus
(iv) Phagocytosis – WBC engulfs microorganisms
that enter into the body and acts as the
deference system.

318. Given below is a diagram of a human blood smear.

Study the diagram and answer the questions that
follow :
(i) Label the guidelines 1-10.
(ii) Name the place where pacemaker is situated.
(iii) What is the difference in composition of blood
in 4 and 5 ?
(iv) How many valves are present in the above
diagram?
(v) Name them.
Ans : COMP 2021

(i) 1. Aorta
2. Anterior venacava
(i) Name the components numbered ‘1’ to ‘4’. 3. Posterior venacava
(ii) Mention two structural differences between 4. Left pulmonary artery
the parts ‘1’ and ‘2’. 5. Pulmonary vein
(iii) Name the soluble protein found in part ‘4’ 6. Right auricle
which forms insoluble threads during clotting 7. Right ventricle
of blood. 8. Left auricle
(iv) What is the average lifespan of the component 9. Left ventricle
numbered ‘1’ ? 10. Tricuspid valve
(v) Component numbered 1’ do not have certain (ii) In the wall of right auricle.
organelles but are very efficient in their (iii) The blood vessel 4 has got deoxygenated
function. Explain. blood while blood vessel 5 has got oxygenated
Ans : MAIN 2018
blood.
(iv) Four.
(i) 1. Red blood cells/Erythrocytes (v) Bicuspid, tricuspid and two semi-lunar valves.
2. White blood cells/Leucocytes
3. Platelets/Thrombocytes 320. Briefly describe the functions of blood.
4. Blood plasma
Ans : MAIN 2023
(ii) RBC : Don’t have nucleus
WBC : Nucleus present Blood is a liquid connective tissue which is
Biconcave disc like Amoeboid in shape. pumped by the heart and flows through the blood
(iii) Fibrinogen vessels like artery, veins and capillaries. It has got
(iv) 140 days the following functions:
CH 7 : THE CIRCULATORY SYSTEM

(ii) Based on their structure: (b) WBCs (Leucocytes) : They are

1. Right auricle – Walls are thin colourless, irregular in shape with a
Left ventricle – Walls are thick nucleus which may be irregular in shape.
Nature of blood: They are mainly of two types. The first
2. Right auricle – Deoxygenated blood one is granulocytes in which cytoplasm
Left ventricle – Oxygenated blood is granular and lobed nucleus while
(iii) Pulmonary circulation agranulocytes are without granules and
(iv) Aortic semi-lunar valve nucleus without lobes. Agranulocytes
and granulocytes are further subdivided
325. Comment briefly on the structure and composition into many other types. The WBCs are
of blood in a chart form. produced in the red bone marrow, lymph
Ans : SQP 2005 nodes, spleen and liver. The lifespan of
WBCs is usually two weeks. Their main
Blood is a viscous complex tissue fluid, red in
function is phagocytic, i.e., they protect
colour. It is salty in taste, alkaline with pH
our body from diseases.
ranging from 7.3 to 7.5. Blood contains the liquid
part called plasma in which solid particles like (c) Platelets (Thrombocytes) : They are
corpuscles are found suspended but unattached small colourless flat granular corpuscles
to each other. which are smaller than RBCs. They are
(i) Plasma : It is the complex sticky aqueous present in red bone marrow and contain
solution of straw colour which forms 55% thromboplastic substance which helps in
of the total volume of the blood. It contains clotting of blood. The lifespan of platelets
a liquid known as serum and a coagulative is only 2-3 days. They are without nucleus
substance called fibrinogen. It also contains and oval to spherical in shape.
inorganic and organic substances.
(a) Inorganic substances include chloride,
bicarbonates, phosphates and sulphates of
sodium, potassium, calcium, magnesium
and iron. These are most essential
components of blood which help in the
normal functioning of the body tissue.
(b) Organic components of plasma include
a variety of plasma protein such as
fibrinogen, albumins and globulins. Other
organic substances include glucose, amino
acids, fats, vitamins, hormones, urea, uric
acid, etc.
(ii) Corpuscles or Blood cells : 45% of blood
constitutes the corpuscles. They are mainly
of three types :
(a) RBCs (Erythrocytes) : They are red in
colour, biconcave and circular without any 326. The diagram below represents a certain category
nucleus, mitochondria and endoplasmic of blood vessels showing the role of special
reticulum. They are produced in the structure in their walls:
bone marrow of bones such as ribs, (i) Name the kind of blood vessels shown.
vertebrae and skull. They contain one (ii) Name the structure shown inside the blood
iron pigment called Hemoglobin which vessels.
carry oxygen supply to all living cells for (iii) Describe the role of these structures.
cellular respiration. Their lifespan is 120
days. In addition to their main function,
i.e., supplying O2 to the tissue, they also
transport CO2 from tissues to lungs,
maintain the pH of blood, viscosity of
blood.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 251

(e) The heart is covered by a double membranous (iii) LUBB sound is produced when the auricular-
layer called pericardium. It is filled with ventricular valves get closed at the start of
pericardial fluid which protects the heart the ventricular systole.
from shocks and jerks. DUP sound is produced when the semi-lunar
(f) The left ventricle has to pump the blood to a valves get closed at the start of ventricular
greater distance with great force. That is why diastole.
it has got the thickest wall compared to the (iv) Coronary artery.
other chambers of the heart. (v)
(g) The element present in Hemoglobin is iron
and protein is globin.
(h) Nucleus, mitochondria and endoplasmic
reticulum are absent in RBC but present in
all other cells.

323. The diagram given below represents a section of

the human heart. Answer the question that follow:

324. Given diagram is a schematic representation of

the circulatory system in man. Study the same
and answer the questions that follow:

(i) Which parts of heart are in the diastolic

phase? Give a reason to support your answer.
(ii) Label the parts numbered 1 and 2 in the
diagram. What type of blood flows through
them?
(iii) What causes the heart sounds ‘LUBB’ and
‘DUP’ ? (i) Label the parts 1 to 4 indicated in the
(iv) Name the blood vessels that supply diagram.
oxygenated blood to the heart muscles. (ii) Give one difference between the parts 1 and
(v) Draw neat labelled diagrams of a cross section 2 based on : (1) their structure (2) the nature
of an artery and a vein. of blood flowing through them.
Ans : MAIN 2017 (iii) What is the specific name of the type of blood
circulation that takes place between the heart
(i) Ventricles.
and the lungs?
The reasons are : Cuspid valves are opened,
(iv) Name the valve found at the beginning of the
Semi-circular valves are closed and Auricular
part labelled 3.
muscles contract.
(ii) 1. Pulmonary artery. Ans : COMP 2019
2. Pulmonary veins. (i) 1. – Right auricle
Pulmonary artery contains deoxygenated 2. – Left ventricle
blood while pulmonary veins contain 3. – Aorta
oxygenated blood. 4. – Body parts
CH 7 : THE CIRCULATORY SYSTEM

(a) It supplies all essential chemical substances (iv) What is the average lifespan of the component
like amino acids, glucose, etc., to the cells of numbered ‘1’ ?
the body which are required for their normal (v) Component numbered 1’ do not have certain
metabolism. organelles but are very efficient in their
(b) It transports oxygen to all living cells for function. Explain.
tissue respiration.
Ans : SQP 2018
(c) It removes carbon dioxide from all cells which
are produced during metabolism. The carbon (i) 1. Red blood cells/Erythrocytes
dioxide is removed as bicarbonate which are 2. White blood cells/Leucocytes
dissolved in blood plasma. 3. Platelets/Thrombocytes
(d) It distributes hormones to all parts of the 4. Blood plasma
body from the endocrine glands. (ii) RBC : Don’t have nucleus
(e) It prevents our body from infections caused WBC : Nucleus present
by pathogens. WBC acts as phagocytes and Biconcave disc like Amoeboid in shape
engulfs these pathogens and protect us from (iii) Fibrinogen
diseases. (iv) 140 days
(f) White blood corpuscles of blood (WBCs) (v) Loss of Nucleus increases their surface area for
also secrete into the plasma the antibodies absorbing more oxygen, loss of mitochondria
which are chemical substances capable of means RBCs cannot use oxygen for themselves
neutralizing toxic substances in blood secreted and loss of endoplasmic reticulum increases
by the bacteria. flexibility of RBCs for their movement
(g) Blood helps in maintaining normal body through narrow capillaries.
temperature.
322. Answer the following questions :
(h) It keeps the homeostasis of the tissue fluid,
(a) Name the veins which carry pure blood.
acid base balance and osmoregulation in the
(b) Name an artery which carries impure blood.
body.
(c) What is a pacemaker ?
(i) It helps in the formation of clot in the injured
(d) A matured mammalian erythrocyte lacks
tissue. Thus, it prevents further bleeding.
nucleus and mitochondria. Give reasons.
(j) It removes urea, uric acid and other poisonous
(e) How is heart protected from shocks and jerks?
substances from liver and throws them into
(f) Why is the wall of the left ventricle the
kidney from where they are removed through
thickest?
urine.
(g) Name the element and protein present in
(k) Blood in the arteries is under pressure which
Hemoglobin.
helps to support the tissues.
(h) Name three structures which are present in
321. Given below is a diagram of a human blood smear. all living cells but absent in RBC.
Study the diagram and answer the questions that
Ans : COMP 2012
follow:
(a) Pulmonary veins.
(b) Pulmonary artery is the only artery which
carries impure blood from right ventricle to
the lungs for purification. All other arteries
carry pure or oxygenated blood. All veins
carry impure blood or deoxygenated blood to
the heart except pulmonary vein.
(c) The pacemaker is the sinoatrial node (SAN)
located in the wall of right auricle near the
point of entry of the venacava. Impulses
(i) Name the components numbered ‘1’ to ‘4’. for contraction and relaxation of the heart
(ii) Mention two structural differences between originate in the pacemaker or sinoatrial node.
the parts ‘1’ and ‘2’. (d) The erythrocyte lacks nucleus and
(iii) Name the soluble protein found in part ‘4’ mitochondria to make the space for
which forms insoluble threads during clotting accomodating large quantity of Hemoglobin.
of blood.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 253

(i) 1. – RBC; 2. – WBC; 3. – Platelets; 4. –

Plasma.
(ii)

RBC WBC
(1) Non-nucleated (1) Nucleated

(2) Biconcave, disc- (2) Irregular in

like shape

(iii) 1 - Transports oxygen to all parts of the body.

(iv) Are these structures present in any other kind
2 - Protects the body by destroying harmful
of blood vessel? If so, name it.
microorganisms.
(v) Towards which side of the figure (top or
3 - Clotting of blood.
bottom) is the heart located?
(iv) 120 days
Ans : SQP 2013 (v) Fibrinogen
(i) Veins (vi) Hemophilia
(ii) Valves 328. Given below is a diagram of the external features
(iii) Blood flowing through the veins is at low of the heart.
pressure and moving against gravity, hence it
tends to flow downwards, filling the pocket-
shaped valves which close, thereby preventing
the backflow of blood.
(iv) Yes, at the opening of aorta and pulmonary
artery.
(v) Top

327. Given below is a diagram of a smear of human

blood. Study the same and then answer the
questions that follow:

(i) Name the parts 1 to 7.

(ii) What happens if the coronary artery gets an
internal clot?
(iii) What type of blood does 5 carry?
(iv) Mention one structural difference between 5
and 4.
Ans : MAIN 2017
(i) Name the parts 1, 2, 3 and 4 indicated by
guidelines. (i) 1 - Aorta; 2 - Left atrium; 3 - Left ventricle;
(ii) Mention two structural differences between 4 - Dorsal aorta; 5 - Inferior vena cava; 6 -
the parts labelled ‘1’ and ‘2’. Superior vena cava; 7 - Pulmonary artery.
(iii) What is the main function of the parts (ii) If the coronary artery gets a clot the
labelled 1, 2 and 3? corresponding part of the heart does not get
(iv) What is the life span of the part labelled ‘1’ ? blood supply. It may cause death of the cells
(v) Name a soluble protein found in ‘4’ which of the heart and may cause heart attack.
helps in the clotting of blood. (iii) ‘5’ carries deoxygenated blood.
(vi) Name the disease in which blood fails to clot (iv) ‘5’ is vena cava which has thin muscular walls
naturally. while ‘4’ is aorta which has thick muscular
Ans : MAIN 2009 walls.
CH 7 : THE CIRCULATORY SYSTEM

involved in forming a clot and how this mechanism 4. Matching

prevents excessive bleeding during injuries.
1. Describe the process of blood clotting and the 339. Dr. Sharma discusses the lymphatic system’s
role of platelets. importance in immunity and fluid balance with
2. What are the steps involved in the formation Mr. Verma. She describes how lymph nodes filter
of a blood clot? lymph fluid and how lymphocytes work to protect
3. How do anticoagulants function in the body? the body from infections.
4. Discuss the significance of Vitamin K in blood 1. How do lymphocytes contribute to the
clotting. immune response?
2. What is the function of lymph nodes in
Ans : filtering lymph?
1. Coagulation 3. Discuss the relationship between the
2. Cascade lymphatic and circulatory systems in immune
3. Prevention function.
4. Synthesis 4. What are common disorders associated with
the lymphatic system, and how do they affect
337. Mr. Verma visits Dr. Sharma after experiencing immunity?
chest pain, and she discusses the implications of
heart conditions. She explains that a heart attack Ans :
can occur if blood flow to the heart muscle is 1. Antibodies
blocked, leading to potential damage. 2. Protection
1. What is a myocardial infarction, and how 3. Cooperation
does it affect the heart? 4. Lymphedema
2. Discuss the symptoms and risk factors
associated with heart disease.
3. How can lifestyle changes reduce the risk of www.nodia.in
heart disorders?
4. What role do diagnostic tests play in
identifying heart conditions?
Ans :
1. Blockage
2. Angina
3. Exercise
4. Detection

338. During a health seminar, Dr. Sharma explains

the importance of blood types and compatibility
during transfusions. She emphasizes the
significance of understanding ABO and Rh factors
in preventing adverse reactions.
1. What are the different blood groups, and how
are they determined?
2. Explain the significance of the Rh factor in
blood transfusions.
3. How does blood type compatibility affect the
outcome of a transfusion?
4. What precautions should be taken during
blood transfusions to prevent agglutination?
Ans :
1. Antigens
2. Compatibility
3. Reactions
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 255

CASE BASED QUESTION (ii) Calcium

(iii) Heparin
(iv) The platelets release an enzyme in the injured
332. Dr. Sharma explains to Mr. Verma how the heart place called thrombokinase. It converts
pumps oxygenated blood and how the circulatory prothrombin into thrombin. In the presence
system functions. The heart, a vital organ, is of Ca++, thrombin reacts with fibrinogen to
responsible for maintaining blood flow throughout convert it into fibrin. Corpuscles are trapped
the body. It ensures that oxygen and nutrients inside the mesh work of fibrin and form the
are delivered to tissues while waste products are clot. The clear liquid left out is the serum.
removed.
1. What is the primary function of the heart in 334. During a health check-up, Mr. Verma learns from
the circulatory system? Dr. Sharma about the components of blood and
2. Describe the flow of blood through the heart's their vital roles in the body. Blood serves multiple
chambers. functions, including transporting oxygen and
3. Explain the roles of arteries, veins, and nutrients, removing waste, and providing defense
capillaries in circulation. against infections.
4. What is the significance of a closed circulatory 1. What are the main components of blood and
system in vertebrates? their functions?
2. How does blood regulate body temperature
Ans : and pH levels?
1. Pumping 3. Discuss the role of Hemoglobin in oxygen
2. Circulation transport.
3. Transport 4. How does blood protect the body against
4. Efficiency infections?
Ans :
333. In a biology lab, students examine a diagram of
blood coagulation. The instructor discusses the 1. Cells
components involved in clotting and their roles 2. Homeostasis
in preventing excessive bleeding. Students must 3. Binding
analyze the figure and answer the following 4. Immunity
questions.
335. Dr. Sharma informs Mr. Verma about lymph nodes
and their role in immune response, emphasizing
the lymphatic system's function in removing
waste. She explains that lymph fluid is essential
for transporting immune cells and maintaining
fluid balance in the body.
1. What is the role of lymph in the body?
2. Describe the structure and function of lymph
nodes.
3. How do lymphatic vessels assist in maintaining
fluid balance in the body?
4. What is the importance of lymphocytes in
the immune response?
(i) Label the parts 1-4.
(ii) Name the element needed for clotting. Ans :
(iii) Name the chemical which prevents the 1. Drainage
clotting of blood inside the blood vessels. 2. Filtering
(iv) Briefly explain the process of blood clotting. 3. Absorption
Ans : SQP 2004 4. Defense
(i) 1 – Corpuscles; 336. Dr. Sharma explains to Mr. Verma how blood
2 – Fibrin threads; clotting occurs and the importance of platelets
3 – Serum; in this process. She highlights the critical steps
4 – Clot
CH 7 : THE CIRCULATORY SYSTEM

329. Given below is a diagrammatic sketch of blood (d) Which vessel will contain the smallest
vessels: number of red blood cells per unit volume
of blood?
(e) In which vessel will the blood carry the
most oxy Hemoglobin?
Ans : COMP 2005

(i) 1 - Pulmonary vein

2 - Aorta
3 - Hepatic artery
(i) Label the parts 1 to 8. 4 - Hepatic portal vein
(ii) What is the difference in the quality of blood 5 - Renal artery
contained in 1 and 5? 6 - Renal vein
(iii) Name any one important component of the 7 - Hepatic vein
blood which remains inside the capillary and 8 - Vena cava
fails to move out into the spaces. 9 - Pulmonary artery.
(ii) (a) Renal artery
Ans : SQP 2014 (b) Hepatic portal vein
(i) 1 - Artery (c) Hepatic portal vein
2 - Arteriole (d) Hepatic vein
3 - Capillary (e) Pulmonary vein
4 - Venule
331. Given below is the diagram to show the movement
5 - Vein
of blood in the vein towards the heart:
6 - Lymphatic vessel
7 - Lymph
8 - Cell.
(ii) 1 - Artery contains oxygenated blood.
2 - Vein contains deoxygenated blood.
(iii) RBC

330. The following simplified diagram refers to the

outline plan of the circulation of blood in a
mammal.

(i) Label the parts 1-4.

(ii) How does the structure labelled 4 differ from
artery in its location?
(iii) Name the various layers present in the walls
(i) Study the diagram and write the number of arteries and veins.
and name of the blood vessels in each case as
mentioned above. Ans : COMP 2016

(ii) (a) Several hours after a meal containing a (i) 1. Open valve
lot of protein, which vessel will contain 2. Contracting skeletal muscle squeezing the
the highest concentration of urea? vein
(b) Which vessel would contain the highest 3. Closed valve
concentration of amino acids and glucose 4. Vein
soon after a meal? (ii) Veins are superficial while arteries are deep
seated.
(c) Which vessel begins and ends in
(iii) Tunica externa, tunica media and tunica
capillaries?
interna.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 257

CHAPTER 8
THE EXCRETORY SYSTEM

like structure which store urine temporarily.

SUMMARY
3.1 Structure of the Kidney

1. EXCRETION The structure of the kidney is shown in figure.

The functional unit of the kidney is the nephron
Excretion is the elimination of metabolic wastes or kidney tubule. It is important to know the
from the body. The excretory organs maintain position of the nephrons in relation to the overall
constant internal environment required by the plan of the kidney. The outer cortex of the kidney
body cells by conserving certain substances and contains the Bowman’s capsules and the proximal
by eliminating other metabolic wastes like urea, and distal convoluted tubules, while the medulla
uric acid, sweat, carbon dioxide and bile pigments. houses the loops of Henle and the collecting ducts.
There are four main excretory organs in our body: Bundles of collecting ducts form Pyramids, which
(i) The skin which removes sweat. deliver urine into an open space called the pelvis.
(ii) The lung which removes carbon dioxide and The ureters connect the kidneys to the bladder.
water.
(iii) Liver excretes cholesterol, bile pigments, and 4. NEPHRONS
drugs. Each human kidney possesses about one million of
(iv) The kidneys which remove nitrogenous waste functional and structural units known as nephrons
materials like urea, uric acid, ammonia, which or kidney tubules which has got two main parts.
are produced during protein and nucleic acid (i) Malpighian body (The Bowman’s capsule and
metabolism. Removal of excess water from the glomerulus together are often known as
the body is known as osmoregulation. Kidney the Malpighian body or renal corpuscle).
plays an important role in osmoregulation (ii) Renal tubule.
also. It controls water balance in the body. It The second part, i.e., the renal tubule is divided
also removes excess vitamins, drugs, alcohols into proximal convoluted tubule, loop of Henle
and dyes which are not required by the body. and distal convoluted tubule. Nephrons are
2. NITROGENOUS WASTE PRODUCTS engaged in three basic processes :
1. Filtering blood,
When animals excrete ammonia, they are called 2. Returning useful substances to blood so that
ammonotelic as amphibians and bony fish. When they are not lost from the body, and
the animals excrete urea they are called ureotelic 3. Removing substances from the blood that are
as sharks, alligators, other mammals and man. not needed by the body. As a result of these
Sometimes uric acid is excreted as excretory processes, nephrons maintain the homeostasis
product. And in animals like insects, land reptiles of blood and urine is produced.
and birds it is called uricotelism and these animals
are called uricotelic. 4.1 Parts of Nephron

3. HUMAN EXCRETORY SYSTEM Each nephron consists of two portions : a renal

corpuscle, where plasma is filtered, and a renal
It consists of a pair of kidneys, a pair of ureters, a tubule into which the filtered fluid passes.
urinary bladder and urethra. Each renal corpuscle has two components: the
(i) Urethra : It is a canal which extends from the glomerulus (capillary network) and the glomerular
neck of the bladder and leads to exterior. (Bowman’s) capsule, a double-walled epithelial
(ii) Urinary bladder : A pear-shaped muscular sac- cup that surrounds the glomerulus. From the
CH 8 : THE EXCRETORY SYSTEM

glomerular capsule, fluid filtered from the plasma 5. OSMOREGULATION

passes into the renal tubule, which has three main Kidneys play a role in homeostasis, which is the
sections. In the order that fluid passes through maintenance of constant internal conditions in the
them the renal tubule consists of a (1) proximal body. The kidneys selectively eliminate water and
convoluted tubule. (2) loop of Henle (nephron solutes, such as sodium, potassium and chloride
loop), and (3) distal convoluted tubule. ions, so that the water and solute balance of the
Proximal denotes the portion of the tubule body is kept at the correct level. The need to
attached to the glomerular capsule, and distal balance the solute concentration of body fluids is
denotes the portion that is farther away. called osmotic regulation, or osmoregulation.
Convoluted means the tubule is tightly coiled
rather than straight. The renal cortex, whereas 6. FUNCTIONS OF KIDNEY
the loop of Henle extends into the renal medulla, The kidney (particularly its distal tubules)
makes a hairpin turn, and then returns to the contributes to several vital functions to maintain
renal cortex. homeostatic mechanism, such as:
1. Excretion of nitrogenous waste products.
2. Regulation of water balance.
3. Regulation of acid-base balance.
4. Elimination of other substances.
5. Regulation of blood pressure.
About 1.2 litres of urine is produced from 4-6 litres
of blood in a normal healthy person per day. The
act of urination or micturition is a sort of reflex
action. Urine is a transparent, pale yellow fluid
acidic in nature. It also contains urea, uric acid,
creatinine, sodium chloride, potassium chloride,
ammonia and water. Presence of glucose indicates
the symptoms of diabetes.

7. FORMATION OF URINE
Urine is produced in nephrons in three different stages :
(i) Ultrafiltration,
(ii) Selective reabsorption and
Nephron
(iii) Secretion.
The distal convoluted tubules of several nephrons When kidney is not working properly water
empty into a single collecting duct. accumulates in the body which is known as dropsy.
Excretion is the removal of chemical waste from When urea is not removed from the blood due
the body, waste that is produced by the metabolic to improper functioning of the kidney it is called
processes within cells and which would be toxic Uremia. When both the kidneys are completely
if allowed to accumulate. One should not confuse damaged the nitrogenous waste products are
excretion with egestion or defaecation which is removed by dialysis.
the removal of undigested food and other debris
7.1 Conduction of Urine
from the intestine.
Different fluids are often compared on the The urine is formed continuously in the
basis of their solute concentrations. A solution uriniferous tubules, from where is passes into the
that has a higher solute concentration than ureters through pelvis. The urine moves down
another is said to be hypertonic. A solution that the ureters due to the peristaltic waves in its
has a lower solute concentration than another is walls. At the other end the ureters open into the
hypotonic. A solution that has exactly the same urinary bladder through oblique tunnels. When
solute concentration is isotonic. So, for example, the urinary bladder is sufficiently full of urine,
we can say that sea water is hypertonic to human the free nerve endings in the walls of bladder get
blood plasma, because sea water has a much stimulated which induce an urge to pass out urine.
higher salt concentration. The sphinctor muscle at the neck of the bladder
relaxes and a wave of contraction passes into the
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 259

bladder, thereby draining the urine out through Thus (c) is correct option.
urethra. Due to oblique passage, the ureters get
closed and prevent the back flow of urine into 4. The structure that stores urine temporarily is :
them. The process of passing out urine is called (a) Ureter (b) Urethra
micturition. (c) Urinary bladder (d) Kidneys
Ans : COMP 2021

The urinary bladder is the structure that stores

urine temporarily. It is a hollow, muscular organ
MULTIPLE CHOICE QUESTION that collects urine from the kidneys through the
ureters and stores it until it is expelled from the
body through the urethra during urination.
1. The Loops of Henle lie in
Thus (c) is correct option.
(a) Renal Cortex
(b) Renal Medulla 5. The main nitrogenous waste formed in the human
(c) Renal Pelvis body :
(d) Renal Artery (a) Uric acid (b) Urea
Ans : SQP 2025 (c) Ammonia (d) Creatinine
Thus (b) is correct option. Ans : SQP 2021

Urea is the main nitrogenous waste formed in the

2. A single highly coiled tube where sperms are
human body. It is produced in the liver through
stored, gets concentrated and mature is known
the urea cycle as a result of the breakdown of
as :
proteins and amino acids. The urea is then
(a) Epididymis
transported through the blood to the kidneys,
(b) Vas efferentia
where it is excreted in urine.
(c) Vas deferens
Thus (b) is correct option.
(d) Seminiferous tubule
Ans : MAIN 2015 6. The nephron discharge their urine at the
(a) urinary bladder
The epididymis is a highly coiled tube located
(b) urethra
at the back of the testes where sperms are
(c) renal pyramid
stored, concentrated, and mature. After being
(d) renal pelvis
produced in the seminiferous tubules of the
testes, immature sperms pass into the epididymis, Ans : MAIN 2017
where they undergo further maturation, gaining The renal pelvis is the part of the kidney where
motility and the ability to fertilize an egg. urine from the nephrons is collected. After
This process prepares the sperm for their journey the filtration process, the urine flows from the
through the vas deferens during ejaculation. collecting ducts of the nephrons into the renal
Thus (a) is correct option. pelvis, which then channels the urine into the
ureters, eventually leading to the urinary bladder.
3. The nephrons discharge their urine at the :
Thus (d) is correct option.
(a) Urinary bladder
(b) Urethra 7. The chief nitrogenous waste in mammals is
(c) Renal pelvis (a) ammonia (b) uric acid
(d) Renal pyramid (c) urea (d) amino acids
Ans : SQP 2016
Ans : COMP 2015
The renal pelvis is the funnel-shaped structure In mammals, the chief nitrogenous waste product
in the kidney where urine from the nephrons is urea. It is produced in the liver from the
is collected after being filtered. The urine from breakdown of proteins and amino acids through
the collecting ducts of the nephrons flows into the urea cycle. Urea is less toxic compared to
the renal pelvis, which then leads to the ureter, ammonia and is efficiently excreted by the kidneys
carrying the urine to the urinary bladder for in urine.
storage. Thus (c) is correct option.
CH 8 : THE EXCRETORY SYSTEM

Identify the correct pair of hormones: Calcitonin is produced by the thyroid gland and
(a) P – Prolactin, Q – Thyroxine. helps decrease blood calcium levels by inhibiting
(b) P – Oxytocin, Q – Cortisol. osteoclast activity in bones.
(c) P – Estrogen, Q – Insulin. Thus (b) is correct option.
(d) P – Testosterone, Q – Thyroxine.
41. Neha attempted to match the hormones with
Ans : SQP 2018
their specific actions.
Prolactin is responsible for stimulating milk
production in the breasts, particularly during Hormone Action
and after pregnancy. Thyroxine, produced by the P Stimulates the production of
thyroid gland, increases the metabolic rate and testosterone
energy expenditure in the body. Q Increases water reabsorption in the
Thus (a) is correct option. kidneys
39. Sita attempted to match the hormones with their Identify the correct pair of hormones:
effects on the human body. (a) P – Follicle-Stimulating Hormone, Q –
Vasopressin.
Hormone Effect on the Body (b) P – Testosterone, Q – Aldosterone.
P Regulates blood sugar levels (c) P – Luteinizing Hormone, Q – Vasopressin.
(d) P – Estrogen, Q – Cortisol.
Q Promotes the body’s response to
stress Ans : SQP 2006

Identify the correct pair of hormones: Luteinizing Hormone (LH) stimulates the
(a) P – Insulin, Q – Glucagon. production of testosterone in males by acting on
(b) P – Glucagon, Q – Adrenaline. the Leydig cells in the testes. Vasopressin (also
(c) P – Cortisol, Q – Insulin. known as antidiuretic hormone, ADH) increases
(d) P – Adrenaline, Q – Thyroxine. water reabsorption in the kidneys by promoting
the insertion of aquaporins in the renal tubules,
Ans : MAIN 2014
thus concentrating the urine and conserving
Glucagon is a hormone produced by the pancreas water.
that raises blood sugar levels by promoting Thus (c) is correct option.
the conversion of stored glycogen into glucose.
Adrenaline (also known as epinephrine) is
produced by the adrenal glands and prepares the DIRECTION : Conversation Type Question
body for a 'fight or flight' response, increasing
heart rate and energy availability. 42. A biology teacher asked her students to identify
Thus (b) is correct option. two examples of homologous structures in the
human body.
40. Vikram tried to match hormones with their roles Raj said:Forelimbs of humans and whales.
in the human body. Sonu said: Wings of a bat and feathers of a bird.
Lata said: Tailbone and wisdom teeth.
Hormone Role in the Body Abhay said: Pinna and Ossicles.
P Triggers ovulation Who were correct?
Q Decreases blood calcium levels (a) Raj and Lata
(b) Sonu and Abhay
Identify the correct pair of hormones: (c) Raj and Sonu
(a) P – Progesterone, Q – Calcitonin. (d) Lata and Abhay
(b) P – Luteinizing Hormone, Q – Parathyroid
Hormone. Ans : MAIN 2002

(c) P – Estrogen, Q – Calcitonin. Raj and Sonu correctly identified homologous

(d) P – Follicle-Stimulating Hormone, Q – Insulin. structures, as forelimbs of humans and whales
Ans : COMP 2010
share a common ancestry, and wings of bats and
birds have similar underlying bone structures.
Luteinizing Hormone (LH) triggers ovulation by Thus (c) is correct option.
stimulating the release of the egg from the ovary.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 261

15. Maximum amount of water from the glomerular 19. The fluid that is collected in the Bowman’s
filtrate is reabsorbed in capsule is
(a) DCT (a) urine
(b) PCT (b) a solution of wastes
(c) ascending limb of Henle’s loop (c) a solution that contains the excretory wastes
(d) descending limb of Henle’s loop ready for excretion
(d) glomerular filtrate
Ans : SQP 2020

The proximal convoluted tubule (PCT) is Ans : SQP 2018

responsible for reabsorbing the maximum amount The fluid that collects in Bowman's capsule is
of water, along with essential nutrients such as known as glomerular filtrate. This filtrate contains
glucose and ions, from the glomerular filtrate. water, ions, glucose, amino acids, and small waste
Around 65-70% of the filtrate is reabsorbed in molecules, but no large proteins or blood cells, as
this section of the nephron. they are too large to pass through the filtration
Thus (b) is correct option. barrier.
Thus (d) is correct option.
16. Glomerular filtrate does not contain
(a) glucose (b) amino acids 20. Glomerular filtrate contains
(c) hormones (d) proteins (a) blood with proteins but without cells
(b) plasma without sugars
Ans : MAIN 2023
(c) blood without urea
Glomerular filtrate does not contain large molecules (d) blood plasma without blood cells and proteins
like proteins because they are too large to pass
through the filtration membrane of the glomerulus. Ans : MAIN 2010

The filtrate typically contains water, glucose, Glomerular filtrate is essentially blood plasma
amino acids, ions, and small waste molecules. without blood cells and proteins. The filtration
Thus (d) is correct option. process at the glomerulus allows water, ions,
glucose, amino acids, and small waste molecules
17. More ADH means to pass through, but large molecules like proteins
(a) less permeable DCT and blood cells are too large to be filtered.
(b) dilute urine Thus (d) is correct option.
(c) concentrated urine
(d) fall in blood osmotic pressure 21. The nephrons discharge their urine at
(a) urinary bladder (b) urethra
Ans : COMP 2021
(c) renal pyramid (d) renal pelvis
More ADH (antidiuretic hormone) increases
the permeability of the distal convoluted tubule Ans : COMP 2006

(DCT) and the collecting ducts to water, allowing The nephrons discharge urine into the renal
more water to be reabsorbed back into the pelvis, which is a funnel-shaped structure in the
bloodstream. This results in concentrated urine kidney that collects the urine from the nephrons.
and reduced water loss from the body. From the renal pelvis, urine then flows into the
Thus (c) is correct option. ureter and is transported to the urinary bladder
for storage.
18. Diabetes insipidus is caused by the deficiency of Thus (d) is correct option.
hormone
(a) ADH (b) insulin 22. ‘Aquatic animals excrete ammonia’. Which one
(c) glucagon (d) oxytocin of the following statements does not support this
statement?
Ans : MAIN 2020
(a) Ammonia is released from the body in gaseous
Diabetes insipidus is caused by a deficiency of state
ADH (antidiuretic hormone), also known as (b) Ammonia is easily soluble in water
vasopressin. ADH regulates water reabsorption in (c) Ammonia is highly toxic and needs to be
the kidneys, and its deficiency leads to excessive eliminated when formed
urine production and thirst. (d) Ammonia gets converted into less toxic form
Thus (a) is correct option. called urea and uric acid
CH 8 : THE EXCRETORY SYSTEM

8. Glomerulus receives the blood through Ans : SQP 2000

(a) efferent arteriole (b) afferent arteriole The proximal convoluted tubule (PCT) is
(c) vasa rectae (d) renal vein where all the glucose and most of the water are
Ans : MAIN 2010
reabsorbed from the glomerular filtrate back
into the bloodstream. This process ensures that
The afferent arteriole carries blood to the essential nutrients and water are retained by the
glomerulus, a network of capillaries involved body while waste products continue through the
in the filtration of blood in the nephron. After nephron for excretion.
filtration, the filtered blood leaves the glomerulus Thus (b) is correct option.
through the efferent arteriole.
Thus (b) is correct option. 12. The net pressure gradient that causes fluid to
filter our of the glomeruli into the capsule is
9. Maximum amount of water from the glomerular (a) 75 mm Hg
filtrate is absorbed in. (b) 20 mm Hg
(a) descending limbs of loop of Henle (c) 30 mm Hg
(b) ascending limb of loop of Henle (d) 50 mm Hg
(c) proximal convoluted tubule
(d) distal convoluted tubule Ans : COMP 2017

Ans : SQP 2008 The net filtration pressure that drives the filtration
of fluid from the glomeruli into Bowman's capsule
The proximal convoluted tubule (PCT) is is approximately 20 mm Hg. This pressure results
responsible for absorbing the maximum amount of from the balance of hydrostatic pressure in the
water, along with essential nutrients like glucose, glomerular capillaries, oncotic pressure, and the
amino acids, and ions, from the glomerular pressure in Bowman's capsule.
filtrate. Approximately 65-70% of the water and Thus (b) is correct option.
solutes are reabsorbed in this part of the nephron.
Thus (c) is correct option. 13. On a cool and wet day, people urinate more because of
(a) the kidney is more active on a wet day
10. Excretion process involves
(b) the uriniferous tubule no longer absorbs water
(a) removal of nitrogenous waste
(b) removal of bile pigments (c) reduced rate of sweating
(c) removal of byproducts of anabolism and (d) all of these
catabolism Ans : MAIN 2012
(d) All of the above
On a cool and wet day, people tend to urinate
Ans : MAIN 2002 more because the reduced rate of sweating means
Excretion is a process that helps the body remove less water is lost through the skin. As a result,
waste products. It includes the elimination the kidneys excrete more water through urine to
of nitrogenous waste like urea, uric acid, and maintain the body's fluid balance.
ammonia, which come from protein metabolism. Thus (c) is correct option.
The excretory system also removes bile pigments
produced from the breakdown of hemoglobin, 14. The thin membranous sac serving as the reservoir
which are eliminated in feces. Additionally, of urine is
byproducts of anabolism and catabolism are (a) ureter
removed, keeping the body's internal environment (b) urinary bladder
balanced. (c) glomerulus
Thus (d) is correct option. (d) kidney
Ans : COMP 2016
11. Reabsorption of all the glucose and most of the
water occurs in The urinary bladder is a thin membranous sac
(a) distal convoluted tubule that serves as the reservoir for urine. It stores
(b) proximal convoluted tubule urine until it is ready to be expelled from the
(c) Loop of Henle body through the urethra.
(d) collecting duct Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 263

32. Which substance is present at a lower concentration (a) increased ADH secretion
in the renal artery than in the renal vein ? (b) increased rate of ultra-filtration
(a) Amino acids (b) Glucose (c) increased sodium level
(c) Carbon dioxide (d) Urea (d) reduced rate of absorption from filtrate
Ans : MAIN 2000 Ans : COMP 2018

The renal vein carries blood away from the When the rate of reabsorption from the filtrate
kidneys after waste products like urea have been is reduced, less water is reabsorbed back into the
filtered, and it contains more carbon dioxide due body, leading to the production of excessive dilute
to metabolic processes in the kidney. The renal urine.
artery, supplying oxygenated blood, has a lower Thus (a) is correct option.
concentration of carbon dioxide.
Thus (c) is correct option. 36. In a lab session, students examine a nephron's
structure. The instructor discusses the locations of
33. Which of the following statement(s) is/are true? its various parts, prompting a question about the
(a) Urine is hypertonic in distal convoluted proximal convoluted tubule Proximal convoluted
tubule tubule of nephron lies in
(b) When the urine passes into collecting tubule, (a) medulla (b) cortex
it becomes hypotonic (c) ureter (d) None of the above
(c) Urine becomes more and more hypotonic as it Ans : COMP 2010
passes through Henle’s loop
(d) Both (a) and (c) It is located in the renal cortex, where it is
involved in the reabsorption of water, ions, and
Ans : COMP 2005 nutrients from the filtrate.
As urine passes through the descending limb of Thus (b) is correct option.
Henle's loop, water is reabsorbed, and it becomes
37. During a practical session, students are studying
more concentrated (hypertonic). However, in
the anatomy of the nephron. The instructor
the ascending limb, salts are actively reabsorbed
explains the different segments of the nephron
without water, making the urine more hypotonic.
and their locations within the kidney, leading to
Thus (d) is correct option.
a question about where the proximal convoluted
34. A patient is undergoing a kidney function test. tubule is found. The proximal convoluted tubule
The doctor mentions that the liquid collected in of a nephron is present in
the Bowman’s capsule plays a key role in filtration. (a) cortex (b) medulla
Liquid which collects in Bowman’s capsule is (c) ureter (d) None of these
(a) water and sulphates Ans : MAIN 2004
(b) water and glycogen
The proximal convoluted tubule is located in the
(c) concentrated urine
cortex of the kidney, where it plays a role in the
(d) plasma minus blood proteins reabsorption of water, ions, and nutrients from
Ans : MAIN 2009 the filtrate.
Thus (a) is correct option.
The liquid that collects in Bowman's capsule is
essentially plasma minus blood proteins. It is a
filtrate that includes water, ions, glucose, amino DIRECTION : Matching type question :
acids, and other small molecules, but large
molecules like blood proteins and cells are not 38. Raj tried to match the hormones with their
filtered through the glomerulus due to their size. respective functions in the human body.
Thus (d) is correct option.
Hormone Function
35. In a physiology class, Dr. Rao explains how P Stimulates milk production in
hormones and physiological processes affect urine breasts
concentration and volume. A student questions
the causes of excessive dilute urination. Excessive Q Increases metabolic rate and energy
dilute urination is because of expenditure
CH 8 : THE EXCRETORY SYSTEM

87. Arrange the terms in correct sequence Glomerulus, DIRECTION : Give the biological/technical term for
renal vein, efferent arterioles, renal artery, afferent the following :
arterioles, secondary capillaries.
Ans : SQP 2018
94. Pigment providing colour to urine.

Renal artery, afferent arterioles, glomerulus, Ans : COMP 2016

efferent arterioles, secondary capillaries, renal Urochrome

vein.
95. The removal of nitrogenous wastes from the body.
88. Which substances are reabsorbed in distal
Ans : MAIN 2016
convoluted tubules ?
Excretion
Ans : MAIN 2021

Water and sodium.

DIRECTION : Correct the following statement by
89. State whether the following statements are True changing the underlined word :
or False. If False rewrite the correct form of the
statement by changing the first or last word only : 96. Normal pale yellow colour of the urine is due to
Urethra carries urine from kidney to the urinary the presence of the pigment Melanin.
bladder. Ans : COMP 2018
Ans : COMP 2023 Urochrome
Ureter carries urine from kidney to the urinary
bladder. DIRECTION : State the exact location :
90. What is the total quantity of glomerular filtrate
produced by us per day and what does it contain? 97. Proximal convoluted tubule.

Ans : SQP 2011

Ans : SQP 2016

16 litres of glomerular filtrate we produce per day. Near the Bowman’s capsule in the cortex of
It contains Na+, K+, Ca++, Cl– hormones, urea, kidney.
salts in ionic stage, uric acids, glucose, water,
amino acids, vitamins. DIRECTION : Complete the following :
91. What is the purpose of tubular secretion?
98. The U-shaped portion of the nephron is______.
Ans : MAIN 2022
Ans : MAIN 2010
The harmful substances, that are not filtered at
Loop of Henle
the glomerulus are discharged into the urine by
tubular secretion. 99. Most of the glucose is absorbed in______part
of nephron.
92. How much urine is secreted by human per day?
Ans : SQP 2004
Ans : COMP 2017
proximal convoluted tubule
1.2 litres per day.
100. The organ where urea is produced is______.
93. When does urine become hypotonic and
hypertonic? Ans : COMP 2019

Ans : SQP 2002 liver

When water intake is high, urine secreted is 101. ______hormone increases the reabsorption of
hypotonic to get rid of excess water from the water from the kidney tubule.
body. When body has less amount of water,
body reabsorbs water and urine then it becomes Ans : SQP 2009

hypertonic. ADH
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 265

43. A teacher asked her students to name two 46. A biology teacher asked her students to provide
examples of endocrine glands in the human body. two examples of behavioral adaptations in
Raj said: Pancreas and Thyroid. animals. Raj said: Hibernation and Migration.
Sonu said: Salivary glands and Sweat glands. Sonu said: Camouflage and Mimicry. Lata said:
Lata said: Adrenal gland and Pituitary gland. Web spinning in spiders and Nest building. Abhay
Abhay said: Gall bladder and Kidney. said: Pinna and Ossicles. Who were correct?
Who were correct? (a) Raj and Lata
(a) Raj and Lata (b) Sonu and Abhay
(b) Sonu and Abhay (c) Raj and Sonu
(c) Lata and Abhay (d) Lata and Abhay
(d) Raj and Sonu
Ans : COMP 2005
Ans : COMP 2017
Raj and Sonu correctly identified behavioral
Raj and Lata correctly named endocrine glands. adaptations; hibernation and migration are
The pancreas and thyroid are endocrine glands that behaviors that help animals survive environmental
secrete hormones directly into the bloodstream. changes.
Thus (c) is correct option. Thus (c) is correct option.

44. A biology teacher asked her students to give two

examples of inherited traits in humans.
Raj said: Eye color and height.
Sonu said: Skills and hobbies.
ONE MARK QUESTIONS
Lata said: Blood type and hair color.
Abhay said: Pinna and Ossicles.
Who were correct? DIRECTION : Name the following
(a) Raj and Lata
(b) Sonu and Abhay 47. The main nitrogenous waste in man.
(c) Raj and Abhay
Ans : SQP 2023
(d) Lata and Sonu
urea
Ans : SQP 2013

Raj and Lata provided examples of inherited 48. Structural and functional unit of the kidney.
traits, as eye color and blood type are determined Ans : MAIN 2011
by genetics.
Nephron
Thus (a) is correct option.
49. An organ that produces urea.
45. A teacher asked her students to list two
adaptations in animals for desert survival. Ans : COMP 2016
Raj said: Cactus and Camels. Liver
Sonu said: Polar bear and penguin.
Lata said: Kangaroo and Fennec fox. 50. Knot like mass of blood capillaries inside the
Abhay said: Pinna and Ossicles. Bowman’s capsule.
Who were correct?
Ans : SQP 2013
(a) Raj and Sonu
(b) Lata and Abhay Glomerulus
(c) Raj and Lata
51. The organ which produces urea.
(d) Abhay and Sonu
Ans : COMP 2017
Ans : MAIN 2009
Liver
Raj and Lata correctly identified adaptations for
desert survival, as camels have features to retain 52. The outer region of the kidney.
water and fennec foxes have large ears to dissipate
heat. Ans : MAIN 2018

Thus (c) is correct option. cortex

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CH 8 : THE EXCRETORY SYSTEM
Ans : SQP 2002
27. Ultrafiltrate generated by the glomerulus is having
This is because aquatic animals typically excrete all the constituents of the blood plasma except
ammonia directly, and the conversion of ammonia (a) protein (b) WBC
into urea or uric acid is characteristic of terrestrial (c) RBC (d) All of these
animals like mammals and birds, not aquatic Ans : MAIN 2023
animals. Ultrafiltrate generated by the glomerulus contains
Thus (a) is correct option. all the constituents of blood plasma except
23. Which one of the following is NOT an excretory proteins, white blood cells (WBCs), and red blood
activity ? cells (RBCs), as these larger components are not
(a) Passing out faecal matter filtered through the glomerular membrane.
(b) Sweating Thus (c) is correct option.
(c) Removal of urea. 28. The formation of urine in our excretory system is
(d) giving out carbon dioxide known as
Ans : MAIN 2019 (a) uropoiesis (b) haemopoiesis
(c) leucopoiesis (d) None of these
This is because the passing of faecal matter is
a part of the digestive process (egestion), not Ans : SQP 2003
excretion, which involves the removal of metabolic Uropoiesis refers to the process of urine formation
waste products like urea, carbon dioxide, and in the kidneys.
sweat from the body. Thus (a) is correct option.
Thus (d) is correct option.
29. Excretion primarily involves
24. The principal nitrogenous waste in man is (a) removal of all byproducts during anabolism
(a) urea (b) uric acid (b) removal of byproducts during anabolism
(c) ammonia (d) nitrogen (c) throwing out excess water
Ans : COMP 2022 (d) removal of nitrogenous wastes
Humans primarily excrete urea as the main Ans : MAIN 2021
nitrogenous waste, which is produced in the liver Excretion is the biological process by which
through the urea cycle. organisms remove waste products, particularly
Thus (a) is correct option. nitrogenous wastes such as urea, uric acid, and
25. The human, urea is formed in the ammonia, that are produced during metabolism
(a) uretar (b) spleen Thus (d) is correct option.
(c) liver (d) kidney 30. Haemodialysis is associated with
Ans : COMP 2020 (a) liver (b) spleen
(c) stomach (d) kidney
The liver is responsible for converting ammonia,
a toxic byproduct of protein metabolism, into Ans : COMP 2017
urea through the urea cycle. This urea is then Haemodialysis is a medical procedure used to filter
transported to the kidneys for excretion. waste products and excess fluids from the blood
Thus (c) is correct option. when the kidneys are not functioning properly
26. Glomerulus is present in Thus (d) is correct option.
(a) renal medulla 31. Ammonia is converted into urea in
(b) renal cortex (a) kidney (b) liver
(c) renal pelvis (c) ureters (d) stomach
(d) renal pyramid
Ans : SQP 2004
Ans : SQP 2019
This conversion occurs through the urea cycle,
The glomerulus, a network of capillaries where which detoxifies ammonia produced during
blood filtration begins, is located in the renal protein metabolism. The urea is then transported
cortex of the kidney. to the kidneys for excretion.
Thus (b) is correct option. Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 267

73. Persons suffering from very low blood pressure Ans : MAIN 2010

pass no urine. Why ? Normal human urine contains the following

Ans : MAIN 2010
inorganic and organic substances in water:

Ultrafiltration does not take place in persons

having low blood pressure. So they do not pass
urine due to acute renal failure.

74. What is dialysis ?

Ans : SQP 2009

The process of separating large solute molecules

from the small ones by semi-permeable membrane
is called dialysis.
81. What is artificial kidney ?
75. State why the people with single damaged kidney
Ans : SQP 2001
need not undergo dialysis.
It is a dialysis machine which filters waste
Ans : COMP 2016
products from the blood like urea, uric acid which
One kidney is sufficient to filter out the excretory are poisonous and are not removed along with
products. Dialysis is carried out only in case of urine due to renal failure.
failure of both the kidneys.
82. Name two blood vessels which enter and leave
76. Name the structure of the kidney where glomerulus kidney.
is enclosed. Ans : MAIN 2005
Ans : MAIN 2020
Renal artery enters the kidney carrying oxygenated
Bowman’s capsule. blood and urea, uric acid and creatinine, while
renal veins leave the kidneys and carry de-
77. How is blood brought to Bowman’s capsule ? oxygenated blood without urea and uric acids
Ans : SQP 2022 which were deposited in the kidneys.
Renal artery carries oxygenated blood along with 83. Why is right kidney slightly lower in position
nitrogenous waste material to the Bowman’s compared to the left kidney ?
capsule.
Ans : COMP 2003

78. “Urine is formed from alkaline blood but it is To adjust liver in the right side of the abdominal
acidic in nature”. Explain the significance of the cavity.
above statement.
84. Name the duct which transports urine from the
Ans : COMP 2023
kidney to the urinary bladder.
Though blood is alkaline in nature with pH 7.3-
Ans : SQP 2007
7.45 but urine is acidic because many acidic
products are continuously added to blood, which Ureter.
the kidney removes by selectively filtering the
85. Name the organ in man concerned with
acidic substances from the blood into the urine.
maintaining water balance in the body.
79. What is dropsy ? Ans : MAIN 2004

Ans : SQP 2017 Kidney.

It is a condition in the body when improper 86. What is hilus ?
functioning of kidney leads to accumulation of
water. Ans : COMP 2009

The depression present on the concave surface of

80. Write the composition of urine of a man.
the kidney is called hilus.
CH 8 : THE EXCRETORY SYSTEM

53. The hormone that helps to increase the Ans : COMP 2014

reabsorption of water from the kidney. Sphincter muscle

Ans : MAIN 2020
64. The process by which kidneys regulate the water
ADH/Vasopressin. content of the body.

54. The process by which metabolic wastes are Ans : SQP 2015

removed from the body. Osmoregulation

Ans : COMP 2015
65. The excretory products formed by liver.
Excretion
Ans : MAIN 2022

55. A tuft of blood capillaries found in the Bowman’s Urea, bile (contain pigments)
capsule of nephron.
66. The branch of renal artery which enters into the
Ans : SQP 2001
Bowman’s capsule.
Glomerulus
Ans : COMP 2004

56. The structure that brings urine from the kidney Afferent arteriole.
to the urinary bladder.
67. Name any two organic constituents of normal
Ans : SQP 2019
urine.
Ureter
Ans : SQP 2000

57. Main excretory organ in man. Urea, creatinine.

Ans : MAIN 2013
68. The blood vessels supplying blood to the kidney.
Kidney
Ans : MAIN 2004

58. The substance found in excess in the urine of a Renal artery

diabetic person.
69. The outer part of the kidney containing the
Ans : COMP 2014
Bowman’s capsules.
Glucose
Ans : SQP 2009

59. The blood vessel leaving the kidney. Cortex

Ans : SQP 2017
70. The form in which glucose is stored in liver.
Renal vein
Ans : COMP 2007

60. The term used for Bowman’s capsule and Glycogen

glomerulus together.
Ans : MAIN 2008 DIRECTION : Answer the following questions :
Malpighian capsule
71. Expand the abbreviation - ADH. Give one
61. The thin membranous sac serving as the reservoir example of a diuretic substance.
of urine.
Ans : SQP 2025
Ans : MAIN 2004
Antidiuretic Hormone
Urinary bladder Alcohol, Coconut water, Caffeine, etc.

62. An organic waste produced by the lungs in man. 72. Name two substances found both in urine and
Ans : SQP 2020
sweat.

Carbon dioxide. Ans : SQP 2007

Uric acid and water

63. The muscle which guards the urethra.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 269

102. The tube that passes urine out of the body Ans : COMP 2017

is______. Bile, rest are excretory products of humans.

Ans : MAIN 2005

urethra DIRECTION : Differentiate between the following

pairs on the basis of what is mentioned in brackets:
103. Blood leaves Bowman’s capsule by______.
Ans : SQP 2020
112. State the difference between Micturition and
Parturition.
Efferent arteriole
Ans : SQP 2025
104. The human kidney is made up of______. Micturition: It is the expulsion of urine from the
Ans : SQP 2011 urinary bladder.
Parturition: It the expulsion of the fully developed
nephrons
foetus from the uterus at the end of gestation.
105. The inner part of kidney is called______.
113. Differentiate between Afferent arteriole and
Ans : MAIN 2023 Efferent arteriole (diameter).
medulla Ans : MAIN 2024

106. Ureter is the connecting link between______ Afferent arteriole : It has a larger diameter that
and______. carries blood from renal artery to the glomerulus.
Ans : SQP 2002 Efferent arteriole : It has a smaller diameter that
carries blood from the glomerulus and into the
kidney, urinary bladder renal vein.
107. The sum total of all the chemical reactions taking 114. Renal cortex and Renal medulla (Parts of the
place in the cell is called______. nephrons present)
Ans : COMP 2007
Ans : MAIN 2017
metabolism Renal cortex : Bowman’s capsule, PCT and DCT
108. The funnel-shaped structure of kidney is Renal medulla : Loop of Henle
called______. 115. Bowman’s capsule and Malpighian capsule. (parts
Ans : SQP 2000 included) (Excretory System)
pelvis Ans : SQP 2013

109. Automatic self-regulation of salt and water within Bowman’s capsule : Include glomerulus
the body is called______. Malphigian capsule : Include glomerulus and
Bowman’s capsule
Ans : MAIN 2017
116. Ureter and Urethra [function]
homeostasis
Ans : MAIN 2018
110. Knot of blood vessel inside the Bowman’s capsule
is______. Ureter : Removes urine from kidney to bladder
Urethra : Passes urine out of the body
Ans : MAIN 2013

Glomorulus.
DIRECTION : State whether the following are True
or False:
DIRECTION : Choose the ODD one out of the
following terms given and name the CATEGORY to 117. Protein diet makes urine acidic.
which the others belong :
Ans : SQP 2020

111. Bile, Urea, Uric acid, Ammonia True.

CH 8 : THE EXCRETORY SYSTEM

118. Nitrogenous wastes are formed by the breakdown Ans : COMP 2017

of fat. It collects filtered and deoxygenated blood.

Ans : MAIN 2013
128. Henle’s loop
False. Nitrogenous wastes are formed by the
Ans : SQP 2007
breakdown of protein.
It helps in the reabsorption of water and sodium
119. Ureters bring urine from urinary bladder to ions.
outside the body.
129. Ureter
Ans : SQP 2014
Ans : MAIN 2010
False. Urethra bring urine from urinary bladder
to outside the body. It transports urine from kidney to the urinary
bladder.
120. Renal artery carries blood to the kidney.
130. Urethra
Ans : MAIN 2023
Ans : SQP 2004
True.
To transport urine from urinary bladder to the
121. Afferent arteriole is narrower than efferent exterior.
arteriole.
131. Kidney
Ans : COMP 2005
Ans : SQP 2002
False. Afferent arteriole is broader than efferent
arteriole. Formation of urine and osmoregulation.

122. Glomerulus helps in reabsorption.

DIRECTION : In the following case, pick out one
Ans : SQP 2003 term which includes all the three:
False. Glomerulus helps in ultrafiltration.
132. Glomerular filtrate, Bowman’s capsule,
123. Glomerular filtrate contains glucose. Ultrafiltration, Glomerulus.
Ans : MAIN 2007 Ans : COMP 2001

True. Ultrafiltration

124. Urea is formed in the kidney.

DIRECTION : Given below is a set of five terms.
Ans : COMP 2009
Rewrite the terms in the correct order so as to be
False. Urea is formed in the liver. in logical sequence, One has been done for you. e.g.,
Arterioles, vein, artery, capillaries, vennule Ans. -
125. Renal vein contains less urea. Artery $ arterioles $ capillaries $ vennules
Ans : SQP 2021 $ vein
True.
133. Afferent arteriole, renal vein, capillary network,
126. Urethra carries urine from kidney to the urinary glomerulus, efferent arteriole
bladder. Ans : MAIN 2012

Ans : MAIN 2019 Afferent arteriole $ glomerulus $ efferent

False. Ureter carries urine from kidney to the arteriole $ capillary network $ renal vein.
urinary bladder.
DIRECTION : Give reasons for the following:
DIRECTION : State the role of the following:
134. As a result of ultrafiltration alongwith excretory
127. Renal vein products certain useful products like glucose, salt,
etc. are also filtered but these are not excreted.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 271
Ans : SQP 2000
Ultrafiltration is a process of filtration of blood
Glucose, salt, etc. in the glomerular filtrate are in the glomerulus during which the liquid part
reabsorbed in the proximal part of renal tubules. of the blood such as urea, glucose, amino acids
and other substances enter the renal tubule and
135. Glucose is absent in the urine of a healthy person. large molecules remains in the glomerulus which
Ans : COMP 2019 are caned away by efferent arteriole.
Glucose is reabsorbed into the blood stream in 140. Draw a neat diagram of a longitudinal section of a
the proximal part of the nephron. So, a normal human kidney and label Renal Cortex and Renal
healthy person’s urine is devoid of glucose. Medulla on the diagram.
136. There is frequent urination in winter than in Ans : MAIN 2021

summer.
Ans : SQP 2023

In winter, sweating is less, so more water is given

out in the form of urine. Reverse process happens
in summer

137. All living things must excrete.

Ans : MAIN 2020

Metabolic activities of all living things produce

nitrogenous waste materials. These waste
materials, if accumulated in the body, become
poisonous and destroy the vital organs. So,
excretion is a must.

141. State the difference between the following on the

basis of what is given in the brackets.
TWO MARKS QUESTIONS (a) Urea and urine (place of occurrence)
(b) Bowman’s capsule and malpighian capsule
(parts included)
138. Draw a neat, labelled diagram of a Malpighian
Capsule. Ans : MAIN 2013

Ans : SQP 2025 (a) Urea is formed in liver.

Urine is formed in kidney.
Diagram of Malpighian capsule
(b) Bowman’s capsule contains glomerular filtrate.
Malpighain capsule – Contains Bowman’s
capsule and glomerulus.

DIRECTION : Distinguish between the following

pairs:

142. Ureter and Urethra

Ans : SQP 2017

Ureter Urethra
(a) It transports (a) It transports
urine from urine from
139. Define the term Ultrafiltration. kidney to urinary urinary bladder
bladder to the exterior
Ans : MAIN 2024
(exercts out).
CH 8 : THE EXCRETORY SYSTEM

4 – Bowman’s capsule 160.

(ii) The diameter of afferent arteriole is wider and
efferent arteriole is narrower. So, hydrostatic
pressure is high in the glomerulus.
(iii) Renal vein
(iv) 1. Ultrafiltration
2. Selective reabsorption
(v) Henle’s loop and collecting duct

159. The following diagram represents a mammalian

kidney tubule (nephron) and its blood supply.
Parts indicated by the guidelines 1 to 8 are as
follows :

The above diagram is longitudinal section of the

kidneys of mammals and associated structures.
(i) Name the parts indicated by guidelines.
(ii) Which parts in the above diagram :
1. Produce urine.
2. Store urine.
3. Carry urine to the urinary bladder.
(iii) Name the blood vessel that carries urea from
the liver to the urinary bladder.
(iv) Give three differences between the composition
of blood in renal artery and renal vein.
(v) Name the substance formed in excess in the
1. U-shaped loop of Henle urine of a diabetic patient.
2. Proximal convoluted tubule with blood
capillaries. Ans : COMP 2021

3. Bowman’s capsule.
4. Afferent arteriole from renal artery. (i) 1. Aorta 2. Venacava
5. Glomerulus. 3. Renal artery 4. Renal vein
6. Venule to renal vein.
5. Cortex 6. Medulla
7. Collecting tubule.
8. Distal convoluted tubule with blood 7. Pelvis 8. Left ureter
capillaries. 9. Right kidney 10. Urinary bladder
Study the diagram and answer the following
questions in each case: 11. Opening of 12. Sphincter
(i) Where does ultra-filtration take place ? ureter muscle
(ii) Which structure does contain the lowest 13. Urethra.
concentration of urea ? (ii) 1. Kidney.
(iii) Which structure does contain the highest 2. Urinary bladder.
concentration of urea ? 3. Ureter.
(iv) Which structure does normally contain the (iii) Renal artery.
lowest concentration of glucose ? (iv) The impure blood of renal artery contains,
Ans : SQP 2023 (a) oxygen (b) urea (c) uric acid. The pure
blood of renal vein contains CO2 in addition
(i) Glomerulus.
to other constituents of blood. The urea, uric
(ii) Bowman’s capsule.
acid and other nitrogenous substances are
(iii) Collecting tubule.
filtered in the kidney, so renal vein does not
(iv) Collecting tubule.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 273

and the substances present in it.

Ans : COMP 2019

(i) 1- Kidney; 2 - Dorsal aorta; 3 - Ureter; 4 -

Urinary bladder; 5 - Urethra; 6 - Vena cava;
7 - Renal vein.
(ii) Adrenal gland on top of each kidney.
(iii) Urine. The substances present in urine are
water, urea, sodium chloride, etc.

DIRECTION : Complete the following paragraph by

filling in the blanks (i) to (v) with appropriate words :

153. The amount of urine output is under the regulation

of a hormone called
(i) ______secreted by the (ii) ______ lobe
of the pituitary gland. If this hormone secretion
is reduced, there is an increased production of
151. Mention the functions of the different parts of a urine. This disorder is called (iii) ______.
nephron. Sometimes excess glucose is passed with urine due
Ans : SQP 2017
to hyposecretion of another hormone called (iv)
______leading to the cause of a disease called
(i) Renal capsule – ultrafiltration (v) ______.
(ii) Proximal convoluted tubule – reabsorption of
water, glucose, sodium and potassium ions. Ans : MAIN 2016

(iii) Loop of Henle – reabsorption of water and (i) Antidiuretic/Vasopressin Hormone

sodium ions. (ii) Posterior
(iv) Distal convoluted tubule – reabsorption of (iii) Diabetes insipidus/Diuresis
remaining chloride ions and tubular secretion. (iv) Insulin
(v) Collecting duct – pours urine into the pelvis. (v) Diabetes mellitus

152. The given figure shows certain organs and

associated parts in a mammalian body:
FIVE MARKS QUESTIONS

154. Study the diagram given below and then answer

the questions that follow :

(i) Name the parts 1 to 7.

(ii) Which endocrine gland could have been
added in the figure and where? (i) Name the region in the kidney where the
(iii) Name the fluid flowing down through part 3 above structure is present.
CH 8 : THE EXCRETORY SYSTEM

(b) Sphincter muscle (b) It is guarded by (b) It is produced in (b) It is formed in

is absent sphincter muscle. the liver. the kidney.

143. Afferent Arteriole and Efferent Arteriole

Ans : MAIN 2022
THREE MARKS QUESTIONS
Afferent Efferent Arteriole
Arteriole
147. Mention the three major steps involved in the
(a) It carries blood (a) It carries blood production of urine.
containing waste having no waste
materials. material or less Ans : SQP 2021

waste material. (1) Ultrafiltration

(b) It transports (b) It transports (2) Selective reabsorption
blood to the blood away from (3) Tubular secretion
glomerulus. glomerulus.
148. Give reasons :
(i) Urine is thicker in summer than in winter.
144. Excretion and Egestion (ii) Glucose is normally not found in urine.
Ans : SQP 2015 (iii) The renal cortex has a dotted appearance.
Ans : COMP 2013
Excretion Egestion
(i) In summer, due to perspiration considerable
(a) It is the removal (a) It is the removal amount of water is lost. So, more water is
of metabolic of undigested reabsorbed in the kidney from the urine
wastes from the food material making it more concentrated.
body. from the body. (ii) The glomerular filtrate contains lots of
(b) It is related with (b) It is related with glucose, salt, etc., which are useful. In the
kidney. alimentary canal. proximal convoluted tubule of the nephron,
all the glucose is reabsorbed in the blood.
145. Excretion and Secretion. Therefore, glucose is normally not found in
urine.
Ans : SQP 2001
(iii) The renal cortex has dotted appearance
because it contains malpighian capsules.
Urea Secretion
– It is the removal – It is the production of 149. Renal Cortex and Renal Medulla
of nitrogenous chemical substances Ans : MAIN 2009
metabolic that is poured into
wastes from the the blood or thrown Renal cortex Renal Medulla
body. outside the body in
(a) It is the outer (a) It is the inner
the form of sweat
reddish region of brown region of
through the sweat
the kidney. the kidney.
pores.
(b) It contains (b) It has Henle’s
146. Urea and Urine convoluted Loop and
tubules and renal collecting ducts.
Ans : MAIN 2007
corpuscles.

Urea Urine (c) It looks granular. (c) It looks striated.

(a) It is a chemical (a) It is a mixture 150. Draw a labelled diagram of the longitudinal
compound. of metabolic section of the kidney.
wastes and other
substances. Ans : SQP 2009
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 275

(i) Label the parts numbered 1 to 4. (i) Label the parts 1— 4.

(ii) Why does part ‘2’ have a striped (ii) State the structural difference between part 1
appearance? and 2.
(iii) What is the fluid that passes down part (iii) What stage in urine formation occurs in part
‘4’ ? Name the main nitrogenous waste 3?
present in it. (iv) Name the liquid flowing through ‘X’.
(iv) Mention the structural and functional
Ans : MAIN 2012
units of kidneys.
(v) Name the two major steps in the (i) 1 - Afferent arteriole;
formation of the fluid mentioned in (iii). 2 - Efferent arteriole;
(b) Draw neat and labelled diagram of Malpighian 3 - Glomerulus;
Capsule. 4 - Bowman’s capsule
(ii) The diameter of afferent arteriole is more
Ans : COMP 2015
than efferent arteriole.
(a) (i) 1 – Cortex (iii) Ultrafiltration
2 – Medulla (iv) Glomerular filtrate
3 – Pelvis
4 – Ureter 158. The given diagram represents a nephron and its
(ii) Part 2 has striped appearance because blood supply. Study the diagram and answer the
the nephrons run about straight in this following questions :
region and conical pyramids are present.
(iii) The fluid that passes down from part
4 is urine. The main nitrogenous waste
present in it is urea.
(iv) The structural and functional unit of
kidney is nephron.
(v) The two major steps are:
1. Ultrafiltration
2. Selective reabsorption
(b) Malpighian Capsule

157. Study the diagram and answer the following (i) Label parts 1, 2, 3 and 4.
questions: (ii) State the reason for the high hydrostatic
pressure in the glomerulus.
(iii) Name the blood vessel which contains the
least amount of urea in this diagram.
(iv) Name the two main stages of urine formation.
(v) Name the part of the nephron which lies in
the renal medulla.
Ans : SQP 2014

(i) 1 – Collecting duct

2 – DCT (Distal Convoluted Tubes)
3 – Loop of Henle
CH 8 : THE EXCRETORY SYSTEM

(ii) Name the parts labelled 1, 2, 3 and 4.

(iii) Name the stages involved in the formation of
urine.
(iv) What is the technical term given to the
process occurring in 2 and 3 ? Briefly describe
the process.
(v) Give the reason for following statement. “In
summer, urine is slightly thicker than in
winter.”
Ans : SQP 2011

(i) Cortex of the kidney

(ii) 1. Afferent arteriole
2. Glomerulus
3. Bowman’s capsule
4. Efferent arteriole
(iii) Ultrafiltration, tubular reabsorption and
tubular secretion.
(iv) Ultrafiltration : When blood passes from (ii) What is the liquid entering part 1 ‘ called?
afferent arteriole to efferent arteriole having Name two substances present in this liquid
smaller diameter a pressure is built-up in the that are reabsorbed in the tubule.
glomerular capillaries, under this pressure all (iii) What is the fluid that comes to part ‘2’
the substances in the blood get filtered out called? Name the main nitrogenous waste in
through the capillary walls. This filtered out it.
liquid is called glomerular filtrate or nephric (iv) Mention the three main steps involved in
filtrate. the formation of the fluid mentioned in (iii)
(v) In summer urine is slightly thicker than in above.
winter, as in summer due to perspiration a (v) Name the substance which may be present in
good amount of water is released from the the fluid in part ‘2’ if a person suffers from
body as sweat. In sweat production, the sweat Diabetes mellitus.
glands absorb water from the surrounding Ans : SQP 2018
blood vessels, as a result the blood becomes
(i) Nephron/Uriniferous tubule
thicker and more concentrated with solutes.
(ii) Glomerular filtrate. Glucose and water soluble
To maintain the concentration and fluidity
salts
of the blood, water is absorbed into the
(iii) Urine ; Urea
blood (by osmosis from the renal tubules in
(iv) 1. Ultrafiltration
the kidney, hence less urine is formed and
2. Selective reabsorption
urination is less frequent and also the urine is
3. Tubular secretion
much thicker.
(v) Glucose
However, during winter; perspiration is less
and, therefore, water is not absorbed from 156. (a) The diagram given below shows a section of
the renal tubules in the kidney. Hence, urine a human kidney. Study the diagram carefully
remain thinner in winter as compared to that and answer the questions that follow :
in summer.

155. The diagram given below is that of a structure

present in a human kidney.
Study the same and answer the questions that
follow:
(i) Name the structure represented in the
diagram.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 277

contain them. gulation?

(v) Sugar (v) Which is the major nitrogenous waste product
in a human being ? How is it removed from
161. Given below is a simple diagram of the human the body ?
kidney cut open longitudinally. Answer the (vi) Name the procedure used in the working of
following questions : an artificial kidney.
Ans : SQP 2004

(i) Ureters carry the urine into the urinary

bladder where it is stored till it is thrown out
of the body.
(ii) It is a duct which carries urine from the
urinary bladder to the exterior.
(iii) Glucose is reabsorbed by blood capillaries
surrounding the nephron.
(iv) Excretion is the removal of toxic wastes from
the body while Osmoregulation is the process
(i) Give the definition of excretion. of maintaining the right amount of water and
(ii) Name the units of the kidney. proper ionic balance in the body.
(iii) Why does the cortex of the kidney show a (v) Major nitrogenous waste product in a human
‘dotted’ appearance ? being is urea. This urea is dissolved in water
(iv) Mention two functions of the kidney and is removed from the body in the form of
(v) Write two differences in the composition of urine.
the blood flowing through blood vessels A (vi) The procedure used in the working of an
and B. artificial kidney is called dialysis.
(vi) Name the outer part of the kidney containing
the Bowman’s capsules. 163. (i) What is osmoregulation ? How does it take
place in humans ?
Ans : MAIN 2016
(ii) Briefly describe the mechanism of urine
(i) Excretion is defined as the process of formation.
elimination of unwanted or even toxic by- (iii) State the vital functions of the human kidney.
products of metabolism from the body.
(ii) Nephrons/uriniferous tubules. Ans : COMP 2001

(iii) Because of the presence of Malpighian bodies. (i) Osmoregulation is the process of regulating
(iv) 1. Osmoregulation. water content and ion concentration in the
2. Removal and excretion of urea from the body of an organism is called osmoregulation.
blood. Process of osmoregulation in human beings
(v) Osmoregulation is related to the habitat of
an organism. In human beings, this function
No. Renal vein (A) Renal artery (B) is performed by the kidneys. Kidneys have
1. It contains less It contains more filtering units called nephrons which not
urea. urea. only remove toxic wastes but also help in the
reabsorption of useful products into the blood
2. It contains less It contains more
capillaries which surround the nephron. In
oxygen. oxygen.
this way kidneys remove toxic waste and also
3. It contains more It contains less control water balance and levels of mineral
carbon dioxide. carbon dioxide. ions in the body.
(vi) Cortex. (ii) Each kidney is made of excretory units called
nephrons. The waste material is brought to
162. (i) Where is urine carried through the ureters ? kidneys by the renal arteries. Blood is filtered
(ii) What is urethra ? (from the blood capillaries) into Bowman’s
(iii) What happens to glucose which enters the capsule. As this filtrate passes through the
nephron along with the filtrate ? tubular parts of nephron, useful products,
(iv) How excretion different from osmore- such as glucose, amino acids are reabsorbed
CH 8 : THE EXCRETORY SYSTEM

and potassium. It also maintains the water 1. High uric acid may indicate improper kidney
contents of blood constant. function.
(iii) Kidney does the following functions in the 2. Through ultrafiltration, reabsorption, and
human body : secretion.
(1) It separates the excretory products 3. The glomerulus filters the blood.
like urea, uric acid from the blood and 4. Urine is stored in the urinary bladder.
eliminates them as waste material in the
urine. 171. A patient with severe kidney damage is unable to
(2) Kidney maintains a constant composition urinate properly. The medical team plans to start
of blood. dialysis to remove harmful wastes from the blood.
(3) Kidney helps in maintaining the correct Without dialysis, the buildup of nitrogenous
pH balance by filtering the acidic waste can cause life-threatening conditions.
substance from blood. 1. What is dialysis?
2. What wastes do kidneys normally excrete?
3. What is the main function of the nephron?
4. What fluid balance process does the kidney
CASE BASED QUESTION manage?
Ans ::
1. Dialysis is a process to remove waste products
169. A 50-year-old man suffers from shortness of breath
when kidneys fail.
and has an abnormal buildup of fluid in his body.
2. Kidneys excrete urea, uric acid, and ammonia.
Doctors suspect kidney malfunction and warn of
3. The nephron filters blood and produces urine.
dropsy if untreated. They advise the patient to
4. The kidney manages osmoregulation.
undergo a detailed kidney function test to prevent
further complications. 172. A young athlete is diagnosed with dehydration due
1. What is dropsy? to excessive sweating during training. The doctor
2. Which organ helps in osmoregulation? explains that the kidneys are working harder to
3. What does the kidney regulate besides water retain water and maintain solute balance in the
balance? body. They advise increased water intake to avoid
4. What nitrogenous waste is removed by the dehydration.
kidneys? 1. What role do kidneys play in dehydration?
Ans :: 2. What waste does the skin excrete?
3. Which part of the kidney controls water
1. Dropsy is the accumulation of fluid in the
balance?
body due to improper kidney function.
4. What type of waste do kidneys filter out?
2. The kidneys help maintain water balance in
the body. Ans ::
3. The kidney regulates acid-base balance and 1. Kidneys conserve water during dehydration.
blood pressure. 2. The skin excretes sweat.
4. The kidney removes urea, uric acid, and 3. The distal tubules help regulate water
ammonia. balance.
4. Kidneys filter out nitrogenous wastes like
170. A 35-year-old individual experiences discomfort
urea.
when urinating. Tests show increased uric
acid levels in the body, pointing to a potential 173. A person is advised to avoid high-protein food due
issue with nitrogenous waste removal. Doctors to impaired kidney function, which could increase
recommend reducing foods high in purines to nitrogenous waste production. The doctor also
prevent further complications. suggests reducing salt intake to avoid putting
1. What does high uric acid indicate? additional pressure on the kidneys.
2. How does the kidney remove waste? 1. Why should the person avoid high-protein
3. What structure in the kidney filters blood? food?
4. Where is urine stored before being excreted? 2. What process removes nitrogenous waste?
Ans :: 3. Which organs are involved in excretion?
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 279

(iv) Name the two main organic constituents of (ii) Osmoregulation is the maintenance of a
the fluid that flows down the part labelled ‘3’. constant solute concentration within the
(v) Name the two major steps involved in the body. It is considered important because, if
formation of the fluid that passes down the we place animal cells in a hypertonic solution,
part labelled ‘3’. they lose water by osmosis and shrivel. If we
put them in a hypotonic solution they gain
water and may burst. Both situations are
harmful to cells, and so it is important that
animals maintain the solute concentration of
their body fluids within narrow limits.
(iii) Useful substances like glucose, amino acids,
etc., are reabsorbed by cells lining the tubules
nephridia and are passed into the blood.

168. (i) Briefly describe the mechanism of urine

formation in man.
(ii) In what way is kidney a homeostat organ ?
(iii) Write the functions of kidney.
Ans : SQP 2020

(i) Urine formation in man consists of three

Ans : SQP 2002
different stages :
(i) Excretory system, Circulatory system, (1) Ultrafiltration : This is the first stage of
Endocrine system urine formation when blood in the afferent
(ii) 1 – Left kidney; arteriole enters into the glomerulus with
2 – Dorsal aorta; great pressure and filters the liquid part
3 – Ureter; of the blood into the Bowman’s capsule
4 – Urinary bladder; which is called glomerular filtrate. This
5 – Urethra filtrate consists of water, urea, salts,
(iii) Nephron glucose and other solutes of plasma.
(iv) Urea and creatinine Corpuscles and other insoluble particles
(v) Ultrafiltration and selective reabsorption. are left behind in the glomerulus.
(2) Selective Reabsorption : This is the
167. (i) Explain, how the kidneys function. second stage of urine formation when
(ii) Define Osmoregulation. Why is it considered extra glucose and water are re-absorbed
important for an organism ? in the tubule which the body does not
(iii) What happens to the useful substances which want to lose. Normal concentration of
flow into nephridia along with the waste ? the blood remains constant during this
process as the urine passes through the
Ans : COMP 2011 renal tube.
(i) Kidney function involves two processes (3) Secretion : This is the last stage of
ultrafiltration and active transport. urine formation when excess vitamins,
Ultrafiltration is filtration under pressure: alcohols, drugs and dyes enter into the
blood is ‘squeezed’ to separate a fluid called urine from the blood capillaries by the
glomerular filtrate (often called simply the process of diffusion. Thus, all waste
filtrate). Active transport then modifies materials are removed from the body by
the filtrate, secreting some substances and urine formation and passing the urine out
reabsorbing others according to the needs of of the body.
the body. The result is that blood flows back (ii) Homeostasis means maintenance by an
into the body without much of its harmful organism of a constant internal environment.
waste. This waste, a solution containing urea, Kidney helps to maintain a steady or constant
salts and various other chemicals, is called state of internal atmosphere by excreting
urine. waste products and reabsorbing useful
substances like water and salts of sodium
CH 8 : THE EXCRETORY SYSTEM

by blood capillaries surrounding the nephron. kidneys. They eliminate all metabolic wastes,
The nephrons drain the waste into a space excess water and salt, thereby maintaining
inside kidney leading to the ureter. Human electrolyte and water equilibrium in the body.
urine contains water and nitrogenous
substances, most of which is urea. From the 165. Given below is a simple diagram of the human
ureter, urine passes into the urinary bladder kidney cut open longitudinally. Answer the
and is stored there till thrown out of the body. following questions:
(iii) Functions of human kidney :
(1) Kidneys remove toxic wastes from the
body.
(2) Kidneys help in the reabsorption of useful
products in the body.
(3) Kidneys help in regulating water content
and controlling water balance in the
body.
(4) Kidneys also control the levels of mineral
ions the body.

164. There is the diagram of a part of the nephron (i) Give the definition of excretion.
of the kidney. Study the same and answer the (ii) Name the functional unit of the kidney.
questions that follow: (iii) Why does the cortex of the kidney show a
(i) Name the parts labelled 1, 2 and 3. “Dotted” appearance?
(ii) Name the region in the kidney where the (iv) Mention two functions of the kidney.
given structure is present.
(v) Write the difference in the composition of the
(iii) What is the collective term used for 2 and 3? blood flowing through blood vessels A and B.
(iv) Why is the right kidney at a slightly lower
level than the left? Ans : COMP 2009

(v) Explain the term homeostasis. What is the (i) It is the process for removal of metabolic
role of the kidney in this? wastes from the body.
(ii) Nephrons
(iii) It is due to the presence of Malpighian
capsules.
(iv) Formation of urine and osmoregulation.
(v)

A - Renal Artery B - Renal Vein

1. It contains more 1. It contains less
urea urea
2. The blood 2. The blood flowing
flowing through it through it is
is oxygenated. deoxygenated.
Ans : MAIN 2017 3. It contains more 3. It contains less
salts, water, etc. salt, water, etc.
(i) 1 – Afferent arteriole;
2 – Glomerulus;
3 – Bowman’s capsule. 166. Given is the figure of certain organ and its
(ii) Cortex associated parts. Study the same and then answer
(iii) Malpighian capsule the questions that follow:
(iv) Liver occupies a large space. So, right kidney (i) Name all the organ systems shown completely
is slightly lower level than the left. or even partially.
(v) Homeostasis means keeping a constant (ii) Name the parts numbered 1 to 6.
internal environment irrespective of the (iii) Name the structural and functional unit of
outside environment. It is performed by the part marked 1.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 281

4. What condition occurs if urea builds up in

the blood?
Ans ::
1. High-protein food increases urea production.
2. Excretion removes nitrogenous waste.
3. The kidneys, liver, skin, and lungs.
4. This leads to Uremia.

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CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

CHAPTER 9
NERVOUS SYSTEM AND SENSE ORGANS

of another neuron separated by a fine gap.

SUMMARY Dendrites and axon are collectively called as
neuritis.
The speed of nerve impulse is 100 metres per
1. NERVOUS SYSTEM AND ITS FUNCTIONS
second while the electricity is conducted through
The nervous system provides the fastest means of a wire at a speed of about 1,50,000 km per second.
communication within the body so that suitable
responses to stimuli can be made at once. It
controls activities, functioning of our internal
organs, movements, perceptions and even our
thoughts and emotions. It receives information of
changes in the external environment and analyses
and interprets them to produce sensations. It also
receives information of changes in the interior
of the body and co-ordinates the activities of
visceral organs in the light of those changes;
thereby it helps to maintain the constancy of the
internal environment in the body. It enables us to 1.2 Nerves
think, remember and reason out. It controls and These are thread like white structures which
harmonises all voluntary muscular activities. emerge from the brain and spinal cord and branch
out to almost all parts of the body. It is formed
1.1 The unit of Nervous System-Neurons (nerve cells) of a bundle of nerve fibres (axons) enclosed in a
Neurons are the structural and functional unit tubular sheath. There are three kinds of nerves.
of nervous system and once they are formed in These are - sensory nerves containing only sensory
the embryo do not divide further because of the fibres bringing impulses from receptors to brain
absence of centrosome. Once dead, they are not or spinal cord. Motor nerves contain only motor
replaced. Every set of co-ordinated movements fibres carrying impulses to effector organs (muscles
whether skilled performances or routine tasks like or glands) from brain or spinal cord. Mixed nerves
cycling or driving a car, all involve the integrating carry both sensory and motor fibres.
powers of the nervous system. In mammals, the nervous system consists of
A neuron consists of the cell body (Perikaryon central nervous system (CNS), peripheral nervous
or cyton) which contains a nucleus surrounded by system (PNS) and autonomic nervous system
granular cytoplasm. There are certain branched (ANS). The CNS includes brain and spinal cord.
cytoplasmic projections of the cell body called The PNS includes sensory nerves that keeps the
dendrites. One of the dendrite extends and body in touch with the outside world along with
forms the axon of the neuron. Axon is a long the nerves that govern bodily responses to that
process from the cell body and in most neurons world. The ANS controls the internal environment
it is surrounded by a white insulating sheath and governs the involuntary activities.
called neurolemma. The end portions of axons
have swollen ends like bulbs which store certain 2. THE CENTRAL NERVOUS SYSTEM (CNS)
chemicals called neurotransmitters (acetylcholine All the parts of the nervous system which are
is one such neurotransmitter). There is a synapse, present along the median longitudinal axis
which is a point of contact between the terminal constitute the CNS. It includes the brain and
branches of the axon of a neuron with the dendrites spinal cord. Brain is the upper part of the CNS
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 283

which lies within the brain box. It is continued together by a transverse band of nerve
downwards as the spinal cord which is placed fibres called corpus callosum. The outer
within the vertebral canal. The brain and spinal layer of cerebrum known as cerebral
cord is protected by three successive layers of cortex is formed of gray matter and the
fibrous coverings (piamater, arachnoid mater inner of white matter. The surface of
and duramater) called Meninges. In-between the cerebrum shows many folds and grooves
layers of meninges a cerebrospinal fluid is present called gyri and sulci which increase the
which serves as shock absorbing medium and surface area to accommodate more nerve
protects the brain and rest of the CNS against cells and hence believed to be of greater
jerk and jolt. intelligence. The human cerebrum
performs many functions which are
2.1 The Brain localized in different parts.
The human brain is highly developed and is (iii) Diencephalon : It is a small lobe completely
largest among all animals. In an average it weighs covered superiorly by large cerebrum but
about 1350g approximately. It is made-up of visible from the inferior surface as a small
about 1000 billion neurons. An instrument called area. It lies between cerebrum and mid
Electroencephalogram (EEG) records the waves brain. It is distinguishable into two parts
of brain. the thalamus and hypothalamus.
Thalamus acts as relay centre for various
senses except smell. It also contains reflex
centres for muscular and glandular activities.
Hypothalamus controls water balance, fat
metabolism, eating, blood pressure, body
temperature, sleep and control of pituitary
gland, hunger, thirst, anger and pleasure.
(b) The Midbrain is significantly small about
2 cm long. It connects the hind brain with
forebrain and convey impulses.
(c) The Hindbrain consists of three parts :
cerebellum, medulla oblongata and pons
varolii. Medulla oblongata, pons varolii,
midbrain and hypothalamus are collectively
called as brain stem. Pons varolii carries
impulses from medulla oblongata to forebrain
and co-ordinates muscular movements on
both sides.
Cerebellum is the largest part of hind
brain present below the cerebrum and above
the medulla oblongata, behind the pons.
It consists of two large lateral lobes called
The human brain can be distinguished into three cerebellar hemispheres. Cerebellum helps to
regions, forebrain, midbrain and hindbrain. The maintain the balance or equilibrium during
hind brain continues into spinal cord. movements. It also controls and coordinates
(a) The Forebrain is the largest part of human the movements of various groups of muscles.
brain which is differentiated into three parts : Medulla oblongata extends from pons to
(i) Olfactory lobes : These are a pair of spinal cord. Most of the involuntary activities
poorly developed bodies which are visible of body viscera are controlled by different
from the ventral surface only since they areas of medulla oblongata.
are hidden beneath the cerebrum. They
2.2 The Spinal Cord
are concerned with sense of smell.
(ii) Cerebrum : It is the largest part of the The spinal cord is a long, unsegmented, cord
brain and consists of two lobes called like structure about 25 cm in length and 35 g in
cerebral hemispheres which are held weight. The distribution of matter in the spinal
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

9. The number of Spinal nerves in a human being Ans : MAIN 2010

are : The cochlea, ear ossicles, and tympanum are the

(a) 31 pairs (b) 10 pairs three main parts of the human ear that contribute
(c) 21 pairs (d) 30 pairs to hearing.
Ans : COMP 2013
Thus (d) is correct option.

The human body has 31 pairs of spinal nerves 14. A mixed nerve is one which
that connect the spinal cord to the periphery. (a) carries sensations from 2 or more different
Thus (a) is correct option. sense organs.
(b) has a common root but branches into two or
10. Aqueous humour is present between the : more nerves to different organs.
(a) Lens and Retina (c) has two or more roots from different parts of
(b) Iris and Lens brain.
(c) Cornea and Iris (d) contains both sensory and motor fibres.
(d) Cornea and Lens
Ans : MAIN 2005
Ans : MAIN 2018
A mixed nerve is any nerve that contains both
Aqueous humor is the liquid which is present sensory (afferent) and motor (efferent nerve
between eye lens and cornea. fibers)
Thus (d) is correct option. Thus (d) is correct option.
11. Organ of corti is present inside the : 15. The number of spinal nerves in a human being are
(a) Cochlea (a) 10 pairs (b) 31 pairs
(b) Semicircular canals (c) 21 pairs (d) 30 pairs
(c) Sacculus
Ans : COMP 2000
(d) Utriculus
The human body has 31 pairs of spinal nerves
Ans : COMP 2021
that connect the spinal cord to the periphery.
The organ of Corti, also known as the spiral Thus (b) is correct option.
organ, is located in the cochlea of the mammalian
inner ear. The cochlea is a fluid-filled, snail-like 16. From which of these, tears come?
structure that contains the organ of Corti, which (a) Eyeball
is responsible for hearing (b) Aqueous chamber
Thus (a) is correct option. (c) Lachrymal glands
(d) Vitreous chamber
12. A structure of neuron comprises of Ans : MAIN 2001
(a) cell body, dendrites, axon
(b) cell body, synaptic knob, ganglia Lachrymal glands are almond-shaped glands that
(c) synaptic vesicles, ganglia, dendrites produce and secrete tears through ducts that
(d) cell body, dendrites, ganglia empty onto the conjunctiva's surface.
Thus (c) is correct option.
Ans : COMP 2015
17. The organ that helps in hearing is
A neuron has three main parts: dendrites, an
(a) organ of Corti
axon, and a cell body or soma (see image below),
(b) cochlea
which can be represented as the branches, roots
(c) semicircular canals
and trunk of a tree, respectively.
(d) ear ossicles
Thus (a) is correct option.
Ans : SQP 2016
13. Which of the following parts of human ear
This action is passed onto the cochlea, a fluid-
contribute in hearing?
filled snail-like structure that contains the organ
(a) Semicircular canals, utriculus and sacculus
of Corti, the organ for hearing. It consists of
(b) Eustachian tube, tympanum and utriculus
tiny hair cells that line the cochlea. These cells
(c) Perilymph, ear ossicles and semicircular
translate vibrations into electrical impulses that
canals
are carried to the brain by sensory nerves.
(d) Cochlea, ear ossicles and tympanum
Thus (a) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 285

Structure of Eyeball : which contains opening through which the

The wall of eyeball is composed of three concentric nerve fibres from all the sensitive cells of the
layers : (i) Outer sclerotic, (ii) Middle choroids, retina converge and bundle together to leave
(iii) Inner retina. the eyeball in the form of optic nerves. There
(i) Sclerotic layer or Sclera : Made up of tough are no sensory cells in the blind spot and
fibrous tissue and is white making the white therefore this is the point of no vision and
portion on the front of the eye. It bulges out image striking it cannot be perceived.
and becomes transparent in the front region Lens of the Eyes :
where it covers the coloured part of the eye; It is a transparent, biconvex crystalline body
the cornea. The cornea derives oxygen by held by fibres called suspensory ligament which
diffusion therefore excessive use of contact attaches it to the ciliary body. There is no
lens is not recommended as it could lead to the blood in the lens. The lens refracts the light and
drying of the cornea. This cornea sometimes converges it on the retina. The lens of eye divides
becomes opaque (white) and non-functional the interior of the eye into two chambers - the
(defective) which can be then replaced by a aqueous chamber which is filled with a watery
healthy cornea from a donated eye. fluid called aqueous humour (keeps the lens
Covering the entire anterior surface of sclera moist and protects it from mechanical shocks)
is a thin membrane called conjunctiva which and vitreous chamber which is filled with a jelly
when gets infected by a virus turns this thin like substance called vitreous humour (maintains
membrane red and develops a condition called the shape of the eyeball). The humours contain
conjunctivitis. dissolved salts, proteins and glucose.
(ii) Choroid : This layer is richly supplied with
blood vessels for providing nourishment to Working of Eye :
the organ. It is dark black in colour and Light rays from the object enter our eyes through
darkens the inner side of eyeball. In front of conjunctiva, cornea, aqueous humour, lens and
eye choroid expands to form a ciliary body. vitreous humour. The curvature of cornea bend
The smooth muscles in the ciliary body alter and converge the light rays to form an image on
the shape of the lens. Continuous with the retina. The image formed on retina is inverted
choroids is a coloured disc of tissue called and real.
iris partially covering the lens and leaving a Sterioscopic (binocular) Vision :
circular opening in the centre called pupil. When both the eyes are focussed on the same
The blue, brown or black colour of eye refers object but from different angles it is called
to the colour of the iris. The iris contains binocular or stereoscopic vision. All monkeys,
radial muscles to widen and circular muscles apes and particularly man have binocular vision.
to constrict the pupil which regulates the This vision enables man to judge the distances
amount of light entering the eye. correctly and also provides depth to the image.
(iii) Retina : It is the innermost, light sensitive
Abnormalities or Defects of Eye :
layer of the eyeball covering the choroids
(i) Near or short sightedness (Myopia) : Near
and ending at the edge of the ciliary body.
vision is clear while distant vision is blurred.
It contains two types of photosensitive cells
It is because of the lens becomes too convex
called Rods and Cones. The rods contain the
or curved and eyeball of too great depth
pigment rhodopsin (visual purple) and are
(eyeball lengthened from front to back). It
concentrated more towards the periphery of
leads to decrease in the focal length of eye
retina. They respond to light of low intensity
lens and image of the distant object is formed
(dim light) and do not respond to colour.
in front of the retina. it is corrected by
The cones contain pigment iodopsin (visual
wearing concave lenses which causes parallel
violet) and are most densly concentrated in
rays of light to diverge before they converge
the yellow spot. Cones are specialized for
and focus on the retina. The power of glasses
colour vision and sharpness of vision in bright
used is mentioned in minus.
light. As a result the yellow spot is called as
(ii) Far or long sightedness (Hyperopia, old term
the area of the best or brightest vision of a
Hypermetropia) : Distant vision is clear while
normal eye. Lying below the yellow spot is
near vision is blurred. This is because the
a small area on the retina called blind spot
lens becomes less convex or too flattened and
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

cord is just reverse of that in the brain i.e. white a musical instrument, etc.
matter is outside and gray matter is in the centre. Significance of Reflexes :
The gray matter penetrates into the white matter (i) They are the spontaneous response to any
in the form of horns like the alphabet ‘H’. harmful stimulus thereby protecting from the
3. PERIPHERAL NERVOUS SYSTEM harm that could be done if delayed.
(ii) These relieve the burden of brain by
It consists of nerves which arise from CNS (brain automatically responding to routine stimuli.
and spinal cord) and connect different parts of (iii) Conditioned reflex such as the wild animals in
the body. It consists of Cranial nerves and Spinal a circus are trained to perform many strange
nerves. acts.
Cranial nerves are those nerves which arise
from the brain. In man there are 12 pairs of 6. SENSE ORGANS
cranial nerves. The cranial nerves may be sensory Sense organs are the sensory receptors found
(afferent), motor (efferent) or mixed in nature. associated together in systems. Several types
Spinal nerves are those nerves which arise from the of sense organs are present in human body.
spinal cord and are 31 pairs in number. These are These sense organs enable us to be aware of the
cervical, thoracic, lumbar, sacral and coccygeal conditions of the environment. The major sense
nerves. All spinal nerves are mixed nerves. organs in our body are eyes, ears, nose, tongue
4. AUTONOMIC NERVOUS SYSTEM and skin.

The part of nervous system which controls all 6.1 The Eyes (Sense organs of sight-photorceptors)
the involuntary activities of various body viscera Eyes are the sense organs for vision or sight. The
is called ANS. It is divided into two parts - two eyes are located in deep sockets or orbits on
Sympathetic and parasympathetic nervous system the front side of the head. Each eye is a spherical
which are antagonistic to each other. Sympathetic ball like structure called as eyeball. There are two
nervous system prepares the body for violent movable upper and lower eyelids that protects the
action during emergency while parasympathetic eye from any kind of injury and clean the surface
nervous system helps in re-establishing normal of eyeball by regular blinking. On the free margins
conditions after violent act is over. of eyelids in a row are present very small but thick
5. REFLEXES (INVOLUNTARY ACTIONS) hairs called eyelashes. They act as strainers and
do not allow dust and other foreign particles to
There are two types of action which occur in our enter in the eye. There are some arched eminences
body – Voluntary (under the control of our will of skin above the eyes and bear hair called as
power, non-spontaneous, non-automatic and are eyebrows. They protect the eyes from dust, sweat,
controlled by cerebrum of brain) and Involuntary water and direct rays of the sun.
actions (not under the control of our will power, Located at the upper sideward portion of the
spontaneous, automatic and without involvement orbit are present tear or lacrimal glands. Six or
of brain). twelve ducts of the gland pour the secretion over
the front surface.
5.1 Reflex Action
It is a spontaneous, involuntary, automatic,
mechanical and stereotyped response to any
sensory stimulus without the involvement of the
brain. These are of two types :
(i) Natural or inborn or simple or unconditioned
reflexes : It is one in which no previous
experience or learning is required. These are
inherited from parents. e.g. coughing, blinking
of eyes, swallowing etc.
(ii) Acquired or conditioned reflexes : It is
one which develops during lifetime due to
experience or learning. e.g. applying brakes,
using keys of keyboard of computers, playing
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 287
Ans : SQP 2025

Thus (b) is correct option.

5. Adjusting the focal length of the eye lens to view

objects at different distances is done by:
(a) Cornea
(b) Ieis
(c) Ciliary outgrips
(d) Sclera
Ans : MAIN 2024

The ciliary muscles are responsible for adjusting

the shape of the lens within the eye, which in turn
alters its focal length. This helps in focusing on
MULTIPLE CHOICE QUESTION objects at varying distances, allowing the eye to
accommodate near and far vision effectively.
Thus (c) is correct option.
1. The antiseptic present in tears: 6. The ear ossicle that transports sound vibrations
(a) Iodine to the inner ear:
(b) Hydrogen peroxide (a) Stapes
(c) Lysozyme (b) Mallets
(d) Lysosome (c) Incas
Ans : SQP 2025 (d) Cochlea
Thus (c) is correct option. Ans : MAIN 2024

2. The two cerebral hemispheres are joined by a The ear ossicle that transports sound vibrations
sheet of fibres called: to the inner ear is stapes. The stapes specifically
(a) Pons transfer these vibrations to the oval window,
(b) Corpus luteum where they are then transmitted into the fluid-
(c) Hypothalamus filled cochlea of the inner ear, initiating the
(d) Corpus callosum process of hearing.
Thus (a) is correct option.
Ans : SQP 2025
7. The ventral root ganglion of the spinal cord
Thus (d) is correct option.
contains cell bodies of the :
3. Rahul inserted a hairpin into his right ear to (a) Motor neuron
remove ear wax. He felt a sudden sharp pain with (b) Sensory neuron
loss of hearing. This was due to: (c) Intermediate neuron
(a) Rupture of eardrum (d) Association neuron
(b) Rupture of vestibule Ans : SQP 2013
(c) Rupture of cornea
(d) Rupture of pinna The ventral root ganglion of the spinal cord
contains cell bodies of the motor neuron.
Ans : SQP 2025 Thus (a) is correct option.
Thus (a) is correct option.
8. Which one of the following is mainly associated
4. Assertion (A) : Rods and Cones are photoreceptors with the maintenance of the posture ?
in the sclera of eyeball. (a) Cerebrum (b) Cerebellum
Reason (R) : Rods are sensitive to dim light. (c) Thalamus (d) Pons
(a) Assertion is True and Reason is False. Ans : MAIN 2015
(b) Assertion is False and Reason is True.
(c) Both Assertion and Reason are True. Cerebellum is mainly associated with the
(d) Both Assertion and Reason are False. maintenance of the posture.
Thus (b) is correct option.
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

eyeball of too short depth (eyeball shortened The human ear has three main divisions :
from front to back). It leads to increase in (i) The External ear : It consists of projecting
focal length of eye lens and thus image is part pinna and the auditory canal leading to
formed behind the retina. It is corrected by ear drum. Pinna collects sound waves and
wearing convex lens. The power of glasses direct these waves into external auditory
used is mentioned in plus. canal.
(iii) Astigmatism : Some parts of the object is (ii) The Middle ear : It is an air-filled, irregular
seen in focus while others are blurred. It is space called tympanic cavity. It opens into
corrected by cylindrical lenses. pharynx through Eustachian tube which acts
(iv) Presbyopia : It is due to loss of flexibility of as a ventilator to equalize pressure of air on
the lens, generally after the age of 40 years. It both sides of tympanic membrane. Running
creates difficulty in focusing on near objects. across the middle ear from tympanum to oval
It is corrected by convex lens. window is present a more or less mobile chain
(v) Cataract : The lens turns opaque and vision of three small bones called ear ossicles which
is cut down even to total blindness. The only are outer malleus, middle incus and inner
cure of cataract is the removal of defective stapes.
lens. (iii) Internal ear : It is represented by an irregular
(vi) Glaucoma : Over production of vitreous very delicate structure called membranous
humour increases pressure on the delicate labyrinth which has three parts :
retina and crushes its delicate cells causing (a) Semicircular canal - Helps in dynamic
blindness. An operation needs to be equilibrium
performed to drain excess fluid and restore (b) Vestibule
normal pressure. (c) Cochlear duct.
(vii) Night blindness : Difficulty to see in dim Main Functions of Ear :
or diffused light is called nightblindness. It The ear performs two unrelated functions hearing
is because of failure of formation of visual and equilibrium.
purple pigment by rod cells. Deficiency of
vitamin A causes this disease. 1. Hearing :
(viii) Colour blindness : Inability to distinguish External pinna collects the sound waves and after
between various colours is called colour concentrating passes on to tympanic membrane
blindness. It is a genetic disorder and is more through auditory canal. The tympanic membrane
common in males. starts vibrating. These vibrations are conveyed
to the membrane over fenestra ovalis through
6.2 The Ears (sense organ for hearing and equilibrium) the ear ossicles. The vibrations in the membrane
A pair of ears present on lateral sides of head, one over oval window are passed on to the perilymph
on either side behind each eye are the organs for in the upper scala of cochlea. These vibrations
perceiving the sound waves. The ears interpret are transmitted to the endolymph of middle
these sound waves and help in analyzing the scala and the basilar membrane starts vibrating.
pitch, quality, timbre, intensity and direction of The vibrating basilar membrane stimulates the
the sound waves. sensory (hair) cells of organ of corti. The sensory
cells convert the sound waves into nerve impulses
that are carried to the brain through auditory
nerve. It is the brain which analyses the pitch,
quality, timbre, intensity and direction of the
sound waves.

2. Equilibrium :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 289

18. In myopia, the image is formed Single axon arises from the cell body and may be
(a) on the retina enclosed in a myelin sheath and a neurilemma.
(b) before the retina Thus (a) is correct option.
(c) beyond the retina
(d) on the blind spot 23. A reflex arc in man is best described as movement
of stimuli from:
Ans : MAIN 2018
(a) Receptor cell, efferent, relaying neuron,
In nearsightedness, also called myopia, the image muscles of the body.
of a distant object is formed in front of the retina (b) Receptor cell, sensory nerve, relaying neuron,
and not at the retina. This defect arises because effector muscles.
the power of the eye is too large due to the (c) Receptor cell, spinal cord, motor neuron,
decrease in focal length of the crystalline lens. relaying neuron
Thus (b) is correct option. (d) Receptor cell, synapse, motor neuron, relaying
neuron.
19. The two hemispheres of the cerebrum are connected by
(a) corpus callosum Ans : SQP 2017

(b) corpus luteum A reflex arc in man is best described as the

(c) cerebullum movement of stimuli from receptor cells, sensory
(d) pons neurons, relaying neurons, and effector's muscles.
Ans : SQP 2023 Thus (b) is correct option.
The two cerebral hemispheres are joined together 24. It is a butterfly-shaped mass present in the spinal
by the corpus callosum. cord
Thus (a) is correct option. (a) white matter (b) grey matter
(c) dorsal root (d) ventral root
20. Which one of the following is responsible for
controlling the body temperature ? Ans : MAIN 2011

(a) Liver (b) Lung The butterfly-shaped mass present in the spinal
(c) Spinal cord (d) Hypothalamus cord is grey matter.
Ans : COMP 2009 Thus (b) is correct option.
Hypothalamus is the part of the brain that 25. A reflex arc in man is best described as movement
controls body temperature. It responds to internal of stimuli from
and external stimuli and makes adjustments to (a) receptor cell, efferent nerve, relaying neuron,
keep the body within one or two degrees of 98.6 muscles of the body
degrees. (b) receptor cell, spinal cord, motor neuron,
Thus (d) is correct option. relaying neuron
(c) receptor cell, sensory neuron, relaying neuron,
21. A point of contact between two neurons is termed
effector muscles
as
(d) receptor cell, synapse, motor neuron, relaying
(a) synapsis
neuron
(b) neuro motor junction
Ans : COMP 2019
(c) axon
(d) synapse A reflex arc in man is best described as the
movement of stimuli from receptor cells, sensory
Ans : MAIN 2014 neurons, relaying neurons, and effector's muscle
A point of contact between two neurons is termed Thus (c) is correct option.
Synapse.
26. Which of the following pairs of brain part is not
Thus (d) is correct option.
correctly matched with its function?
22. The insulating sheath covering the axon is called (a) Cerebellum: Balance of body
(a) neurilemma (b) plasmalemma (b) Cerebrum: Memory
(c) dura mater (d) pia mater (c) Medulla oblongata: Controls activities of
internal organs
Ans : COMP 2022
(d) Pons : Consciousness
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

Kidneys, skin, and lungs are excretory organs. 78. The ear ossicle in contact with oval window of
The heart and liver are not directly involved in inner ear.
excretion.
Ans : MAIN 1997
Thus (a) is correct option.
Stapes

79. Adjustment of eye in order to obtain a clear vision

of objects at different distances.
ONE MARK QUESTIONS
Ans : COMP 1997

Accommodation
DIRECTION : Name the following 80. The opening through which light enters the eye.
Ans : SQP 1998
70. The eye defect caused due to the shortening of the
eyeball from front to back Pupil
Ans : SQP 2006 81. The cells of the retina that are sensitive to colour.
Hypermetropia Ans : MAIN 1996

71. The region of distinct vision in the eye. Cone

Ans : MAIN 2006 82. The photosensitive pigment present in the rod
Macula/fovea/yellow spot cells of the retina.
Ans : MAIN 2009
72. The tube which connects the cavity of the middle
ear with the throat. Rhodopsin

Ans : COMP 2004 83. The internal nutritive layer of the eye which
Eustachian tube prevents reflection of light.
Ans : SQP 2009
73. The nerve which transmits impulses from the ear
to the brain. Choroid.

Ans : MAIN 2004 84. Transfers impulses from inner ear to brain.
Auditory nerve Ans : COMP 2003

74. The part of eye responsible for its shape. Auditory nerve

Ans : SQP 2003 85. The part of brain which is concerned with memory.
Vitreous humour Ans : COMP 2001

75. Helps to change the focal length of the eye lens Cerebrum

Ans : MAIN 2002 86. The protective covering of the brain.

Ciliary muscles Ans : MAIN 2001

76. The photosensitive pigment present in the rod Meninges

cells in the retina.
87. The junction between two nerve cells.
Ans : COMP 1998
Ans : SQP 2000
Rhodopsin
Synapse
77. The part of eye responsible for change in the size
88. The fluid that is present inside and outside the
of the pupil.
brain.
Ans : SQP 1997
Ans : COMP 1998
Iris Cerebrospinal fluid
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 291

35. The basic structural and functional unit of brain Thus (d) is correct option.
is :
(a) Nephron (b) Neuron 40. Which one of the following is mainly associated
(c) Spinal cord (d) Nerve with the maintenance of the posture?
(a) Cerebellum (b) Cerebrum
Ans : SQP 2005
(c) Thalamus (d) Pons
The basic structural and functional unit of the Ans : MAIN 2010
brain is the neuron, also known as a nerve cell.
Neurons are specialized cells that receive, process, Cerebellum is mainly associated with the
and transmit information in the form of electrical maintenance of the posture.
or chemical signals. Thus (a) is correct option.
Thus (b) is correct option.
41. The region where the image is sharpest is known
36. The ventral root ganglion of the spinal cord as
contains cell bodies of the (a) blind spot (b) rod region
(a) sensory neuron (c) fovea (d) retina
(b) intermediate neuron Ans : MAIN 2023
(c) motor neuron
The region where the image is sharpest is known
(d) association neuron
as the fovea.
Ans : MAIN 2013 Thus (c) is correct option.
The ventral root ganglion of the spinal cord
42. The largest part of the brain is
contains cell bodies of the motor neuron.
(a) pons (b) cerebrum
Thus (c) is correct option.
(c) cerebullum (d) medulla oblongata
37. Which one of the following forms the pigmented Ans : SQP 2001
layer in eye?
The largest part of the brain is cerebrum. The
(a) retina (b) choroid
cerebrum is the front of the brain containing the
(c) sclera (d) fovea
cerebral cortex on the outside and white matter
Ans : COMP 2002 at its center. The cerebrum is responsible for
Pigmented layer in the eye is called the choroid. coordination in movements and temperature
Thus (b) is correct option. regulation. It is also responsible for speech,
thinking and reasoning, problem-solving,
38. The outer layer of meninges is emotions, and learning. Sensory activities of sense
(a) piamater (b) arachnoid organs are also the function of the Cerebrum.
(c) neurilemma (d) duramater Thus (b) is correct option.
Ans : MAIN 2008
43. Cerebrum is a part of
The tough outer layer is called the dura mater. (a) forebrain (b) mid brain
Thus (d) is correct option. (c) neuron (d) hind brain

39. The control centre for respiration is Ans : COMP 2023

(a) cerebrum The forebrain is the largest part of the brain and
(b) cerebellum comprises the cerebral hemispheres.
(c) corpus callosum Hence, the cerebrum is a part of the forebrain and
(d) medulla oblongata is concerned with receiving impulses from sensory
organs.
Ans : SQP 2008
Thus (a) is correct option.
The respiration control center is located in the
medulla oblongata and pons of the hindbrain. 44. The organ in ear that helps to maintain
The primary respiratory center is the medullary equilibrium is
respiratory center, It comprises two groups of (a) cochlea (b) organ of Corti
neuronal cell bodies: dorsal and ventral respiratory (c) ear ossicles (d) semicircular canals
groups. Ans : MAIN 2016
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS
Ans : SQP 2016
This is the back of the brain. It coordinates
Pons is involved in the control of breathing, voluntary muscle movements and helps to
communication between different parts of the maintain posture, balance, and equilibrium.
brain, and sensations such as hearing, taste, Thus (b) is correct option.
and balance but not consciousness on a whole.
Consciousness is regulated by brain stem. 31. The photo receptive cell of the retina sensitive to
Thus (d) is correct option. colour
(a) rods (b) cones
27. A mixed nerve (c) organ of cortii (d) iris
(a) carries sensations from two or more different Ans : COMP 2013
sense organs
The photoreceptor cells of the retina sensitive to
(b) has a common root but branches into two
colour are Cones.
nerves to different organs
Thus (b) is correct option.
(c) contains both sensory and motor fibres
(d) has two or more roots from different parts of 32. Which of the following is true about neurilemma?
brain (a) The cell membrane around the nerve cell
Ans : MAIN 2022 (b) A layer of specialised neuroglia around myelin
sheath of nerve fibres
Contains both sensory and motor fibres.
(c) A layer of fatty substance around axon
Thus (c) is correct option.
(d) The connective tissue around a nerve tract
28. Which of the following parts of the brain continues Ans : COMP 2021
into spinal cord?
Neurilemma is a layer of specialized neuroglia
(a) Medulla oblongata
around the myelin sheath of nerve fibers.
(b) Cerebellum
Thus (b) is correct option.
(c) Pons
(d) Cerebrum 33. A synapse is found between
Ans : SQP 2017 (a) axon terminal and axon terminal
(b) dendrite and axon terminal
The medulla oblongata, the bottom-most part (c) dendrite and dendrite
of the brain, continues into the spinal cord. (d) All of the above
It's located in the hindbrain and acts as a
coordination pathway for nerve signals traveling Ans : MAIN 2022

to and from the body. The medulla oblongata In the central nervous system, a synapse is a
also helps control vital processes like breathing, small gap at the end of a neuron that allows a
heartbeat, and blood pressure, and plays a role in signal to flow from one neuron to the next. It
maintaining posture and reflexes. is the point where one neuron's axon meets the
Thus (a) is correct option. dendrite of another, allowing the two neurons to
communicate.
29. Which one of the following is mainly associated Thus (c) is correct option.
with the maintenance of the posture?
(a) cerebellum (b) cerebrum 34. Which of the following helps us to distinguish
(c) thalamus (d) pons colours?
(a) rods (b) cones
Ans : COMP 2015
(c) rhodopsin (d) all of the above
Cerebellum is mainly associated with the
Ans : MAIN 2019
maintenance of the posture.
Thus (a) is correct option. There are two types of photosensitive cells present
in the retina- (a) Rod cells and (b) Cone cells.
30. The part of the brain that coordinates skeletal Cone cells are cone-shaped and contain iodopsin
muscular movements is pigment. Cone cells help us to see objects under
(a) medulla oblongata (b) cerebellum bright light. They enable us to identify different
(c) cerebrum (d) pons colours of objects. Problems in cone cells cause
Ans : MAIN 2011 colour blindness.
Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 293
Ans : SQP 2004
55. A biology teacher explains to students that the
Chemicals which are released at the synaptic human ear contains three small bones, known
junction are called neurotransmitters. Synapse as ossicles, which play a crucial role in hearing.
is junction present between two neurons. Among these, the smallest one is responsible for
Neurotransmitters are released in the synaptic transmitting sound vibrations effectively. The
junction and are involved in the transmission of smallest ear ossicle is
impulses from one neuron to the next. (a) malleus (b) Stapes
Thus (c) is correct option. (c) incus (d) cochlea

52. During an eye checkup, the doctor explains that Ans : COMP 2004

a gel-like substance inside the eye helps maintain The smallest ear ossicle is Stapes
its shape and ensures proper functioning of the Thus (b) is correct option.
visual system. The structure that keeps the shape
of the eyeball 56. A student is learning about reflex actions in
(a) vitreous humour (b) aqueous humour biology class. The teacher explains that some
(c) vitreous chamber (d) aqueous chamber reflexes, like sneezing and blinking, are natural,
while others, such as salivation at the sight of
Ans : SQP 2018
food, are learned over time. Which of the following
The shape of the eyeball is maintained by aqueous is not a natural reflex action?
humour. The back part (posterior segment) (a) Knee-jerk
stretches from the lens's front surface to the (b) Blinking of eyes due to strong light
retina, acting as no-vision zones. (c) Salivation at the sight of food
Thus (a) is correct option. (d) Sneezing when any irritant enters the nose

53. A student is studying the spinal cord and learns Ans : SQP 2002

that the ventral root contains neurons that Salivation at the sight of food is not a natural
control voluntary movement in the body. The reflex action. It's a conditioned reflex, which
ventral root ganglion of the spinal cord contains means it's a learned response where a stimulus
cell bodies of the: is associated with a consequence. Childhood
(a) Sensory neuron conditioning contributes to our preference for
(b) Intermediate neuron pleasant foods.
(c) Motor neuron Thus (c) is correct option.
(d) Associated neuron
57. During an eye examination, the doctor explains
Ans : SQP 2002
to the patient that a clear fluid called aqueous
The ventral root ganglion of the spinal cord humour is found in the front part of the eye,
contains cell bodies of the motor neuron. helping maintain its shape and providing
Thus (c) is correct option. nutrients. Aqueous humour is present between
(a) lens and retina (b) cornea and lens
54. A biology student is taught that the nervous (c) cornea and iris (d) iris and lens
system is made up of specialized cells responsible
for transmitting signals throughout the body. Ans : COMP 2003

Which of the following is the functional unit of The Aqueous humour is present between the
the nervous system? cornea and lens.
(a) Cyton (b) Perikaryon Thus (b) is correct option.
(c) Axon (d) Neuron 58. An athlete reacts quickly to changes during
Ans : MAIN 2023 training. The coach explains that the nervous
system helps the body detect and respond to
Neurons are the structural and functional units of
external stimuli. Which of the following can be
the nervous system. The nervous system is made
considered as the function of nervous system?
up of billions of neurons. A neuron, also called a
(a) Irritability
nerve cell, is a cell within the body that receives,
(b) Conduction of enzymes
processes, and transmits information through
(c) To prepare the body against reactions
electrical and chemical signals.
(d) Receive stimuli
Thus (d) is correct option.
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

The vestibular apparatus of the inner ear consists Ans : COMP 2004

of a utricle, saccule, and three semicircular canals. The central nervous system (Brain & spinal cord)
The balance receptors (hair cells) are present is covered with three connective tissue layers called
in the utricle, saccule, and ampulla of three meninges. The outermost layer of meninges is the
semicircular canals. These semicircular canals are dura mater, the middle layer is the arachnoid
arranged right angle to each other. They are filled mater and the innermost layer is the pia mater.
with a liquid called endolymph. The vestibules Pia is the most delicate layer of meninges.
and three semicircular canals of the human inner Thus (d) is correct option.
ear maintain body balance.
Thus (d) is correct option. 49. A teacher explains that the color of the eye,
whether blue or black, depends on the part that
45. The reflex action is controlled through regulates the light entering the eye. Colour of the
(a) peripheral nervous system eye like blue or black is due to
(b) autonomic nervous system (a) sclera (b) choroid
(c) central nervous system (c) iris (d) retina
(d) None of the above
Ans : SQP 2011
Ans : MAIN 2021
Iris is the pigmented circular diaphragm attached
The reflex action is governed by the ''central to the ciliary body in front of the lens of the eye.
nervous system''. Reflex actions are under the It contains two types of muscles: circular muscles
control of the spinal cord. and radial muscles. The pigment of the iris gives
Thus (c) is correct option. colour to the eye such as black, blue, green,
brown, etc
46. Which of the following is mainly associated with Thus (c) is correct option.
the maintenance of the posture?
(a) Cerebellum (b) Cerebrum 50. An eye surgeon explains to a patient that when
(c) Thalamus (d) Pons an eye is donated, a specific part is commonly
Ans : COMP 2013
grafted to restore vision in those with corneal
damage. The part of eye which is grafted in a
Cerebellum is mainly associated with the needy patient from a donated eye is
maintenance of the posture. (a) cornea
Thus (a) is correct option. (b) conjunctiva
(c) choroid
47. In an anatomy class, students learn that the part
(d) ciliary muscles
of the eye responsible for detecting light and color
contains specialized cells called rods and cones. Ans : COMP 2012
The part of the human eye, where rod cells and Cornea is the tissue that is most frequently
cone cells are located is the donated and transplanted. It is a contact lens-
(a) cornea (b) retina sized, clear piece of tissue which is present in
(c) choroid (d) sclera front of the eye. It is practically impossible to
Ans : MAIN 2007 transplant the whole eye, as nerve fibers once cut
can never be reconnected.
Retina is the part of the human eye where rod
Thus (a) is correct option.
cells and cone cells are located.
Thus (b) is correct option. 51. A neuroscience student is learning how signals are
transmitted between nerve cells. The professor
48. A medical student studies the layers of the brain
explains that certain chemicals are released at
and learns that the innermost membrane protects
the synapse to help carry these signals across the
the brain's surface Which one of the following is
junction. Chemicals which are released at the
an innermost membrane that covers the brain?
synaptic junction are called
(a) arachnoid
(a) hormones
(b) duramater
(b) cerebrospinal fluid
(c) grey matter
(c) neurotransmitters
(d) piamater
(d) lymph
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 295
Ans : SQP 2014
Reflex type Example
The stomach, small intestine, pancreas, and liver
P Pulling your hand away from a are organs involved in digestion. Lungs and heart
hot object. are not directly involved in the digestive process.
Q Salivating when food is seen. Thus (b) is correct option.
Identify the correct pair of reflex types:
67. The teacher asked the class to name two sensory
(a) P – Conditioned reflex, Q – Unconditioned
organs.
reflex.
Raj said: Ears and skin.
(b) P – Unconditioned reflex, Q – Conditioned reflex.
Sonu said: Ears and tongue.
(c) P – Simple reflex, Q – Complex reflex.
Lata said: Nose and liver.
(d) P – Voluntary reflex, Q – Involuntary reflex.
Abhay said: Eyes and nose.
Ans : MAIN 2002 Who were correct?
Pulling the hand away from a hot object is an (a) Raj and Sonu.
unconditioned reflex, while salivating at the sight (b) Lata and Abhay.
of food is a conditioned reflex learned through (c) Raj and Abhay.
experience. (d) Sonu and Abhay.
Thus (b) is correct option. Ans : MAIN 2010

Eyes, ears, nose, tongue, and skin are the five

DIRECTION : Conversation Type Question main sensory organs. The liver is not a sensory
organ.
65. A science teacher asked her students to give two Thus (d) is correct option.
examples of reflex actions.
Raj said: Blinking of eyes and coughing. 68. A teacher asked her students to give two examples
Sonu said: Writing and blinking of eyes. of types of joints in the human body.
Lata said: Sneezing and pulling hand away from Raj said: Hinge joint and ball and socket joint.
a hot object. Sonu said: Pivot joint and gliding joint.
Abhay said: Playing a musical instrument and Lata said: Fibrous joint and heart.
yawning. Abhay said: Ball and socket joint and hinge joint.
Who were correct? Who were correct?
(a) Raj and Lata. (a) Raj and Abhay.
(b) Sonu and Abhay (b) Lata and Sonu.
(c) Lata and Sonu. (c) Sonu and Raj.
(d) Abhay and Raj. (d) Lata and Abhay.

Ans : COMP 2018

Ans : COMP 2006

Blinking of eyes, coughing, sneezing, and pulling Hinge joint, ball and socket joint, pivot joint, and
hand away from a hot object are examples of gliding joint are types of joints. The heart is not
reflex actions. Writing and playing a musical a joint.
instrument are voluntary actions. Thus (a) is correct option.
Thus (a) is correct option. 69. A biology teacher asked her students to name two
66. A teacher asked her students to identify two excretory organs in humans.
organs involved in digestion. Raj said: Kidneys and lungs.
Raj said: Stomach and lungs. Sonu said: Skin and heart.
Sonu said: Small intestine and pancreas. Lata said: Lungs and liver.
Lata said: Stomach and liver. Abhay said: Kidneys and skin.
Abhay said: Heart and pancreas. Who were correct?
Who were correct? (a) Raj and Abhay.
(a) Raj and Sonu. (b) Sonu and Lata.
(b) Sonu and Lata. (c) Lata and Abhay.
(c) Lata and Abhay. (d) Raj and Sonu.
(d) Sonu and Abhay. Ans : SQP 2002
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

148. Semicircular canals, malleus, cochlea, 157. Cranial nerves arise from brain.
utriculus,sacculus.
Ans : MAIN 2017
Ans : MAIN 2004
True
Parts of inner ear. Malleus.
158. Impulses travel much more rapidly along
149. Myopia, hypermetropia, xerophthalmia, myelinated nerve.
astigmatism.
Ans : SQP 2022
Ans : COMP 2002
True
Disease of eye. Xerophthalmia.
159. ANS is completely independent of CNS.
150. Myopia, cataract, hypermetropia, squint,
Ans : MAIN 2013
cretinism.
False
Ans : SQP 2010

Disorders of eye. Cretinism 160. All nerve fibres arising from the spinal cord are
mixed nerves.
151. Malleus, Iris, Stapes, Incus.
Ans : COMP 2009
Ans : MAIN 2016
False
Iris, All others are ear ossicles.
161. The element needed for transmission of nerve
152. Aqueous humour, Vitreous humour, Iris, Central impulse is sodium.
canal
Ans : COMP 2016
Ans : SQP 2017
True
ODD : Central canal
CATEGORY : Rest are concerned with eyes 162. Salivation at the smell of food is a natural reflex.
Ans : SQP 2002
153. Dendrites, Medullary sheath, Axon, spinal cord.
False
Ans : MAIN 2018

Odd term - Spinal cord, 163. In the spinal cord gray matter is inside.
Category - Parts of Neuron Ans : MAIN 2004

True
DIRECTION : True or false. Insert a word if false.
164. Reflex actions involve brain.
154. A reflex action is a spontaneous response to a Ans : SQP 2008
stimulus.
False
Ans : COMP 2004
165. Myelin sheath helps in the insulation of axon of
True.
neurons.
155. All voluntary actions are controlled by the Ans : COMP 2015
cerebellum.
True
Ans : SQP 2009
166. A convex lens is used for correcting myopia.
False. All voluntary actions are controlled by the
cerebrum. Ans : MAIN 2011

False
156. Dilation of the pupil is brought about by the
sympathetic nervous system. 167. Deafness is caused due to rupturing of pinna.
Ans : COMP 2010 Ans : SQP 2004

True. False
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 297

89. The biological term given to the protective Corpus callosum

membrane of the brain.
100. Response to a stimulus Without intervention of
Ans : MAIN 2009
the will of an animal.
Meninges Ans : MAIN 2020

90. The part of the brain that carries impulses from Reflex action
one hemisphere of the cerebellum to the other.
101. Most important part of the nervous system.
Ans : SQP 2016
Ans : COMP 2008
Pons varolii
Brain
91. Inflammation of meninges.
102. The part of brain associated with intelligence,
Ans : COMP 2010 sight, hearing and speech.
Meningitis Ans : COMP 2003

92. Protective covering of the brain and spinal cord. Cerebral cortex
Ans : MAIN 1997 103. Two types of matter present in brain and spinal
Meninges cord.
Ans : SQP 2015
93. The layer of the eyeball that forms the transparent
Cornea. Gray and white matter

Ans : SQP 2018 104. Wave of electrical disturbance that sweeps over
Sclera/sclerotic layer/sclerotic coat/scleroid the nerve cell.
Ans : COMP 2011
94. The membrane covering the brain and spinal cord.
Impulse
Ans : MAIN 2010

Meninges 105. The part of human brain which control body

temperature.
95. The part of autonomic nervous system which Ans : MAIN 2019
prepares the body to prepare for adverse
conditions. Hypothalamus

Ans : COMP 2017 106. The nerve that carries impulses from brain to
Sympathetic various tissues.
Ans : SQP 2023
96. A neuro transmitter.
Efferent nerve.
Ans : SQP 2020

Acetylcholine 107. The fluid filled in the space between the lens and
the retina.
97. The cytoplasmic processes of the cell body of a Ans : COMP 2021
neuron.
Aqueous humou
Ans : MAIN 2023

Dendrites 108. The soft vascular – middle layer of the eye.

Ans : MAIN 2014
98. A collection of several neurons.
Choroid
Ans : COMP 2019
109. The structural and functional unit of nervous
Nerve
system.
99. The tissue that connects two cerebral hemispheres. Ans : SQP 2012

Ans : SQP 2022 Neurons

CH 9 : NERVOUS SYSTEM AND SENSE ORGANS
Ans : SQP 2018
Identify the correct pair of sensory receptors:
The nervous system's main function is to send (a) P – Rods, Q – Cochlea.
messages between the brain and the body, (b) P – Cones, Q – Cochlea.
regulating thoughts, memory, feelings, movements, (c) P – Rods, Q – Organ of Corti.
balance, and coordination. (d) P – Cones, Q – Semicircular Canal.
Thus (d) is correct option. Ans : MAIN 2015

59. A student visits the eye doctor with sensitivity Cones are responsible for detecting light and
to bright light. The doctor explains that the color, while the cochlea detects sound vibrations
circular opening in the center of the iris controls in the inner ear.
the amount of light entering the eye. The circular Thus (b) is correct option.
opening in the centre of iris :
(a) Lens (b) Cornea 62. Neha studied different types of nerves and their
(c) Sclera (d) Pupil functions as follows:

Ans : SQP 2021 Nerve Type Function

How the eyes work - Vision Initiative The circular P Carries impulses from sensory
opening in the center of the iris is called the pupil. receptors to the brain.
The pupil allows light to enter the eye and controls Q Carries impulses from the brain
the amount of light that does so. The pupil's size to muscles and glands.
changes to let more or less light in by working
with the iris's dilator and sphincter muscles Identify the correct pair of nerve types:
Thus (d) is correct option. (a) P – Motor nerves, Q – Mixed nerves.
(b) P – Sensory nerves, Q – Motor nerves.
(c) P – Mixed nerves, Q – Sensory nerves.
DIRECTION : Matching Type Questions (d) P – Autonomic nerves, Q – Sensory nerves.
60. Suresh studied the structure of the brain and Ans : COMP 2011
tabulated the functions as follows: Sensory nerves carry signals from sensory
receptors to the brain, while motor nerves carry
Brain Region Function on the Body
impulses from the brain to muscles and glands.
P Controls balance and Thus (b) is correct option.
coordination of muscles.
63. Ravi studied the parts of the ear and their
Q Regulates body temperature
functions as follows:
and water balance.
Identify the correct pair of brain regions: Ear part Function
(a) P – Cerebellum, Q – Hypothalamus.
P Amplifies sound vibrations.
(b) P – Medulla Oblongata, Q – Thalamus.
(c) P – Cerebrum, Q – Hypothalamus. Q Maintains balance and posture.
(d) P – Pons, Q – Cerebrum.
Identify the correct pair of ear parts:
Ans : SQP 2019 (a) P – Cochlea, Q – Semicircular canals.
The cerebellum controls balance and muscle (b) P – Auditory Canal, Q – Eustachian Tube.
coordination, while the hypothalamus regulates (c) P – Ear Ossicles, Q – Semicircular canals.
body temperature and water balance. (d) P – Tympanic Membrane, Q – Cochlea.
Thus (a) is correct option. Ans : SQP 2007

61. Priya studied the sensory receptors in the body The ear ossicles (malleus, incus, stapes) amplify
and tabulated the details as follows: sound vibrations, while the semicircular canals are
responsible for maintaining balance and posture.
Sensory Function Thus (c) is correct option.
Receptor
P Detects light intensity and color. 64. Anil studied reflex actions and their significance
as follows:
Q Detects sound vibrations.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 299

131. Name the nerve that transmits impulses to the Effector, Association Neuron. (pathway of a nerve
brain from : impulse)
(a) Ear
Ans : MAIN 2010
(b) Eye
Receptor, Sensory Neuron, Association of Neuron,
Ans : SQP 2021
Motor Neuron, Effector.
(a) Auditory nerve
(b) Optic nerve 140. Receptor, Spinal cord, Effector, Motor neuron,
Sensory neuron.
132. Name the kind of lens required to correct Myopia.
Ans : SQP 2017
Ans : SQP 2017
Receptor, Sensory neuron, Spinal cord, Motor
Concave lens. neuron, Effector.

133. Name the layer of the eyeball that provide 141. Cochlea, Malleus, Pinna, Stapes, Incus.
nourishment to the eye.
Ans : COMP 2017
Ans : SQP 2019
Pinna, Malleus, Incus, Stapes, Cochlea.
Choroid
DIRECTION : Write the category and the odd one
DIRECTION : Write in logical sequence : out.

134. Auditory canal, Organ of Corti, Stapes, Malleus. 142. Coughing, sneezing, blinking, eating.
Ans : SQP 2025 Ans : MAIN 2003

Auditory canal, Malleus, Stapes, Organ of Corti

Category Odd one
135. Ear ossicles, oval window, tympanum, auditory Simple reflex Eating
canal, cochlea.
Ans : COMP 2006 143. Corpus luteum, corpus callosum, pons, cere
Auditory canal, tympanum, ear ossicles, oval bellum.
window, cochlea. Ans : SQP 2003

136. Yellow spot, conjunctiva, pupil, cornea, lens, Part of brain - Corpus luteum
vitreous humour, aqueous humour.
144. Pleura, pericardium, meninges, spinal cord.
Ans : MAIN 2005
Ans : MAIN 2002
Conjunctiva, cornea, aqueous humour, pupil, lens,
Protective coverings - Spinal cord
vitreous humour, yellow spot.
145. Pons, cerebellum, medulla oblongata, cerebrum.
137. Pupil, Yellow Spot, Cornea, Lens, Aqueous
humour. (path of entry of light into the eye from Ans : SQP 2000
an object) Parts of hind brain-Cerebrum
Ans : SQP 2010
146. Blinking, Knitting without looking, Smiling,
Cornea, aqueous humour, pupil, lens, yellow spot. Blushing, Crying.
138. Dorsal root ganglion, receptor, effector, ventral Ans : COMP 2010
root ganglion, associated neuron. Reflex actions - Smiling
Ans : MAIN 2005
147. Axon, Dendron, Photon, Cyton.
Receptor, dorsal root ganglion, associated neuron,
ventral root ganglion, effector Ans : SQP 2019

Odd term - Photon

139. Motor neuron, Receptor, Sensory Neuron, Category - Others are parts of nerve cell
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

110. Long thread like part of the nerve cell. DIRECTION : Give exact location and function of :
Ans : COMP 2019
120. Pinna
Axon
Ans : COMP 2006
111. The structures present in hind brain. Side of head, collects sound waves.
Ans : MAIN 2000
121. Ear ossicles
Medulla oblongata and cerebellum
Ans : SQP 2001
112. The defect of eye caused due to uneven curvature Middle ear, increases the magnitude of vibrations.
of the cornea.
Ans : COMP 2002
122. Fovea

Astigmatism Ans : COMP 2001

Axis of eye in retina, more clear and distinct

113. The photosensitive pigment present in the rod image is formed.
cells of retina.
Ans : SQP 2005
123. Organ of Corti

Rhodopsin Ans : MAIN 2011

Cochlea (inner ear)

114. The structure meant for the constriction of pupil
in bright light. 124. Corpus callosum.
Ans : MAIN 2013 Ans : SQP 2019, 2013

Iris Between two cerebral hemispheres of cerebrum.

115. The structure that has a sensory organ called 125. Myelin sheath.
organ of corti.
Ans : MAIN 2017
Ans : COMP 2018
Inner sheath around the axon of a neuron.
Cochlea
126. Incus.
116. The muscles which help in alteration of shape of
Ans : COMP 2013
the lens.
Inner ear.
Ans : SQP 2023

127. Lacrimal gland

Ciliary muscles
Ans : MAIN 2018
117. The bony socket in which the eye is well protected.
Upper side portion of the orbit of eye
Ans : MAIN 2020
128. Malleus
Orbit
Ans : COMP 2018
118. The nerves which transmit impulses from ear to
Middle ear attached to tympanum and incus.
the brain.
Ans : SQP 2021 129. Incus.
Ans : SQP 2019
Auditory nerve
Between malleus and stapes.
119. The inner sensitive coat of eyeball.
130. Name the three membranous coverings of the
Ans : COMP 2015
human brain.
Retina Ans : MAIN 2021

Piamater, Arachnoid, Duramater

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 301

168. Cochlea is concerned with sense of balance. DIRECTION : The statement given below is
incorrect. Rewrite the correct statement by changing
Ans : MAIN 2010
the underlined word of the statement.
False
177. Maintaining balance of the body and coordinating
169. Fovea centralis is the area of brightest vision.
muscular activities is carried out by the cerebrum.
Ans : COMP 2010
Ans : SQP 2019
True
Maintaining balance of the body and coordinating
170. The enzyme present in tears which prevents eye muscular activities is carried out by the
infection is lysosomes. Cerebellum.

Ans : MAIN 2018 178. Gyri and Sulci are the folds of Cerebellum.
False Ans : COMP 2017

171. The fluid in which the membranous labyrinth of Gyri and Sulci are the folds of Cerebrum.
inner ear floats is perilymph.
179. The outermost layer of Meninges is Pia mater.
Ans : COMP 2023
Ans : MAIN 2018
True
The outermost layer of Meninges is Dura mater
172. The utricule and saccule are the two sacs that lie
180. Deafness is caused due to the rupturing of the
in the vestibule of ear.
Pinna.
Ans : SQP 2009
Ans : COMP 2017
True Deafness is caused due to rupturing of the
eardrum/ tympanum.
173. The semicircular canals are associated with static
equilibrium. 181. The part of the eye which can be donated from a
Ans : COMP 2019 clinically dead person is the Retina.
False Ans : MAIN 2019

The part of the eye which can be donated from a

174. In presbyopia loss of elasticity in the lens occurs
clinically dead person is cornea.
with ageing.
Ans : MAIN 2021
DIRECTION : Give appropriate biological/technical
True terms for the following :
175. James Langley discovered autonomic nervous 182. The antiseptic substance in tears.
system.
Ans : SQP 2017
Ans : SQP 2002
Lysozymes
True
183. The fluid present between the layers of meninges.
DIRECTION : Rewrite and complete the following Ans : COMP 2013
sentences by inserting the correct word in the space Cerebrospinal fluid
indicated :
184. The change in an organism resulting due to
176. A fluid that occupies the larger cavity of the eye stimulus.
ball behind the lens is______ Ans : MAIN 2013

Ans : MAIN 2015 Response

A fluid that occupies the larger cavity of the eye
185. The fluid which fills the central canal and spinal
ball behind the lens is vitreous humour.
cord.
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

233. Injury to medulla oblongata results in sudden Ans : MAIN 2017

death. 1. Outer duramater

Ans : COMP 2017
2. Middle arachnoid
3. Inner piamater
Medulla oblongata is the centre for involuntary
actions such as heart beat, breathing, etc., so 243. State the three parts (sections) of embryonic
injury to it causes sudden death. brain in vertebrates.

234. Brain and spinal cord are considered as the central Ans : SQP 2013

nervous system. 1. Forebrain

Ans : SQP 2011
2. Midbrain
3. Hindbrain
Since they control all activities of body by cranial
nerves and spinal nerves. 244. What is the average weight of an adult human
brain?
DIRECTION : Categorize the following reflexes : Ans : COMP 2016

1350 to 1400 grams.

235. Knee jerk
245. State the four lobes of cerebral hemispheres.
Ans : MAIN 2019

Natural Ans : MAIN 2020

1. Frontal
236. Quick closing of eyelids of eye 2. Parietal
Ans : COMP 2012 3. Temporal
4. Occipital
Natural
246. What are the three parts of brain stem ?
237. Applying brakes of a car
Ans : SQP 2014
Ans : SQP 2022
1. Midbrain
Conditioned
2. Pons varolii
238. Knitting without looking 3. Medulla oblongata

Ans : MAIN 2023 247. What is hypothalamus ?

Conditioned Ans : MAIN 2018

239. Contraction of Iris of eye It is that part of brain which forms the floor of
diencephalon made of gray matter.
Ans : COMP 2018

Conditioned 248. What are the components of reflex arc ?

Ans : COMP 2011
240. Sneezing
1. Receptor organ
Ans : SQP 2008
2. Sensory neuron
Unconditioned 3. Associated neuron
4. Motor neuron
241. Define brain stem. 5. Effector organ.
Ans : MAIN 2015
249. Make a list of functions of the following parts of
The brain stem is the stem like part of brain that the brain :
connects the cerebral hemispheres with the spinal 1. Cerebrum 2. Diencephalon
cord. 3. Midbrain 4. Cerebellum
5. Pons 6. Medulla oblongata
242. Name the three membranes (meninges) that
protect and surround the brain. Ans : SQP 2014
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 303

(i) Choroid Sclerotic (i) Medulla oblongata Cerebellum

Absorbs light and Provides and Concerned with Regulates and
prevention of total maintains shape of respiratory coordinates
internal reflection eye ball. movements, heart muscular
that may cause beat and dilation of contraction and
blurring of image. blood vessels. body balance.
(ii) Dynamic balance Static balance (ii) Cerebrum Spinal cord
The sensory cells in The sensory cells Cytons outside and Axon outside and
cristae of internal in ear which are axons inside. cyton inside.
ear are concerned located in Maculae (iii) Cerebrum Cerebellum
with balance while of vestibule are
body is in motion. responsible for Seat of intelligence, Coordinates
static balance in memory and muscular activities
human beings by control of voluntary and maintains body
detecting change in activities. balance.
the head or body (iv) Sensory neuron Motor neuron
at rest. Concernecd Conveys impulse Carries message
with positional from receptors to from CNS to
balance with respect CNS. effector.
to gravity.
(iii) Rod cells Cone cells 206. Explain the difference between sensory nerve and
a motor nerve.
Rhodospin Iodospin
Ans : COMP 2005
(iv) Myopia Hypermetropia
Lens too convex. Flattened condition Sensory nerve Motor nerve
of lens. Dendrites longer than Axons longer than
axon and made-up of dendrites and made-up
204. Cerebrum and Spinal cord. (Arrangement of unipolar neuron. of multipolar neuron.
nerve cells).
207. With reference to the functioning of the eye,
Ans : MAIN 2009 answer the questions that follow :
(i) What is meant by power of accommodation
Cerebrum Spinal cord of the eye ?
Outer part contains cell Outer part contains (ii) What is the shape of the lens during (1) near
bodies or cyton giving axon giving a white vision (2) distant vision ?
a grayish appearance appearance and inner (iii) Name the two structures in the eye responsible
and inner part contains part contains cell for bringing about the change in the shape of
axon giving white bodies or cyton giving the lens.
appearance. white appearance. (iv) Name the cells of the retina and their
respective pigments which get activated (1)
in the dark (2) in light.
205. Differentiate between the following on the basis of
what is indicated within the brackets : Ans : SQP 2011
(i) Medulla oblongata and Cerebellum (function). (i) Abilities of the eye to see objects equally clear
(ii) Cerebrum and Spinal cord (arrangement of from various distances.
cyton and axons of neurons). (ii) 1. less convex or too flattened
(iii) Cerebrum and Cerebellum (function). 2. too convex or curved
(iv) Sensory and Motor neuron (function). (iii) 1. Suspensory ligaments
2. Ciliary body
Ans : COMP 2010, 2005, 2004, 1999, 1997 (iv) 1. Rod cells ; Rhodopsin
2. Cone cells ; Iodopsin
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS
Ans : MAIN 2010
195. Semicircular canal
Cerebrospinal fluid Ans : MAIN 2017

186. The breathing centre of the brain. Concerned with dynamic equilibrium of the body.
Ans : SQP 2019
196. Pinna
Medulla oblongata Ans : COMP 2021

187. The lower part of brain which contains reflex To receive the vibrations and transmit them to
centre. the auditory canal.
Ans : COMP 2021
197. Eardrum
Spinal cord Ans : SQP 2023

188. The taste for which the back of tongue is most To receive the vibrations from auditory canal and
sensitive. transmit to ear ossicles.
Ans : MAIN 2003
198. Wax in the ear
Bitter Ans : COMP 2016

To trap dust particles and micro organisms.

DIRECTION : State the main functions of the
following 199. Eustachian tube
Ans : MAIN 2022
189. Medulla Oblongata
Helps in equalizing air pressure on either side of
Ans : SQP 2019
the eardrum.
Controls involuntary activities.

190. Ear ossicles DIRECTION : Mention the exact location of the

following.
Ans : COMP 2015

The three ear ossicles form a leverage system 200. Semi-circular canals
which transmit and amplify sound waves from Ans : COMP 2017
external ear to the internal ear.
Internal ear above utriculus.
191. Eustachian tube
201. Eustachian tube.
Ans : SQP 2016
Ans : SQP 2017
Eustachian tube equalizes air pressure on either
side of the ear drum. Between middle ear and pharynx.

192. Eustachian tube. 202. Structures Organ of Corti

Ans : COMP 2016 Ans : MAIN 2015

Act as ventilators to equalize air pressure on the Organ of corti is located in the basilar membrane
two sides of tympanum. of scala media of cochlea of ear.

193. Tears.
DIRECTION : Differentiate between :
Ans : MAIN 2019

Helps in killing germs, lubricates surface of eye. 203. (i) Choroid and sclerotic layers of eye (function).
(ii) Dynamic balance and static balance
194. Optic nerve (Definition).
Ans : SQP 2012
(iii) Rod and cone cells (pigment).
(iv) Myopia and hypermetropia (Cause of defect).
Carries impulses from eye to brain
Ans : COMP 2010, 2006, 2004, 1998
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 305

216. Mention two functions of the choroids coat in the Ans : SQP 2000

eye. Rods
Ans : COMP 1997
225. Point of no vision in the retina of eye is______
Choroid forms nutritive layer of eye. Contains iris. (yellow spot/blind spot).
It prevents reflection of light inside the eye. Ans : MAIN 2010

217. Differentiate on the basis of what is mentioned Blind spot

within brackets : Rod cells and cone cells (pigment)
226. Capacity of eye to focus at different distances
Ans : SQP 2016 is called power of______(accommodation/
Rod cells contain rhodopsin pigment whereas supervision).
cone cells contain iodopsin pigment. Ans : SQP 2005

218. Briefly explain Power of accommodation. Accommodation

Ans : MAIN 2016 227. The three small bones in the middle ear are
Ability of the eye to see the object equally collectively called______(occipitals / ossicles).
clear from various distances is called Power of Ans : COMP 2002
accommodation.
Ossicles
219. Give biological explanations for the following :
228. In_______a person cannot distinguish
We should not put sharp objects into our ears.
between red and greeti colour (colour-blindness/
Ans : MAIN 2018 nightblindness).
Tympanum is very delicate and sharp object may Ans : MAIN 2009
rupture them leading to deafness. Colourblindness

DIRECTION : Fill up the blanks with suitable words: 229. ______is the largest part of brain.
Ans : SQP 2012
220. ______receive information from sensory Cerebrum
receptors and transmit it to the central nervous
system.
DIRECTION : Give logical reasons for the following :
Ans : COMP 2021

Sensory neurons 230. Old people are unable to perceive taste easily.

221. Nervous system has two main functions to initiate Ans : MAIN 2010

and co-ordinate response to the______and to Old people are unable to perceive taste easily
maintain______. due to weakening of olfactory sensation and taste
Ans : SQP 2014
buds.

External environment ; internal homeostasis 231. The outer portion of the brain appears gray while
inner portion white.
222. The cavities of brain are called______.
Ans : SQP 2013
Ans : MAIN 2022
The outer portion of brain is made up of gray
Ventricles matter (cytons) while the inner portion consists
of white matter (axons).
223. Conditioned reflex can be exampled by______.
Ans : COMP 2020 232. The brain is ordinarily free from shock.
Pulling away hand on touching a hot plate Ans : COMP 2019

Brain is protected by cranium and a fluid

224. ______enables us to see in dimlight. (cones /
(cerebrospinal fluid) is present in between the
rods)
meninges. It acts as a shock absorber.
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

208. What is meant by power of accommodation ? In brain, outer portion contains cyton which gives
Name the muscles of the eye responsible for the a grayish colour hence called as gray matter,
same. while axon is inside.
In spinal cord, cyton is inside forming gray matter
Ans : MAIN 2005
and axon is outside forming white matter.
Ability of eye to see objects equally clear from
various distance. Ciliary muscles. 213. Answer briefly :
(i) What is meant by reflex action ?
209. Define Synapse. (ii) State simple, conditioned reflexes or none for
Ans : SQP 2002 the following :
Sneezing, blushing, contraction of pupil, lifting
Synapse is the point of contact between terminal
up a book, knitting without looking, sudden
branches of axon of one neuron with dendrites of
application of brakes without thinking.
other neuron.
Ans : SQP 2010, 1999
210. Classify the following actions as simple reflex or
(i) Reflex action is the immediate, autonomic
conditioned reflex :
nerve mediated response to a stimulus
(i) Playing a guitar.
produced at the unconscious level without the
(ii) Removing your hand suddenly when pricked
involvement of brain for thinking.
by a thorn.
(ii) Simple, simple, simple, neither of two,
(iii) Applying sudden brakes when a dog crosses
conditioned, conditioned.
the path.
(iv) Blinking of eyelids on exposure to light. 214. Account for the following :
(v) Tying ones shoe lace. An alcoholic person walks unsteadily when drunk.
Ans : COMP 2009 Ans : COMP 2010

(i) Conditioned An alcoholic person walks unsteadly when drunk

(ii) Simple because the alcohol affects cerebellum and it
(iii) Conditioned is unable to control and coordinate muscular
(iv) Simple activities properly.
(v) Conditioned
215. Match the items given in Column A with the
211. Select the correct answer to the given statement most appropriate ones in Column B and rewrite
from the four choices given below each statement: the correct matching pairs.
(i) The dorsal root ganglion of the spinal cord
contains cell bodies of (motor, sensory, Column A Column B
intermediate, none of these) neurons. (i) Cranial nerves Conditioned reflex
(ii) The cerebral hemispheres in mammals are
(ii) Acetylcholine 12 pairs
connected by (corpus luteum, hypothalamus,
pons varolii, corpus callosum). (iii) Spinal nerves Prolactin
(iii) A point of contact between two neurons is (iv) Sneezing Neurotransmitter
termed.
18 pairs
(a) Synapsis.
(b) Neuro-motor junction. 31 pairs
(c) Synapse. Natural reflex
Ans : SQP 2009, 2000
Ans : SQP 2019
(i) Sensory
(ii) Corpus callosum Column A Column B
(iii) Synapse (i) Cranial nerves 12 pairs

212. How are the cytons and axons placed in the brain (ii) Acetylcholine Neurotransmitter
and the spinal cord ? (iii) Spinal nerves 31 pairs
Ans : MAIN 2019 (iv) Sneezing Natural reflex
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 307

Part of the brain Functions The colourless jelly that fills the space between
lens and retina of eye.
1. Cerebrum It is the seat of memory,
reasoning, thinking, 253. What are eyelids ?
perce-ption, emotions
Ans : SQP 2022
and speech.
These are two movable protective folds that cover
2. Diencephalon It acts as relay centre
the anterior surface of eyeball when closed.
for sensory impulses,
reflex centre for 254. What is the function of eyelashes ?
muscular activities.
Ans : MAIN 2013
It contains centre
for water balance, The sebaceous gland present at the base of
blood pressure, body eyelashes (hair follicles) secrete a lubricating fluid
temperature, sleep and and transport it into the follicles.
hunger.
255. What is cornea ?
3. Midbrain It relays motor impulses
from cerebral cortex to Ans : COMP 2008

pons and spinal cord The modified part of sclera that forms a
and sensory impulses transparent, fibrous outer layer of eyeball at the
from spinal cord to the anterior region.
hypothalamus.
256. What is the composition of Iris ?
4. Cerebellum It maintains posture
equilibrium and muscle Ans : SQP 2000

tone. Iris contains both circular and radial muscles

along with pigment melanin.
5. Pons It transmits impulses
from one side of 257. Which structure converts vibrations into nerve
cerebellum to the other impulses ?
side. It also controls
breathing. Ans : MAIN 2003

6. Medulla It contains centre for Organ of corti.

oblongata cardiac, respiratory and
258. What is auditory meatus ?
vasomotor activities.
It also coordinates Ans : COMP 2010

reflexes for swallowing, It is a 2.5 cm long canal leading from pinna to

coughing, sneezing and eardrum.
vomiting.
259. What is Pinna ?
250. What is aqueous humour ? Ans : MAIN 2014

Ans : MAIN 2001 The visible part of external ear made-up of

The fluid that fills the space between the cornea cartilage.
and lens of eyeball.
260. What are the various parts of the external ear ?
251. Give any two functions of aqueous humour. Ans : SQP 2019

Ans : SQP 2003 Pinna, auditory canal and tympanic membrane.

(1) Supplies nutrient to cornea and lens.
261. What is the soft, hollow, sensory structures
(2) Helps to maintain shape of eye.
present in the internal ear is called as ?
252. What is vitreous humour ? Ans : MAIN 2017

Ans : COMP 2019 The membranous labyrinth.

CH 9 : NERVOUS SYSTEM AND SENSE ORGANS
Ans : SQP 2021 Ans : COMP 2023

(a) 2 - Cerebellum
3 - (wrongly marked in the diagram) Organ Sympathetic Parasympathetic
system system
(b) Controls all voluntary action.
1. Heart increases Decreases
290. (i) Draw a well labelled diagram of a Neuron heartbeat heartbeat
showing the following parts : Perikaryon, 2. Pupil of Dilates Constricts
Dendrites, Axon, Node of Ranvier and Myelin the eye
sheath.
(ii) State the function of sensory neuron and a 3. Salivary Decreases Increases
motor neuron. gland secretion of secretion of
(iii) What is a nerve made-up of ? saliva saliva

Ans : COMP 2015

292. Draw a labelled diagram of the inner ear.
(i)
Ans : COMP 2014

The labelled diagram of the inner ear is draw

below:

(ii) Sensory Neuron : These carry sensory

impulses from sense organs to CNS.
Motor Neuron : These carry motor impulses
from CNS to effectors i.e., muscles and glands. 293. The figure below shows a diagrammatic
(iii) A nerve is formed of a bundle of nerve fibres representation of a certain phenomenon pertaining
(axons) enclosed in a tubular sheath. to nervous system.

291. During a street fight between two individuals,

mention the effects on the following organs by the
autonomous nervous system, in the table given
below : (one has been done for you as an example)

Organ Sympathetic Parasympathetic

system system
e.g., Lungs Dilates Constricts
bronchi and bronchi and
bronchioles bronchioles (i) Label the part 1 to 5.
(ii) What phenomenon does the diagram represent?
1. Heart (iii) Name the parts not shown in the diagram that
2. Pupil of should be included to complete the pathway
the eye of the phenomenon.
3. Salivary Ans : MAIN 2004
gland (i) 1. White matter
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 309

(ii) Explain how the human eye adapts itself to to any stimulus without the involvement of
bright light and dim light. brain. Two types of Reflexes are – Natural and
conditioned reflexes.
Ans : MAIN 2019

(i) Dynamic balance - semicircular canal Static 276. Why does one feel blinded for a short while on
balance - utriculus and sacculus (vestibule) coming out of a dark room ?
(ii) When a person moves from dark lighted area Ans : SQP 2009
to brightly lighted area, visual purple of rods
One feels blinded for a short while on coming out of
is bleached reducing their sensitivity and
a dark room because of the formation of iodopsin
pupil constricts to reduce the amount of light
pigment by cone cells that was disintegrated in
entering eyes. This is light adaptation.
the dark and bleaching of rhodopsin pigment of
When a person moves from brightly lighted
rod cells in light.
area to dark area, visual purple of rods
which were earlier broken due to bright light 277. Explain the term Cataract.
regenerates and pupil dilates to allow more
Ans : MAIN 2010
light to enter. This is dark adaptation.
Cataract : It is a condition in which the lens turns
271. Give scientific reason for the lnjury to medulla opaque and the vision is cut down even to total
oblongata leads to death. blindness. It can be corrected by implanting a
Ans : MAIN 2016 small plastic lens behind or in front of the iris or
surgically removing the lens and using spectacle
Injury to medulla oblongata may lead to death
with highly convex lenses.
as various vital centres such as cardiac centre,
respiratory centres etc. are located in the medulla 278. State the main function of the following :
oblongata and injury to any such centre may (i) Yellow spot
prove fatal. (ii) Vitreous humour
272. Briefly explain the term Reflex action Ans : COMP 2011

Ans : SQP 2016

(i) Bright vision of normal eye.
(ii) Maintains the shape of eyeball, protects the
Reflex action is the spontaneous, automatic and retina and its nerve endings.
stereotyped response to stimuli without consulting
the will power. 279. What is accommodation of the eye ?
Ans : MAIN 2010
273. Briefly explain the term Synapse.
The ability of an eye to focus on nearby and far
Ans : MAIN 2016
objects clearly is called power of accommodation.
Close proximity between the terminal arborization It is brought about by change of convexity of the
of axon of one neuron and dendrons of another lens.
neuron without any physical contact is called
synapse. 280. What is conjunctiva and what is its function ?
Ans : SQP 2018
274. Define the term Synapse. How are Cytons and
Axons of neurons placed in the Cerebrum ? The mucous epithelial membrane that lines the
eyelids is called conjunctiva. It protects the
Ans : COMP 2021
surface of the eye.
Point of contact between terminal branches of
axon of a neuron with dendrites of another neuron
separated by a fine gap. Outer part of cerebrum
consists of cyton and inner part has axon. THREE MARKS QUESTIONS
275. What is a reflex action ? Name the two types of
reflexes. 281. Kathak is an Indian classical dance which involves
a lot of spinning by the dancers. The learners of
Ans : MAIN 2021
this dance experience dizziness in the beginning
Spontaneous, involuntary and automatic response while spinning.
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

283. A teacher drew the diagram of heart on the

blackboard and told the students to copy it in
their notebooks. Mahesh couldn't see the diagram
clearly as it appeared blurred to him.
(i) Name the defect of the eye Mahesh is suffering
from.
(ii) Where is the image formed in this defect?
(iii) Mahesh consults an eye doctor and is
prescribed suitable lenses to correct the
defect. Which type of lens do his spectacles
have?
Ans : MAIN 2024

(i) Mahesh is suffering from the defect of the eye

known as myopia or nearsightedness.
(ii) In myopia, the image is formed in front of
the retina, causing distant objects to appear
blurred.
(a) Name the part of the membranous labyrinth (iii) Mahesh's spectacles has concave lenses to
responsible for this dizziness. correct the defect of myopia.
(b) Give a suitable reason for your answer.
(c) Mention the nerve that carries the impulse for 284. Give the technical term :
dizziness to the brain. (i) An eye defect in which the cornea becomes
uneven.
Ans : SQP 2025
(ii) The photosensitive pigment present in the
(a) Semicircular canals cone cells of the retina.
(b) The fluid in the semi circular canals continue (iii) The fluid present in the anterior part in front
to spin for a short time even after the dancer of the eye lens.
stops spinning. This results in dizziness
Ans : MAIN 2010
(c) Auditory nerve.
(i) Astigmatism
282. Given below is a cross section of the human eye. (ii) lodopsin
Match the structures marked (a) to (e) with their (iii) Aqueous humour
correct functions:
Example: (f) - 6. Holds the lens in position 285. Draw a labelled diagram of the inner ear. Name
the part of the inner ear that is responsible for
Cross section of Functions static balance in human beings.
Human Eye
Ans : COMP 2005
1. Protects retina
2. Regulates the size
of the pupil
3. Alters the shape of
the lens
4. Keeps the lens
moist
5. Transmits nerve
impulses to brain
6. Holds the lens in
position

Ans : SQP 2025

(a) 5 (b) 1 (c) 2 (d) 4 (e) 3

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 311

The sensory cells in ear which are located in (ii) Arrows indicate the direction of the impulse
maculae of vestibule are responsible for static from receptor in the skin to spinal cord and
balance in human beings. then to the effector or muscle. Pathway
indicated is termed as Reflex action.
286. State briefly : (iii) Spinal nerve.
(i) Myopia (symptom and cause)
(ii) Tympanum (location and function) 288.
(iii) Yellow spot (location and importance)
Ans : SQP 1997, 1995

(i) Symptom : Near vision clear while distinct

vision blurred.
Cause : Image of distant objects are formed in
front of retina because of eyeball becomes too
long or when eye lens is too convex and hence
focal length is shortened.
(ii) Location : Between external and middle ear.
Function : Sound waves from outside cause
tympanum to vibrate which are ultimately
I. What handicaps would result from :
transmitted across the middle ear and
(i) damage to part numbered 3 ?
produce sound.
(ii) damage to part numbered 4 ?
(iii) Location : At the back of eye almost at the
II. Mention one main function of each of the
centre of the horizontal axis of the eyeball.
parts numbered 1, 2 and 5.
Importance : Place of best focus of the rays of
light that enter so a very clear image is seen Ans : SQP 2014

in the normal eye. I. (i) Visual sensation can be affected.

(ii) An individual can lose the balance of
287. The diagram given below represents the spinal
the body and coordination of muscular
cord of a mammal seen in a transverse section
activities.
together with the nerves. Study the same and
II. 1 " It is concerned with the thinking.
then answer the following questions:
2 " Memory and intelligence.
(i) Label the parts 1- 8 indicated by guidelines.
5 " Medulla oblongata controls heartbeat,
respiration and blood pressure.

289. The diagram given below is that of a human

brain. Answer the questions that follow :

(ii) What do the arrows indicate ? What is the

pathway indicated termed ?
(iii) What type of nerve is shown in the diagram.
Ans : SQP 1997

(i) 1. White matter,

2 Gray matter,
3. Dorsal root,
4. Ventral root,
5. Dorsal ganglion, (a) Label the parts numbered 2 and 3.
6. Sensory neuron, (b) State any one function of the part numbered
7. Spinal/ Motor nerve, 1.
8. Synapse.
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CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

I. Label the parts 1 to 10 which the guidelines

point.
II. Which structure :
(i) Converts sound waves into mechanical
vibrations ?
(ii) Converts vibrations into nerve impulses ?
(iii) Responds to change in position ?
(iv) Transmits impulses to the brain ?
(v) Equalizes atmospheric pressure and
pressure in the ear ?
Ans : COMP 1999

(i) Name the parts labelled A, B and C in the I. 1. Cochlea

diagram. 2. Auditory nerve
(ii) State the main functions of the parts labelled 3. Semi-circular canals
A and B. 4. Ear ossicles
(iii) What are the structural and functional units 5. Auditory canal
of the brain ? How are the parts of these units
6 Pinna
arranged in A and C ?
7. Ear drum
(iv) Mention the collective term for the membranes
covering the brain. 8. Oval window or fenestra ovalis.
(v) What is the function of Cerebrospinal fluid ? 9. Eustachian tube
10. Malleus or hammer
Ans : MAIN 2017
II. (i) Ear drum.
(i) A. Cerebrum (ii) Cochlea.
B. Cerebellum
(iii) Semi-circular canals.
C. Spinal cord
(ii) A – It is the seat of memory, will power, (iv) Auditory nerve.
emotions, experience, intelligence and controls (v) Eustachian tube.
all voluntary actions of the body.
306. The diagram given below refers to the vertical
B – Maintains balance of the body.
section of the eye of a mammal. Label the parts 1
(iii) Neuron/Nerve cell.
to 10 to which the guidelines point.
In A gray matter is outside and white matter
is inside while in C gray matter is inside and
white matter is outside.
(iv) Meninges.
(v) It serves as shock absorbing medium. Protects
brain and the rest of CNS against jerk and
jolts. It maintains constant pressure in and
around the brain.

305. The given diagram refers to the ear of a mammal.

Ans : SQP 2011

1. Aqueous humour, 2. Lens, 3. Iris, 4. Cornea, 5.

Conjunctiva, 6. Sclera, 7. Choroid, 8. Retina, 9.
Yellow spot, 10. Optive nerve.

307. The diagram below represents the structure found

in the inner ear. Study the same and then answer
the questions that follow :
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 313

2. Dorsal root FIVE MARKS QUESTIONS

3. Spinal cord
4. Ventral root
5. Gray matter 296. Draw a labelled diagram of the front-view of the
(ii) Reflex arc human eye.
(iii) Receptor and effector must be shown.
Ans : COMP 1990

294. At the start of a race, athletes react to a starter

gun. This reaction involves a number of events.
(a) In the box below, put the following events in
correct order. The first one has been done for
you.
1. Co-ordination by brain
2. Detection by receptors
3. Stimulus
4. Response
5. Effector change
3
(b) Write one difference between voluntary and
reflex action.
(c) Why are reflex actions so important to living
beings ?
Ans : MAIN 2019 297. The diagram shows a section of the human brain.
Answer the questions that follow :
(a) (i) Name the parts labelled A, B and C.
3 2 1 5 4 (ii) Give the main function of each of the parts A,
(b) Reflex actions are faster while voluntary B and C.
actions are slower. (iii) Name the three protective membranes
covering the brain.
(c) Because fast reactions help to survive from
(iv) Name the basic unit of the brain.
predators.

295. Study the diagram given below and answer the

questions that follow :

(a) Identify the defect of the eye by mentioning

the technical term.
(b) Mention one reason for this defect. Ans : SQP 2009

(c) Name the type of lens used to correct this (i) A " Cerebrum B " Cerebellum C " Pons
defect. varolii
Ans : Sem II, 2021
(ii) A " Seat of intelligence, consciousness and
will power.
(a) Hypermetropia/Hyperopia B " Maintains balance or equilibrium and
(b) Eyeball shortened from front to back co-ordinate muscular activities.
(c) Convex lens C " Carries impulses from one hemisphere of
cerebellum to other and co-ordinates muscular
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

2. How does the autonomic nervous system 319. Anita is learning to play the piano and realizes
control heart rate? that after enough practice, her fingers move
3. What role does the parasympathetic system automatically across the keys. Her teacher
play after stress? explained that this is a result of her brain
4. How can Vikram manage his anxiety? coordinating voluntary muscle movements over
Ans : time, turning them into near-automatic responses.
1. What is the difference between voluntary and
1. The sympathetic nervous system increases involuntary movements?
heart rate and prepares the body for action. 2. How does the brain control voluntary muscle
2. The autonomic nervous system controls movements?
involuntary functions like heart rate. 3. How do repeated actions become automatic?
3. The parasympathetic system slows the heart 4. Why are muscle movements important in
rate and helps the body relax. learning new skills?
4. Vikram can manage anxiety through
breathing exercises and relaxation techniques. Ans :
1. Voluntary movements are controlled by
317. Rina accidentally touches a hot pan and
will, while involuntary movements happen
immediately pulls her hand away. Her doctor
automatically.
explains that this is an example of a reflex action,
2. The brain sends signals to muscles to control
which is an automatic response to protect the
voluntary movements.
body from harm.
3. Repeated actions are stored in memory,
1. What is a reflex action?
making them automatic over time.
2. Why is Rina’s reaction automatic?
4. Muscle movements are crucial for learning
3. What part of the nervous system controls
motor skills like playing the piano.
reflexes?
4. Why are reflex actions important for safety? www.nodia.in
Ans :
1. A reflex action is an involuntary response to
a stimulus.
2. Rina’s reaction is automatic because reflexes
bypass the brain.
3. The spinal cord controls reflexes.
4. Reflex actions protect the body from
immediate harm by responding quickly.

318. Mohan has been experiencing difficulty hearing,

particularly when there is background noise.
His doctor identified a problem with the cochlea
in his inner ear, which is not processing sound
vibrations correctly.
1. What role does the cochlea play in hearing?
2. Why might Mohan have difficulty hearing in
noisy environments?
3. What part of the ear processes sound vibrations?
4. How can inner ear issues affect hearing?
Ans :
1. The cochlea converts sound vibrations into
nerve signals for the brain.
2. A damaged cochlea can make it hard to
differentiate sounds in noisy environments.
3. The inner ear processes sound vibrations.
4. Inner ear issues can reduce the clarity and
sharpness of hearing.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 315

(i) Name the phenomenon that is depicted in the (3) Lens

diagram. Define the phenomenon. (4) Pupil
(ii) Give the technical term for the point of (iv) Concave lens is used to correct this eye defect.
contact between the two nerve cells. (v)
(iii) Name the parts numbered 1, 2 and 3.
(iv) How does the arrangement of neurons in the
spinal cord differ from that of the brain ?
(v) Mention two ways by which the spinal cord is
protected in our body.
Ans : MAIN 2018

(i) Reflex action is a spontaneous, involuntary A concave lens diverges the light rays as a result,
and automatic response to any stimulus the image is now formed on the retina.
without the involvement of brain.
(ii) Synapse 303. The diagram given below represents a defect of
(iii) 1. Sensory neuron vision of the human eye :
2. Motor neuron (i) Name the defect.
3. Gray matter (ii) What is the effect of this defect on man ?
(iv) In brain, gray matter is outside and white (iii) Mention two causes for the defect.
matter is inside. (iv) How can this defect be rectified ?
In spinal cord, gray matter is inside and white (v) Draw a neat labelled diagram to show how
matter is outside this defect can be rectified.
(v) Meninges and Vertebral column. (vi) What is the nature of this image that falls on
the retina of a normal eye ?
302. Given below is a diagram depicting a defect of the
human eye. Study the same and then answer the
questions that follow :

Ans : MAIN 2004

(i) Hypermetropia.
(ii) The person cannot see near objects, i.e., only
distant objects can be viewed.
(iii) (1) The lens is flattened.
(i) Name the defect shown in the diagram.
(2) The eye ball is shortened from front to
(ii) Give two possible reasons for this defect of
back.
the eye in human beings.
(iv) This defect can be rectified by biconvex lens.
(iii) Name the parts labelled 1 to 4.
(iv) Name the type of lens used to correct this eye
defect.
(v) Draw a labelled diagram to show how the
above mentioned defect is rectified using the
lens named above.
Ans : COMP 2004

(i) Myopia.
(v) The image that fall on the retina of a normal
(ii) Two possible reasons for Myopia are :
eye is inverted, real and diminished.
(a) eyeball is lengthened from front to back.
(b) lens is too curved. 304. The diagram given below is an external view of
(iii) (1) Vitreous humour the human brain. Study the same and answer the
(2) Yellow spot questions that follow :
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

262. Name the central hole of the iris through which (i) Static equilibrium?
light enters the eye. (ii) Dynamic equilibrium?
Ans : SQP 2009 Ans : MAIN 2024

Pupil (i) Static Equilibrium: This is maintained by the

utricle and saccule, which are parts of the
263. What are the two main defects of eye ? vestibule in the inner ear.
Ans : COMP 2016 (ii) Dynamic Equilibrium: This is maintained by
the semicircular canals, also located in the
Myopia and hypermetropia.
inner ear.
264. What is organ of corti ?
268. Draw a labelled diagram of a myelinated neuron.
Ans : SQP 2022
Ans : COMP 2005
It is an elongated spiral structure that runs
A myelinated neuron
through the entire length of cochlea.

265. What is lens ?

Ans : MAIN 2007

It is a crystalline, transparent, biconvex body

held by fibres called suspensory ligament that
support it.

TWO MARKS QUESTIONS

266. Chris was watching the display of fireworks in the

sky.

269. Draw a neat diagram of a Neuron and lable any

two parts.
Ans : COMP 2021

(a) Trace the path of the light rays using the

following terms:
Fovea, Lens, Conjunctiva, Pupil, Cornea
(b) Name the nerve that carries the impulse for
vision to the brain.
Ans : SQP 2025

(a) Conjunctiva, Cornea, Pupil, Lens, Fovea

(b) Optic nerve. 270. Answer the following questions briefly :
(i) Which part of the human ear gives ‘Dynamic
267. Which parts of the ear are responsible for
balance’ and ‘Static balance’ to the body ?
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 317

(i) Myopia/short sightedness

(ii) 1 " Vitreous humour
2 " Yellow spot / fovea centralis
3 " Optic nerve
(iii) (1) Lens become too curved
(2) Eyeball lengthened from front to back.
(iv)

(i) Name the parts labelled A, B, C and D.

(ii) Name the part of the ear responsible for
transmitting impulses to the brain.
(iii) Name the part labelled above which is
responsible for :
1. Static equilibrium
2. Dynamic equilibrium 309. Draw a diagram of the human eye as seen in a
3. Hearing vertical section and label the parts which suits the
(iv) Name the audio receptor cells which pick up following descriptions relating to the :
vibrations. (i) photosensitive layer of the eye.
(v) Name the fluid present in the inner ear. (ii) structure which is responsible for holding the
Ans : COMP 2009 eye lens in its position.
(iii) structure which maintains the shape of the
(i) A " Semi circular canal
eye ball and the area of no vision.
B " Utriculus
(iv) anterior chamber seen in front of the eye lens.
C " Sacculus
(v) outer most transparent layer seen in front of
D " Cochlea
the eye ball.
(ii) Cochlea
(iii) (1) Utriculus and sacculus Ans : MAIN 2013
(2) Semi circular canal
(3) Cochlea
(iv) Sensory hair cells of organ of corti.
(v) Perilymph and endolymph.

308. Given is a diagram depicting a defect of the

human eye. Study the same and then answer the
questions that follow :

310. Given below is a diagram depicting a defect of the

human eye, study the same and then answer the
questions that follow :

(i) Name the defect show in the diagram

(ii) Name the parts labelled 1, 2 and 3.
(iii) Give two possible reasons for this eye defect.
(iv) Draw a labelled diagram to show how the
above mentioned defect is rectified.
Ans : SQP 2009
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

movements on both sides of the body. (i) Membranous labyrinth which consists of :
(iii) The three protective membranes are Piamater, (a) Semicircular ducts
Arachnoid membrance and duramater. (b) Vestibule
(iv) The basic unit of the brain is neuron/nerve (c) Cochlear duct
cell. (ii) Three bones are malleus, incus and stapes, its
biological term is ear ossicles.
298. Given is the diagram of a part of the human ear. (iii) 1. Maculae
Study the same and then answer the questions 2. Organs of corti
that follow : 3. Cristae present in the ampullae of
semicircular ducts.
(iv) Auditory nerve.

300. The diagram given below represents the cross-

section of the human eye :

(i) Give the biological term for Malleus, Incus

and Stapes.
(ii) Name the parts labelled A, B and C in the
diagram.
(iii) State the functions of the parts labelled ‘A’
and ‘B’ (i) Name the parts labelled 1 to 12.
(iv) Name the audio receptor region present in the (ii) What is the function of the part marked ‘10’ ?
part labelled ‘A’. (iii) What would happen if part ‘5’ is damaged or
cut ?
Ans : SQP 2003
Ans : SQP 2000, 1996
(i) Ear Ossicles.
(ii) (A) Cochlea, (i) (1) Sclerotic, (2) Choroid, (3) Retina, (4)
(B) Semi-circular canals, Yellow spot, (5) Optic nerve, (6) Blind spot,
(C) Vestibular apparatus. (7) Lens, (8) Aqueous humour, (9) Pupil (10)
(iii) (A) Hearing Iris, (11) Vitreous humour, (12) Cornea.
(B) Dynamic balancing. (ii) It regulates the light entering the eye to avoid
(iv) Organ of Corti. damage to the cells of the retina.
(iii) If ‘5’ is damaged or cut, a person would not
299. With reference to the human ear, answer the be able to see because the sensation would
questions that follow : not reach the human brain.
(i) Give the technical term for the structure
found in the inner ear. 301. The diagram given below shows the internal
(ii) Name the three small bones present in the structure of a spinal cord depicting a phenomenon.
middle ear. What is the biological term for Study the diagram and answer the questions :
them collectively ?
(iii) Name the part of the ear associated with
(1) static balance (2) hearing (3) dynamic
balance.
(iv) Name the nerve, which transmits messages
from the ear to the brain.
Ans : COMP 2011
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 319

313. The diagram represents human brain as seen in a Ans : MAIN 1996

external view. (i) 1. Stapes, 2. Semi-circular canals, 3. Auditory

(i) Name the parts 1, 2, 3 and 4. nerve, 4. Cochlea, 5. Eustachian tube, 6. Ear-
drum or Tympanum 7. Malleus, 8. Pinna.
(ii) Function of Part 2 - It brings about the
dynamic equilibrium which helps in the
maintenance of body position in response to
movement.
Function of Part 7 - The hammer or Malleus
is fastened to the ear-drum whose vibrations
are transmitted through these three bones
(malleus, incus and stapes) to the membrane
across the oval window. These small bones
act as levers and also serve to increase the
magnitude or power of vibrations.
(iii) The pin or any sharp object may injure the
(ii) Mention the difference in the arrangement of
eardrum. So it is harmful and should be
the nerve cells in parts marked 1 and 4.
avoided altogether while removing the wax
(iii) What is the main function of parts marked 3
from the ear.
and 4 ?
(iv) Name the sheet of nerve fibres that connects
the two halves of the part labelled 1.
Ans : SQP 2018 CASE BASED QUESTION
(i) 1. Cerebrum
2. Cerebellum
3. Medulla oblongata 315. Aditi, a 14-year-old, struggles with blurry vision
4. Spinal cord when looking at distant objects. Her doctor
(ii) 1 – Cytons outside and axons inside explained that her eye’s lens is too curved, which
2 – Axons outside and cytons inside leads to the image forming in front of the retina,
(iii) 1 – Controls involuntary reflexes like a condition known as myopia.
respiration and circulation. 1. What causes blurry vision in myopia?
2 – Mediates reflex actions 2. How does the lens of the eye contribute to
(iv) Corpus callosum. focusing light?
3. What is the function of the retina in vision?
314. The diagram given below represents the parts of 4. How can myopia be corrected?
the human ear : Ans :
1. Myopia occurs when the lens is too curved,
causing the image to form in front of the
retina.
2. The lens focuses light onto the retina to create
a clear image.
3. The retina converts light into nerve signals
for the brain to process.
4. Myopia is corrected with concave lenses,
which help focus light on the retina.

316. Vikram feels anxious during exams, causing his

heart to race. His doctor mentioned that his
(i) Name the parts labelled 1 to 8. sympathetic nervous system is responsible for this
(ii) What is the function of the parts marked 2 ‘fight or flight’ response, which increases his heart
and 7? rate.
(iii) Why is it harmful to use a pin or any sharp 1. What does the sympathetic nervous system
object to remove the wax from the ear ? do in stressful situations?
CH 9 : NERVOUS SYSTEM AND SENSE ORGANS

(i) Name the defect shown in the diagram. Ans : COMP 2021

(ii) What are the two possible reasons that cause (i) 1. Dendrite
this defect? 2. Nissl’s granule
(iii) Name the type of lens used to correct this 3. Nucleus
defect. 4. Axon
(iv) With the help of a diagram show how the 5. Neurilemma
defect shown above is rectified using a suitable 6. Myelin sheath
lens. 7. Node of Ranvier
Ans : COMP 2016
(ii) 4 (Axon) - Helps in transmission of nerve
impulse from cyton to axon endings.
(i) Myopia/Near-sightedness 7 (Node of Ranvier) - Provides mechanical
(ii) Excessive thickening of cornea and increase in support to the structure of neuron.
the length of eye ball from front to back. (iii) Synapse
(iii) Concave lens (iv) Impulse is a wave of electrical disturbance on
(iv) the surface of axon.

312. The diagram below is that of a human brain.

Study the diagram carefully and then answer the
questions that follow :
(i) Label the parts numbered 1 to 5.

311. The diagram shows a neuron. Study the diagram (ii) What handicaps would result from :
and then answer the questions that follow : (a) Damage to part numbered 3 ?
(b) Damage to part numbered 4 ?
(iii) What are the functions of parts numbered 1,
2 and 5 ?
Ans : MAIN 2014

(i) 1. frontal lobe of cerebrum

2. temporal lobe of cerebellum
3. occipital lobe of cerebrum
4. cerebellum
5. medulla oblongata
(ii) (a) It will result in failure of vision.
(b) Person would not be able to maintain
body balance, posture and muscular co-
ordination would be lost.
(i) Label the parts 1 to 7.
(iii) Part number 1 is the seat of intelligence,
(ii) State the function of part 4 and 7.
memory and centre of voluntary activities.
(iii) What is the name given to the junction
Part number 2 controls the hearing.
between two neurons?
Part number 5 controls and regulates cardiac
(iv) Define impulse.
and vascomotor activities.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 321

CHAPTER 10
THE ENDOCRINE SYSTEM

takes place at proper time and in a correct

SUMMARY sequence.
The hormones are secretions from specific cells
or glands in the body and are carried to all parts
1. ENDOCRINE SYSTEM
by blood.
Endocrine glands control, communicate,
coordinate and integrate various functions of 1.1 Chemical Nature of Hormones
all body organs by secretion of hormones and Hormones are organic compounds of diverse
collectively constitute the endocrine system. The nature. Chemically hormones may be
science concerned with the structure of endocrine proteinaceous (FSH, LH, TSH, etc), peptides
glands, diagnosis and treatment of disorders of (ACTH, oxytocin, vasopressin, etc.), steroids (sex
endocrine glands is known as endocrinology. hormones) or amino acid derivatives (thyroxine,
Thomas Edison is called as Father of endocrinology. epinephrine, etc.).
Secretin was the first hormone to be discovered by
William M Bayliss and Ernest H Starling and the 1.2 Endocrine Glands in Humans
name hormone was coined by Starling. The mammalian endocrine system consists of the
In human body, there are two types of glands following endocrine glands :
– exocrine (gland with duct) and endocrine 1. Pituitary gland – associated with brain.
(ductless gland). 2. Thyroid gland – associated with pharynx
Endocrine (ductless) glands are such glands which (neck).
secrete hormones which are extremely important 3. Adrenal gland – associated with kidneys.
for regulation of body activities. The hormones 4. Pancreas – associated with liver.
are released directly into the blood stream as Various endocrine glands, their location,
there are no ducts in endocrine glands hence hormones, functions and disorders of hypo and
called ductless gland. hypersecretion are given below in the table :
The activities in our body are highly complex and
they need to be so regulated that every activity

Gland and location Hormones and their nature Functions Dis-orders

1. Pitultary Gland Anterior Lobe Stimulates spermato-
(attached to the (i) (FSH) Follicle- genesis in male,
hypothalamus of stimulating hormone growth of ovarian
brain) (Protein) follicle in female,
induces testosterone
secretion in male.
(ii) Luteinising Ovulation and
Hormone(LH) (Protein) secretion of estrogen
and progesterone in
female.
CH 10 : THE ENDOCRINE SYSTEM

(iii) Somatotropin Regulates protein Deficiency causes

(Protein) metabolism and dwarfism, excess
growth of bones. produces gigantism in
young and acromegaly
in adults.
(iv) Prolactin (Protein) Controls development
of milk glands.
(v) Adreno-corticotropin Stimulates secretion
(ACTH) (Peptide). of hormones of
adrenal cortex.
(vi) Thyotropin (TSH) Stimulates secretion
(Protein) of thyroid hormones.
Middle lobe
(i) Melanocyte Stimulating Controls skin colour.
Hormone (MSH) (Peptide)
Posterior lobe
(i) Oxytocin (Peptide) Regulates uterine
contractions and
release of milk.
(ii) Vaso-pressin (Peptide) Reduces loss of water
in urine.
2. Thyroid (in the (i) Thyroxine (lodinated Regulates oxidation Deficiency causes
neck on the sides of amino acid) of food, controls diabetes insipidus.
trachea just below basal metabolic rate,
the larynx) differentiation and Hyposecretion causes
metamor-phosis. cretinism in children
Myxedema in adults.
(ii) Calcitonin (Peptide) Controls calcium and Iodine deficiency causes
phosphorus balance simple goitre.
in the blood plasma.
Hypers-ecretion causes.
Grave’s disease or
exophthal-mic goitre.
3. Adrenal (attached Cortex Regulates Its deficiency causes
with the kidneys) (i) Gluco-corticoids, e.g. carbohydrate, fat and Addison’s diseases,
Cortisol and cortico- protein metabolism. excess causes Cushing’s
sterone (stedoid) syndrome, Aldoster-
onism.
(ii) Mineralo-corticoids, Controls salt and
e.g. Aldosterone (steroid) water metabolism.
(iii) Sex corticoids Produce accessory Excess in early life
(steroids) e.g. Adrenal sex characters. causes early abnormal
androgen. sexual maturity.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 323

Medulla Whip up metabolism

(i) Adrenaline (Amine) in emergency by
increasing heart
(ii) Noradren-aline beat, blood pressure,
(Amine) respiratory rate,
blood sugar level, etc.
Controls
carbohydrate
metabolism.
4. Pancreases (below (i) Insulin (Protein) Release of sugar from Deficiency causes
stomach) liver. diabetes mellitus.
(ii) Glucagon (Protein) Controls nutrient
absorption into
blood.
(iii) Somatostatin Inhibitor of growth
(Protein) hormone. Insulin and
glucagon.

2. Secrete hormones. 2. Secrete enzymes

Important Differences : or other useful
(a) substances.
Nervous Control Endocrine Control 3. Their secretions 3. Their secretion
1. Works by the Works by the always act away may act away or
conduction of nerve release of chemical from the site of at the site of their
impulses. messenger the production. production.
hormones. 4. Secretions are 4. Secretions are
2. Works very rapidly. Works slowly. transported by transported by
way of blood. way of ducts.
3. Nerve Impulse is Hormones travel
conducted through through blood (c)
nerve fibres. stream.
Cretinism Myxedema
4. Effects of nerve It has prolonged
impulses are short effect. 1. Caused by 1. Caused by
lived. hyposecretion hyposecretion of
of thyroxine in thyroxine in adults.
5. Information is Information spreads
infants.
directed to specific throughout the
part. body by blood 2. It is 2. It is characterised
stream. characterised by puffy
by stunted appearance due
6. It has no effect on Affects growth.
growth, pot to accumulation
growth.
belly, protruding of fat in the
7. Does not influence It brings tongue and subcutaneous
chemical changes about specific pigeon chest. tissue and oedema.
and cannot regulate chemical changes
metabolism. and regulate 3. Mental 3. Mental and sexual
metabolism. and sexual development is
retardation take not affected but
(b) place. patients lack
alertness.
Endocrine Gland Exocrine Gland
1. Ductless glands. 1. Glands with ducts.
CH 10 : THE ENDOCRINE SYSTEM

(d) Ans : MAIN 2013

A gland that both hormone and enzyme is the

Gigantism Acromegaly pancreas.
1. Caused by 1. Caused by Thus (b) is correct option.
oversecretion of oversecretion of
somatotropin somatotropin after 4. Gigantism and Acromegaly are due to :
from childhood. adolescence. (a) Hyposecretion of Thyroxine.
(b) Hyposecretion of Growth hormone
2. Due to abnormal 2. Abnormal increase
(c) Hypersecretion of Thyroxine
elongation of long bones of
of bones and hand and legs; (d) Hypersecretion of Growth hormone
muscles person person has gorilla Ans : SEM I, 2021
is of abnormally like appearance
Growth hormones are secreted by the anterior
large height. but is not a giant.
lobe of the pituitary gland under the influence
of GH- releasing hormone. Hypersecretion of
growth hormones causes excessive growth. In
children, overproduction causes gigantism while
MULTIPLE CHOICE QUESTION in adults it causes acromegaly. Growth hormone
stimulates the growth of bones muscles and many
1. Priya tried to match the hormones with their internal organs and overproduction can lead to
effect on the human body. She tabulated the pairs the abnormal growth of all such tissue.
as follows: Thus (d) is correct option.

Hormone Effect on the body 5. Gigantism and Acromegaly are due to :

(a) Hypersecretion of Growth hormone
P Stimulates conversion of Glycogen
(b) Hypersecretion of Thyroxine
to Glucose
(c) Hyposecretion of Growth hormone
Q Reabsorption of water by the (d) Hyposecretion of Thyroxine
Nephrons.
Ans : SEM II, 2021
Identify the correct pair of hormones.
(a) P — Insulin, Q — Glucagon. Growth hormones are secreted by the anterior
(b) P — Adrenaline, Q — Oxytocin. lobe of the pituitary gland under the influence
(c) P — Glucagon, Q — Vasopressin. of GH- releasing hormone.Hypersecretion of
(d) P — Vasopressin, Q — Adrenaline. growth hormones causes excessive growth.In
children, overproduction causes gigantism while
Ans : SQP 2025
in adults it causes acromegaly. Growth hormone
Thus (c) is correct option. stimulates the growth of bones muscles and many
internal organs and overproduction can lead to
2. The hormone that affects urination is: the abnormal growth of all such tissue.
(a) Adrenaline (b) Vasopressin Thus (c) is correct option.
(c) Oestrogen (d) Thyroxine
Ans : MAIN 2024
6. Gigantism and acromegaly are due to
(a) hyposecretion of thyroxine
Vasopressin, also known as antidiuretic hormone (b) hyposecretion of growth hormone
(ADH), plays a crucial role in regulating water (c) hypersecretion of thyroxine
balance and urine concentration in the body. (d) hypersecretion of growth hormone
Deficiency of ADH causes diabetes insipidus In
which urination is frequent and copius. Ans : COMP 2018

Thus (b) is correct option. Acromegaly and gigantism are disorders of growth
hormone hypersecretion. The most common cause
3. A gland which secretes both hormone and enzyme is a growth hormone (GH) secreting adenoma in
is the : the pituitary gland.
(a) Pituitary (b) Pancreas Thus (d) is correct option.
(c) Thyroid (d) Adrenal
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 325

7. Oxytocin is secreted by 10. Diabetes insipidus is due to failure of secretion of

(a) Posterior lobe of pituitary (a) Insulin
(b) Hypothalamus (b) Aldosterone
(c) Anterior lobe of pituitary (c) ADH
(d) Middle lobe of pituitary (d) Thyroid
Ans : MAIN 2010 Ans : SQP 2019

Oxytocin is secreted by paraventricular nuclei Diabetes insipidus is due to the hyposecretion or

cells of the hypothalamus and transported failure of secretion of antidiuretic hormone (ADH)
through axons to the posterior lobe of the secreted by the posterior pituitary.
pituitary. Neurohypophysis (posterior pituitary) Thus (c) is correct option.
is a storage -releaser center for the hormone
synthesis by the hypothalamus. Oxytocin acts on 11. The deficiency of ADH causes :
the smooth muscles of the body and stimulates (a) Diabetes insipidus
their concentration i.e. during childbirth oxytocin (b) Diabetes mallitus
causes contraction of uterine muscles. Oxytocin (c) Dwarfism
also helps in milk ejection from the ducts in the (d) Acromegaly
breast to the nipples. Ans : COMP 2020
Thus (a) is correct option.
Diabetes insipidus is caused by a lack of antidiuretic
8. Antidiuretic hormone ADH is produced from hormone (ADH), also called vasopressin, which
(a) Kidney prevents dehydration, or the kidney's inability to
(b) Hypothalamus respond to ADH. ADH enables the kidneys to
(c) Posterior pituitary retain water in the body. The hormone is produced
(d) Anterior pituitary in a region of the brain called the hypothalamus.
Thus (a) is correct option.
Ans : SQP 2011

Antidiuretic hormone (ADH) is synthesized by 12. Which of the following is secreted by the pituitary?
hypothalamic neurons and stored in the posterior (a) TSH releasing hormone
pituitary in form of Herring bodies. ADH has also (b) ACTH releasing hormone
called vasopressin or arginine vasopressin and it (c) Thyroxin
acts on renal tubules of nephrons in the kidney (d) TSH
resulting in conditional reabsorption of water. Ans : SQP 2015
The posterior pituitary (neurohypophysis)
The pituitary gland is a bilobed gland situated
produces antidiuretic hormone when we intake
just below the hypothalamus in the brain.
less fluid so as to maintain osmotic concentration
This gland secretes growth hormone, thyroid
in blood. The posterior pituitary is also called
stimulating hormone, adrenocorticotrophic
Pars nervosa.
hormone, luteinizing hormone, gonadotropic
Thus (c) is correct option.
hormone, prolactin.
9. A gland having endocrine as well as exocrine Thus (d) is correct option.
function is
13. Gigantism and dwarfism are the diseases related
(a) Pituitary
to
(b) Thyroid
(a) Prolactin hormone of mammary gland
(c) Adrenal
(b) Growth hormone of adenohypophysis
(d) Pancreas
(c) Luteinising hormone of pituitary gland
Ans : MAIN 2004 (d) Thyroid stimulating hormone of thyroid gland
The pancreas has both an endocrine and an Ans : MAIN 2011
exocrine function. The exocrine pancreas assists
Gigantism and dwarfism are caused by
in food digestion by releasing a secretion rich in
abnormalities in the secretion of the growth
bicarbonate, which helps to neutralize the acidic
hormone (somatotropin), which is produced by the
environment created in the stomach.
adenohypophysis (anterior pituitary). Excessive
Thus (d) is correct option.
secretion during childhood leads to gigantism,
CH 10 : THE ENDOCRINE SYSTEM

Lata said: Glucagon and oxytocin. 41. A teacher asked her students to name two
Abhay said: Somatostatin and insulin. examples of vestigial organs in the human body.
Who were correct? - Raj said: Wisdom teeth and tailbone.- Sonu said:
(a) Raj and Abhay. Ear muscles and appendix.- Lata said: Tailbone
(b) Sonu and Lata. and appendix.- Abhay said: Wisdom teeth and
(c) Raj and Sonu. nails.
(d) Abhay and Lata. Who were correct?
(a) Raj and Lata.
Ans : COMP 2000
(b) Sonu and Lata.
Insulin, glucagon, and somatostatin are hormones (c) Raj and Sonu.
secreted by the pancreas. Adrenaline is secreted (d) Abhay and Raj.
by the adrenal gland, and oxytocin is secreted by
the pituitary gland. Ans : SQP 2019

Thus (a) is the correct option. Wisdom teeth, tail-bone, and appendix are
vestigial organs. Ear muscles are vestigial, but
39. A teacher asked her students to name two organs nails are not vestigial; they serve an active
involved in excretion in the human body. function.
Raj said: Kidneys and skin. Thus (a) is the correct option.
Sonu said: Lungs and heart.
Lata said: Skin and liver.
Abhay said: Kidneys and lungs.
Who were correct?
(a) Raj and Abhay.
ONE MARK QUESTIONS
(b) Sonu and Lata.
(c) Lata and Sonu.
(d) Raj and Lata. DIRECTION : Give the category and select the odd
one out.
Ans : MAIN 2005

Kidneys and lungs are involved in excretion. 42. Goitre, dwarfism, acromegaly, cataract.
Kidneys filter waste from the blood, and the
lungs excrete carbon dioxide. Skin is involved in Ans : MAIN 2006

excretion of sweat, but the liver and heart are not Hormonal diseases – Cataract
excretory organs.
Thus (a) is the correct option. 43. ADH, TSH, NADP, ACTH
Ans : COMP 2006
40. A teacher asked her students to list two functions
of the liver. Hormones – NADP
Raj said: Detoxification and bile production.-
44. Steroids, cortisone, testosterone, adrenaline,
Sonu said: Blood sugar regulation and digestion
prolactin.
of proteins.
Lata said: Production of bile and detoxification.- Ans : SQP 2004
Abhay said: Detoxification and urea production. Hormones – Steroids
Who were correct?
(a) Raj and Lata. 45. Adrenal, liver, thyroid, pituitary
(b) Sonu and Abhay.
Ans : MAIN 2003
(c) Raj and Abhay.
(d) Sonu and Lata. Endocrine glands – Liver

Ans : COMP 2016 46. Adrenaline, penicillin, insulin, thyroxine

The liver detoxifies harmful substances and Ans : SQP 2002
produces bile. It helps regulate blood sugar, but it
Hormones – Penicillin
does not directly digest proteins or produce urea
(which is produced by the kidneys). 47. Vasopressin, Growth hormone, TSH, ACTH,
Thus (c) is the correct option. FSH.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 327

21. Which of the following glands is known as master (a) Adrenal cortex
gland? (b) Pituitary
(a) Adrenal glands (c) Thyroid
(b) Kidneys (d) Adrenal medulla
(c) Pancreas
Ans : COMP 2009
(d) Pituitary
Cushing’s disease is caused by the oversecretion of
Ans : MAIN 2000
cortisol from the adrenal cortex. This happens due
The pituitary gland is sometimes called the to excessive ACTH secretion from the pituitary,
"master" gland of the endocrine system because leading to elevated cortisol levels. Symptoms
it controls the functions of many of the other include weight gain, high blood pressure, and
endocrine glands. The pituitary gland is no larger fatigue.
than a pea, and is located at the base of the brain. Thus (a) is correct option.
Thus (d) is correct option.
25. A doctor explains to a patient with bulging eyes
22. Identify the correct statement. that this condition, called exophthalmic goitre,
(a) Hypothyroidism causes cretinism is caused by the overactivity of the thyroid
(b) Hypothyroidism causes goitre gland. Exophthalmic goitre is caused due to the
(c) Hyperthyroidism adversely affects the body overactivity of
physiology (a) Thyroid
(d) All of the above (b) Thymus
(c) Parathyroid
Ans : SQP 2004 (d) Adrenal cortex
Hypothyroidism is a condition in which the Ans : COMP 2016
thyroid gland produces or releases insufficient
Exophthalmic goitre, also known as Graves
thyroid hormones or thyroxin. Hypothyroidism
disease, is an autoimmune disease. It is a disease
occurs when the thyroid gland makes or releases
related to the thyroid gland and it is caused due
inadequate thyroid hormones or thyroxine.
to hyperthyroidism. Thyroid glands generally
Hypothyroidism is linked to simple goiter,
become enlarged and secrete high levels of thyroid
cretinism, and myxoedema. These disorders
hormones.
have a negative impact on the body's physiology
Thus (a) is correct option.
because they induce skin abnormalities, thyroid
gland enlargement, and other symptoms. 26. A patient visits a doctor with symptoms of
Thus (d) is correct option. abnormal bone growth. The doctor explains that
such conditions, like gigantism in children and
23. Which of the following is produced from adrenal
acromegaly in adults, occur due to the excessive
cortex?
release of a hormone that regulates body growth.
(a) Aldosterone (b) Thyroxin
Gigantism and Acromegaly are due to:
(c) Adrenalin (d) Insulin
(a) Hyposecretion of Thyroxine
Ans : SQP 2002 (b) Hypersecretion of Thyroxine
The adrenal cortex produces several hormones. (c) Hyposecretion of Growth hormone
The most important are aldosterone (a (d) Hypersecretion of Growth hormone
mineralocorticoid), cortisol (a glucocorticoid), Ans : COMP 2005
and androgens and estrogen (sex hormones).
Gigantism (in children) and Acromegaly (in
Aldosterone helps the kidneys control the amount
adults) are caused by the hypersecretion of growth
of salt in the blood and tissues of the body.
hormone. In children, excess growth hormone
Thus (a) is correct option.
leads to gigantism, resulting in abnormal height
24. A patient with weight gain and high blood and size. In adults, the same condition results
pressure is diagnosed with Cushing’s disease, in acromegaly, characterized by the enlargement
caused by the over-secretion of a hormone from of bones, particularly in the hands, feet, and
the adrenal cortex. Cushing’s disease is due to face, as growth plates have already closed. Both
oversecretion of conditions are linked to the overactivity of the
CH 10 : THE ENDOCRINE SYSTEM

while deficient secretion results in dwarfism. This Ans : MAIN 2023

hormone is critical for regulating the growth and Acromegaly is a disorder which occurs due to
development of bones and tissues. hypersecretion of growth hormone after the
Thus (b) is correct option. physical development of body is complete. There
is abnormal thickening of bones and soft tissues.
14. Cretinism and myxoedema are due to The frontal bone gets enlarged and thickened
(a) Hyposecretion of thyroxine which gives a gorilla like appearance to the
(b) Hypersecretion of thyroxine person. Growth hormone is secreted from the
(c) Hypersecretion of growth hormone anterior lobe of pituitary gland which is part of
(d) Hyposecretion of growth hormone adenohypophysis.
Ans : SQP 2007 Thus (c) is correct option.
Cretinism (in children) and myxoedema (in 18. Bulging of eyes, increased BMR, high B.P. and
adults) are caused by the hyposecretion of heart rate are symptoms of
thyroxine, a hormone produced by the thyroid (a) Cretinism
gland. Thyroxine plays a key role in regulating (b) Myxedema
metabolism, growth, and development. Insufficient
(c) Exophthalmic goitre
levels of thyroxine during childhood lead to
cretinism, which results in stunted physical and (d) Goitre
mental growth. In adults, low thyroxine levels Ans : COMP 2021
cause myxoedema, characterized by weight gain,
Bulging of eyes, increased BMR, B.P. and heart
fatigue, and swelling of the skin.
rate are symptoms of Exophthalmic goitre.
Thus (a) is correct option.
Thus (c) is correct option.
15. Cretinism is due to
19. Father of Endocrinology is
(a) Deficiency of thyroid in adults
(a) Huxley
(b) Oversecretion of thyroid in children
(c) Deficiency of thyroxin in children (b) Thomas Addison
(d) Oversecretion of thyroid in adults (c) Abel
(d) Kimball and Murlin
Ans : SQP 2014

Cretinism and myxoedema are due to Ans : SQP 2015

hyposecretion of thyroxine. Thomas Addison is known as the father of

Thus (c) is correct option. endocrinology. He discovered Addison's disease
was caused by a deficiency of aldosterone from
16. Contraction of uterus during child birth is due to the adrenal cortex.
which hormone Thus (b) is correct option.
(a) TSN
(b) Glucagon 20. Cretinism, mental retardation, low intelligence
(c) Oxytocin quotient, abnormal skin, deaf-mutism, etc., are
(d) FSH the results of
(a) Hyperthyroidism
Ans : MAIN 2016
(b) Goitre
Oxytocin is a natural hormone that stimulates
(c) Hypothyroidism
uterine contractions in childbirth and lactation
(d) Both (b) and (c)
after childbirth. It also affects aspects of human
behavior and the male and female reproductive Ans : COMP 2021
systems.
Hypothyroidism or low secretion of thyroxine
Thus (c) is correct option.
is associated with three conditions, namely,
17. Acromegaly is due to over secretion of cretinism, simple goiter, and myxoedema. These
(a) GH in children conditions are further associated with mental
(b) ACTH retardation, low intelligence quotient, abnormal
(c) GH after adolescence skin, deaf-mutism.
(d) Thyroid in adults Thus (c) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 329

33. Meera tried to match hormones with their effects Ans : MAIN 2015

on the body as shown below: Oxytocin stimulates uterine contractions during

childbirth, and somatotropin (growth hormone)
Hormone Effect on the body promotes protein synthesis and overall growth.
P Increases heart rate Insulin regulates blood sugar, and TSH stimulates
Q Promotes growth of ovarian follicles the thyroid gland.
Thus (a) is correct option.
Identify the correct pair of hormones:
(a) P – Adrenaline, Q – FSH. 36. Alok tried to match hormones with their effects
(b) P – Insulin, Q – FSH. on the body as shown below:
(c) P – Adrenaline, Q – Prolactin.
Hormone Effect on the body
(d) P – Thyroxine, Q – LH.
P Stimulates metabolism and oxygen
Ans : COMP 2020
consumption
Adrenaline increases heart rate, and FSH (Follicle
Q Decreases blood sugar levels
Stimulating Hormone) promotes the growth of
ovarian follicles. Insulin regulates blood sugar, Identify the correct pair of hormones:
and prolactin stimulates milk production. (a) P – Thyroxine, Q – Insulin.
Thus (a) is correct option. (b) P – Adrenaline, Q – Glucagon.
(c) P – Thyroxine, Q – Glucagon.
34. Rahul tried to match hormones with their effects (d) P – Adrenaline, Q – Insulin.
on the body as shown below:
Ans : COMP 2016

Hormone Effect on the body Thyroxine stimulates metabolism and increases

P Promotes water retention in kidneys oxygen consumption, while insulin decreases
blood sugar levels. Glucagon raises blood sugar
Q Raises blood calcium levels
levels, and adrenaline increases heart rate and
Identify the correct pair of hormones: metabolism.
(a) P – Aldosterone, Q – Calcitonin. Thus (a) is correct option.
(b) P – Vasopressin, Q – Parathyroid hormone.
(c) P – Vasopressin, Q – Calcitonin.
DIRECTION : Conversation Type Question
(d) P – Adrenaline, Q – Parathyroid hormone.
Ans : SQP 2011 37. A teacher asked her students to give two examples
Vasopressin promotes water retention in the of enzymes involved in digestion.
kidneys, and the parathyroid hormone raises Raj said: Amylase and lipase.
blood calcium levels. Calcitonin lowers calcium Sonu said: Pepsin and insulin.
levels, while adrenaline affects heart rate and Lata said: Amylase and pepsin.
blood pressure. Abhay said: Lipase and bile.
Thus (b) is correct option. Who were correct?
(a) Raj and Lata.
35. Priya attempted to match hormones with their (b) Sonu and Lata.
effects on the body as shown below: (c) Raj and Abhay.
(d) Sonu and Abhay.
Hormone Effect on the body
Ans : SQP 2018
P Stimulates uterine contractions
Amylase, lipase, and pepsin are enzymes involved
Q Promotes protein synthesis and in digestion, while insulin and bile are not enzymes.
growth Insulin is a hormone, and bile is a digestive fluid.
Identify the correct pair of hormones: Thus (a) is the correct option.
(a) P – Oxytocin, Q – Somatotropin.
(b) P – Insulin, Q – Somatotropin. 38. A biology teacher asked her students to name two
(c) P – Vasopressin, Q – TSH. hormones secreted by the pancreas.
Raj said: Insulin and glucagon.
(d) P – Oxytocin, Q – LH.
Sonu said: Insulin and adrenaline.
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CH 10 : THE ENDOCRINE SYSTEM

growth hormone, typically from the anterior 30. In a prenatal class, the instructor explains that
pituitary gland. a specific hormone triggers uterine contractions
Thus (c) is correct option. during childbirth. Contraction of uterus during
child birth is due to which hormone
27. A doctor explains to a patient with diabetes that (a) Oxytocin
a specific type of cell in the pancreas is responsible (b) Glucagon
for producing insulin, which helps regulate blood (c) TSN
sugar levels. Insulin is secreted by (d) FSH
(a) Beta cells of pancreas
(b) Alpha cells of pancreas Ans : COMP 2017

(c) Delta cells of pancreas Oxytocin is a natural hormone that stimulates

(d) None of the above uterine contractions in childbirth and lactation
Ans : COMP 2016
after childbirth. It also affects aspects of human
behavior and the male and female reproductive
Insulin is a hormone that plays a crucial role in systems.
regulating blood sugar levels. It is secreted by Thus (a) is correct option.
the beta cells of the pancreas, specifically within
the Islets of Langerhans. When blood glucose 31. The child frightened by the loud noise, runs
levels rise, such as after eating, beta cells release quickly to his mother. Which substance helps in
insulin, which allows cells to absorb glucose from this response?
the bloodstream and use it for energy. This helps (a) Insulin
maintain normal blood sugar levels and prevents (b) Adrenaline
conditions like hyperglycemia. (c) Amylase
Thus (a) is correct option. (d) Protease

28. A biology student is learning about glands in the Ans : MAIN 2023

human body and discovers that one particular The child frightened by the loud noise runs
gland is unique because it produces both quickly to his mother. Adrenaline substance helps
hormones and enzymes, which play a crucial in this response.
role in digestion and metabolism. A gland which Thus (b) is correct option.
secretes both hormone and enzyme is
(a) Pituitary
DIRECTION : Matching Type Question
(b) Pancreas
(c) Thyroids
32. Suresh attempted to match hormones with their
(d) Adrenal
effects on the human body as shown below:
Ans : SQP 2020
Hormone Effect on the body
A gland that both hormone and enzyme is the
pancreas. P Lowers blood sugar levels
Thus (b) is correct option. Q Stimulates milk production in
females
29. A patient with diabetes visits a doctor, who
explains that a specific part of the body contains Identify the correct pair of hormones:
clusters of cells that regulate blood sugar levels (a) P – Glucagon, Q – Prolactin.
by producing hormones like insulin. Islets of (b) P – Insulin, Q – Prolactin.
Langerhans are located in : (c) P – Insulin, Q – Oxytocin.
(a) Liver (d) P – Glucagon, Q – Oxytocin.
(b) Pituitary gland Ans : MAIN 2010
(c) Spleen
(d) Pancreas Insulin lowers blood sugar levels, and prolactin
stimulates milk production. Glucagon raises
Ans : SEM II, 2021 blood sugar levels, while oxytocin regulates
Islets of Langerhans are islands of endocrine cells uterine contractions and milk ejection but not
scattered throughout the pancreas production.
Thus (d) is correct option. Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 331
Ans : COMP 2010 Ans : SQP 2001

Anterior lobe of pituitary – Vasopressin Adrenal, thyroid /pitutiary

48. Cortisone, Somatotropin, Adrenocorticotropic 58. The endocrine gland which produces emergency
hormone, Vasopressin. hormone.
Ans : MAIN 2016 Ans : SQP 1998

Cortisone, all others are secreted by the pituitary Adrenal gland.

gland.
59. The form in which glucose is stored in liver.
49. ACTH, TSH, ADH, FSH
Ans : COMP 2015
Ans : COMP 2017
Glycogen
ADH : Rest are hormones of anterior pituitary
60. Hormones which stimulates other endocrine
50. Thyroid, adrenal, pituitary, prostate glands to produce their specific hormones.
Ans : MAIN 2000 Ans : MAIN 2014, 2012

Prostate Pituitary gland hormones

51. Cretinism, myxedema, goitre, scurvy. 61. The two portions of adrenal gland.
Ans : SQP 2015 Ans : SQP 2017

Scurvy Adrenal cortex and adrenal medulla

52. Insulin, glucagons, diabetes insipidus, diabetes 62. The Master gland of the body.
mellitus.
Ans : MAIN 2023
Ans : COMP 2001
Pituitary
Diabetes insipidus
63. The cause of diabetes mellitus.
53. Addison’s disease, Cushing’s Syndrome,
Ans : COMP 2014
Acromegaly, Leukemia.
Deficiency of insulin
Ans : MAIN 2019

Leukemia Others are hormonal disorders 64. Two hormones secreted by neurohypophysis.
Ans : MAIN 2000
54. Insulin, Adrenaline, Pepsin, Thyroxine.
Oxytocin and vasopressin
Ans : SQP 2019

Pepsin Others are hormone 65. The structure which controls the master gland.
Ans : SQP 2007

DIRECTION : Name the following : Hypothalamus

55. The pituitary hormone which stimulates 66. The disease caused by iodine deficiency.
contraction of uterus during child birth. Ans : SQP 2010

Ans : COMP 2017 Goitre

Oxytocin
67. The hormone secreted by thyroid gland.
56. The hormone secreted by beta cells of islets of Ans : MAIN 2012
langerhans.
Thyroxine
Ans : MAIN 2001
68. The hormone secreted by the beta cells of
Insulin
pancreas.
57. An endocrine gland. Ans : COMP 2015
CH 10 : THE ENDOCRINE SYSTEM

194. Complete the following table by filling in the TWO MARKS QUESTIONS
blank spaces 1 to 8

Name of the Substance One important

196. Expand the abbreviation — ADH. Give one
Gland produced function
example of a diuretic substance.
Islets of 1._______ 2._______
Ans : SQP 2025
Langerhans
Antidiuretic Hormone
3._______ Adrenaline 4._______
Alcohol, Coconut water, Caffeine, etc.
5._______ Thyroxine 6._______
197. Why is Adrenaline called 'The Emergency
7._______ LH 8._______
Hormone'?
Ans : COMP 2017 Ans : SQP 2025

1. Insulin It is secreted under conditions of stress like anger,

2. Controls sugar level in the body fear, excitement. It prepares the body to face the
3. Adrenal emergency situation.
4. Increases heart beat
5. Thyroid 198. What are Tropic hormones? Give one example
6. Controls basal metabolism of cells Ans : SQP 2025
7. Pituitary gland
8. Stimulates the production of progesterone/ They stimulate other endocrine glands to secrete
testosterone. their specific hormones. E.g. TSH.

195. Answer the following briefly : 199. Name the mineral elements required for
(i) Clotting of blood
(i) If you stand to make your maiden speech
(ii) Synthesis of thyroxine
before a large audience, your mouth dries up
and heart beat increases. What brings about Ans : MAIN 2024
these changes? (i) Calcium
(ii) What are endocrine glands ? (ii) Iodine
(iii) Explain briefly – ‘Glucose is normally not
found in urine’. 200. Define the term-Diapedesis.
(iv) Why are hormonal reactions generally slower Ans : MAIN 2024
than nervous reactions. Diapedesis is the process by which white blood
(v) A diabetic person has high concentration of cells squeeze out through the walls of capillaries
sugar in urine-what is this condition known to reach at the site of infection.
as ?
201. Define the term hormone.
Ans : SQP 2021
Ans : MAIN 2024
(i) Adrenaline is secreted by Adrenal medulla
which brings about these changes. A hormone is a chemical messenger produced by
glands or specialised cells, circulating in bodily
(ii) The glands which pour their secretion directly
fluids to regulate various physiological processes
into the blood are known as endocrine glands.
in the body.
(iii) Insulin converts excessive glucose in blood to
glycogen which is stored in liver. 202. Give logic for why insulin is injected into the body
(iv) Nervous reactions are co-ordinated by nerve of a highly diabetic patient and not given orally?
impulses which travel very fast, whereas Ans : MAIN 1996
hormonal reactions are co-ordinated by
hormones which travel through blood hence Insulin is a protein, if it is given orally it will
they are slow. be digested in the intestine. Thus, it is injected
directly into the blood.
(v) Glycosuria.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 333

90. The hormone which stimulates the breakdown of Ans : MAIN 2019

glycogen in liver to glucose. False

Ans : COMP 2016
100. Acromegaly is caused due to an increase in the
Glucagon concentration of growth hormone.
Ans : COMP 2021
DIRECTION : State true or false. Write correct True
statement by changing first word only.
101. Myxedema is caused due to malfunctioning of
91. Testosterone is an androgen. thyroid gland.
Ans : MAIN 2006 Ans : SQP 2002

True True

92. The pituitary gland is both exocrine and endocrine 102. Hormones are produced by endocrine gland.
in function.
Ans : MAIN 2009
Ans : COMP 2009
True
False Pancreas is both exocrine and endocrine in
function. 103. Insulin is produced by alpha cells of pancreas.
Ans : COMP 2012
93. Incorporation of iodine into table salt may reduce
the incidence of simple goitre. False
Ans : SQP 2014 104. Thyroid gland secretes adrenaline.
True
Ans : SQP 2021
94. The failure of estrogens result in eunuchoidism. False
Ans : MAIN 2020
105. Adrenal gland is called master gland.
False
Ans : MAIN 2010
95. Vasopressin is related with the concentration of
urine. False

Ans : SQP 2005 106. Deficiency of iodine causes simple goitre.

True Ans : MAIN 2018

96. A hormone responsible for puberty in male is True

testosterone. 107. Oxytocin is water retaining hormone.
Ans : SQP 2001
Ans : SQP 2013
True False
97. Prolactin stimulates milk secretion and growth of
breast. 108. Hormones are chemically protein.

Ans : COMP 2004

Ans : COMP 2004

True True

98. Thyroid gland secretes adrenaline. 109. Glucagon converts glucose into glycogen.
Ans : SQP 2015 Ans : SQP 2000

False False

99. Hormones are chemically proteins.

110. Adrenal medulla produces adrenaline.
CH 10 : THE ENDOCRINE SYSTEM

141. (i) Diabetes mellitus and Diabetes insipidus 145. Why people living in hilly regions usually suffer
(ii) Acromegaly and Myxedema from simple goitre ?
Ans : COMP 2004 Ans : SQP 2011, 2005, 1996

Because the soil and water in hilly region is

(i) Diabetes mellitus Diabetes insipidus deficient in Iodine.
Caused by Caused by
oversecretion of oversecretion of 146. Name the endocrine gland that secretes Thyroxine.
somatotropin from somatotropin after Give any one function of Thyroxine.
childhood. adolescence. Ans : SEM II, 2021

(ii) Acromegaly Myxedema Thyroid gland. It regulates basal metabolism.

Dua to oversecretion Due to low 147. Give the full form of the abbreviation ACTH.
of growth hormone secretion of Which gland secretes this hormone ?
in adults. thyroxine in adults.
Ans : SEM II, 2021

142. Difference between Diabetes mellitus and Diabetes Adreno cortico tropic hormone, Anterior pituitary
insipidus (reason/cause) gland secrete this.
Ans : MAIN 2012
148. Name the form in which glucose is stored in liver.
Diabetes mellitus : Due to hyposecretion of insulin
Ans : COMP 2023
Diabetes insipidus : Due to hyposecretion of ADH
hormone Glycogen

143. Insulin and Glucagon 149. Expand the following biological abbreviations :
TSH
Ans : SQP 2012
Ans : SQP 2019

Insulin Glucagon Thyroid stimulating hormone

(a) It is secreted by It is secreted by
b -cells of Islets a -cells of Islets DIRECTION : Define the following :
of Langerhans of of Langerhans of
pancreas. pancreas. 150. Endocrine glands
(b) It converts the It converts glycogen Ans : MAIN 2002
excess of glucose into glucose.
into glycogen. The glands without ducts are called endocrine
glands. These produce hormones.

151. Hormones
DIRECTION : Choose the correct option :
Ans : COMP 2008

144. (i) Which of the following gland has both The secretions of endocrine glands which are
endocrine and exocrine function (Pituitary, carried by blood to the target organs.
thyroid, pancreas, adrenal)
(ii) (Myxedema, simple goitre, exophthalmic 152. Exophthalmic goitre
goitre) is a disorder caused by excess thyroid Ans : SQP 2004
hormone.
(iii) Insulin is secreted by (delta cells of pancreas, The hypersecretion of thyroxine causes this
alpha cells of pancreas, Beta cells of pancreas, disease. Its symptom is protrusion of eyeball.
none of these).
153. Gigantism
Ans : COMP 2000
Ans : MAIN 2016
(i) Pancreas
A condition caused by the hypersecretion of
(ii) Exophthalmic goitre
growth hormone by pituitary gland.
(iii) Beta cells of pancreas
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 335

131. Maturation of graafian follicle 136. Complete the following table by filling in blank
space 1 to 8.
Ans : SQP 2000

Follicle stimulating hormone Name of Substance One

Gland produced Important
132. Descent of testes into scrotum function
Ans : MAIN 2004 Beta cells 1._______ 2._______
Testosterone Islets of
Langerhans
133. Glucocorticoid secretion 3._______
Ans : COMP 2017
5._______ Adrenaline 4._______
Adrenocorticotropic hormone 7._______ Thyroxine 6._______
134. Sodium and potassium ion metabolism LH 8._______
Ans : SQP 2019 Ans : COMP 2004
Aldosterone. 1. Insulin
2. Regulates blood sugar level
DIRECTION : Complete the following table : 3. Adrenal gland
4. Prepares the body for ‘Flight’ or ‘fight’
135. Complete the following table by filling in the actions.
blanks from 1 to 10 with appropriate terms : 5. Thyroid gland
6. Promotes tissue metabolism, growth and
S. Gland Secretion Function/Effect
differentiation.
No. on body
7. Anterior lobe of pituitary gland.
1. Thyroid 1 2 8. Stimulates ovulation, maintenance of corpus
2. 3 Vasopressin 4 luteum and secretion of progesterone in
females and secretion of testosterone in males.
3. 5 6 Promotes glucose
utilization by the DIRECTION : State the exact location :
body cells.
137. Thyroid gland.
4. Lacrimal 7 8
gland Ans : SQP 2016

5. Adrenal 9 10 Below the larynx or ventro-lateral sides of larynx.

medulla
138. Pituitary gland.
Ans : MAIN 2013
Ans : COMP 2011
1. Thyroxine Base of midbrain close to hypothalamus.
2. Regulates oxidation of food/basal metabolic
rate/promotes tissue metabolism, growth and 139. Islets of Langerhans
differentiation.
Ans : MAIN 2017
3. Posterior pituitary gland
4. Increases re-absorption of water from kidneys In the pancreas.
(reduces loss of water in urine)/contraction of
blood vessels causing rise in blood pressure. DIRECTION : Differentiate between :
5. Adrenal cortex
6. Glucocorticoids 140. Difference between Vasopressin and Insulin
7. Tears (Deficiency disorder)
8. Lubricates eye
9. Adrenaline Ans : MAIN 2015

10. Prepares body from any emergency situation Vasopressin – Diabetes insipidus
Insulin – Diabetes mellitus
CH 10 : THE ENDOCRINE SYSTEM

Insulin 80. The disease caused due to the deficiency of iodine.

69. A mixed gland Ans : COMP 2002

Ans : MAIN 2017

Simple goitre

Pancreas 81. The hormone which controls the water exchange

in the renal tubules.
70. A hormone that controls basal metabolic rate.
Ans : MAIN 2000
Ans : SQP 2020
ADH (Anti-diuretic Hormone)
Thyroxine
82. The hormone that controls the basal metabolic
71. The gland that regulates calcium in blood. rate.
Ans : COMP 2023 Ans : SQP 2004
Parathyroid Thyroxine
72. The chemical messengers. 83. The condition which results in abnormally
Ans : MAIN 2021 long bones, long lower jaw bone due to the
hyposecretion of a pituitary hormone.
Hormones or Adrenalin.
Ans : MAIN 2010
73. The master gland.
Acromegaly
Ans : SQP 2019
84. The hormone associated with the metabolism of
Pituitary gland
carbohydrates, proteins, calcium and phosphorus.
74. A condition caused due to the hyposecretion of Ans : COMP 2007
thyroxine in children.
Thyroxine
Ans : COMP 2018
85. The hormone that controls the calcium content in
Cretinism
blood plasma and its metabolism.
75. The hormone which prepares the body for defense. Ans : SQP 2017

Ans : MAIN 2016 Calcitonin

Emergency hormone/Adrenaline
86. The hormone which regulates carbohydrate
76. The endocrine cells present in pancreas. metabolism.

Ans : COMP 2011 Ans : MAIN 2009

Islets of Langerhans- a -cells, b -cells and d -cells. Insulin

77. A hormone secreted by thyroid gland. 87. The hormone which promotes re-absorption of
water from nephrons.
Ans : SQP 2009
Ans : COMP 2005
Thyroxine
ADH
78. A hormone secreted by adrenal gland.
88. The hormone which increases blood glucose level.
Ans : MAIN 2006
Ans : SQP 2010
Adrenaline
Glucagon
79. A condition caused due to the oversecretion of
thyroxine. 89. The Father of Endocrinology.

Ans : SQP 2004 Ans : MAIN 2013

Exophthalmic goitre Thomas Addison

ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 337

154. Acromegaly produced by the pancreas. Insulin decreases the

blood sugar level while glucagon increases the
Ans : SQP 2020
blood sugar level.
A condition caused by hypersecretion of growth
hormone in adults. Its symptoms are extra growth 162. What is Endocrinology ?
of bones of the face, hands and feet. Ans : SQP 2004

The science which deals with endocrine or ductless

DIRECTION : Answer the following questions: gland and their functions.

155. Define the term exocrine gland with an example. 163. What is Cushings syndrome ?
Ans : COMP 2011 Ans : MAIN 2000

A gland which pours its secretion into a particular It is disorder caused by hypersecretion of adrenal
organ through duct. cortex, resulting in excessive production of
For example, salivary gland, gastric gland, liver, glucocorticoids.
etc.
164. Where are the tropic hormones produced and
156. What are hormones? stored ?
Ans : SQP 2015 Ans : SQP 2011

Hormones are the secretions of endocrine glands In the anterior lobe of pituitary gland.
which are directly poured into the blood stream.
165. Match the items in column I with those in column
157. Name some endocrine glands. II :
Ans : MAIN 2016 Column I Column II
Pituitary, Thyroid, Adrenal, Pancreas, etc. 1. Cretinism a. shortage of glucose in
blood
158. What are endocrine glands?
2. Diabetes b. over secretion of
Ans : COMP 2020
mellitus growth hormone
The glands which do not possess ducts are called 3. Insulin shock c. excess of glucose in
ductless or endocrine glands. These glands seem blood
to secrete hormones.
4. Gigantism d. oversecretion of
159. Briefly write about thyroid gland. thyroxine
Ans : MAIN 2018 5. Exophthalmic e. dwarfism and mental
goitre retardation
Thyroid gland is a bilobed structure located
in front of the neck just below the larynx. It 6. Acromegaly f. oversecretion of GH
produces two hormones, thyroxine and calcitonin. in adults
Thyroxine regulates the basal metabolism. 7. Addison’s g. oversecretion of
Calcitonin controls the calcium level of blood. disease insulin
160. Why are hormones called as ‘chemical messengers’ ? 8. Tetany h. undersecretion of GH
Ans : SQP 2020 9. Dwarfism i. Decreased calcium in
blood
Hormones are chemicals which are directly poured
into the blood stream and carried to all the parts Ans : MAIN 2009
of the body for the proper working of the body.
l. " e; 2. " c;
161. What are antagonistic hormones? 3. " g; 4. " b;
5. " d; 6. " f;
Ans : COMP 2013
7. " a; 8. " i;
Antagonistic hormones are those that work 9. " h.
against each other, e.g. insulin and glucagon
CH 10 : THE ENDOCRINE SYSTEM
Ans : MAIN 2022
Glucagon
True
120. Regulates basal metabolism
111. Myxoedema is caused due to the malfunctioning Ans : SQP 2013
of thyroid gland. Thyroxine
Ans : SQP 2020
121. Ossification of bones
True
Ans : MAIN 2011
112. The pituitary gland is both exocrine and endocrine Thyroxine
in function.
Ans : COMP 2018
122. Prepares the body during emergency

False Ans : COMP 2010

Adrenaline
113. Enzymes are secreted directly into the organs.
Ans : MAIN 2017 123. Responsible for normal growth of the whole body.
True Ans : SQP 2008

114. Hormones are secreted directly into the blood. Growth hormone

Ans : SQP 2012 124. Regulates the functioning of the male and female
True reproductive organs.
Ans : MAIN 2000

DIRECTION : The statements given below are Gonadotropic (Somatotropin)

false. Rewrite the correct form of the statement by
changing the word which is underlined : 125. Increased absorption of water in the kidneys.
Ans : SQP 2003
115. Alpha cells of pancreas secrete Insulin.
Vasopressin
Ans : COMP 2011
126. Increased blood supply to muscles.
Alpha cells of pancreas secrete Glucogen.
Ans : COMP 2009
116. Cretinism is caused due to deficiency of
Adrenaline.
Adrenaline.
Ans : MAIN 2008 127. Urinary elimination of water
Cretinism is caused due to deficiency of Thyroxine. Ans : MAIN 2010

Vasopressin
DIRECTION : Name the hormone responsible for
128. Storage of glucose as glycogen
the following functions :
Ans : COMP 2014
117. Increase in heart beat Insulin
Ans : SQP 2009
129. Milk secretion
Adrenaline
Ans : SQP 2008
118. Maintains glucose level in the blood Oxytocin
Ans : MAIN 2022
130. Heart beat and blood pressure
Insulin
Ans : COMP 2006
119. Converting glycogen to glucose Thyroxine
Ans : COMP 2017
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 339

Because insulin is a protein and if given orally will 183. Adrenal medulla produces ______.
be digested by the digestive system and its effect
Ans : MAIN 2023
will be reduced.
Adrenaline and noradrenaline

DIRECTION : Fill in the blanks : 184. ______ Secretes both hormones as well as
enzymes.
174. ______ Gland stimulates growth and Ans : SQP 2001
stimulates secretion of hormones from other
glands. Pancreas

Ans : MAIN 2010 185. Diabetes mellitus is caused due to the deficiency
of ______.
Pituitary
Ans : COMP 2004
175. ______ Hormone from thyroid regulates
Insulin
calcium and phosphate levels in the blood.
Ans : COMP 2015 186. Diabetes insipidus is caused due to the deficiency
of ______.
Calcitonin
Ans : SQP 2009
176. ______ Stimulates contraction of uterus
ADH
during labour.
Ans : SQP 2018 187. The alpha cells of pancreas produce ______.
Oxytocin Ans : MAIN 2022

Glucagon
177. The two lobes of thyroid gland are joined by
______. 188. Adrenal gland : Kidney : : Pituitary gland :
Ans : MAIN 2020 ______
Gigantism Ans : COMP 2023

Brain
178. The ______ glands produce hormones.
Ans : COMP 2023 189. ______ is the master gland.
Endocrine (ductless) Ans : MAIN 2006

Pituitary gland
179. The ______ is called as emergency hormone.
Ans : SQP 2016 190. Insulin is produced by the ______ of Islets of
Langerhans.
Adrenaline
Ans : SQP 2007
180. Corpus luteum secretes ______ hormone. b -cells
Ans : COMP 2011
191. Emergency hormone is ______.
Progesterone
Ans : COMP 2016
181. Exophthalmic goitre is caused due to the Adrenaline
hypersecretion of ______ .
Ans : SQP 2020
192. Hypothyroidism causes ______.

Thyroxine Ans : SQP 2004

Simple goitre
182. The glands with ducts are called ______.
Ans : COMP 2014
193. a -cells produce ______ hormone.

Exocrine/ducted glands Ans : MAIN 2013

Glucagon
CH 10 : THE ENDOCRINE SYSTEM

organism and transported in tissue fluids such as THREE MARKS QUESTIONS

blood or sap to stimulate specific cells or tissues
into action.
216. Given figure is the outline of the human body.
214. Match the items given in Column A with the Reudraw the same and then place the following
most appropriate ones in Column B and rewrite organs in the correct position and label them :
the correct matching pairs. 1-Thyroid gland; 2-Windpipe; 3-Diaphragm;
Column A Column B 4-Right and left lungs; 5-Right and left kidneys;
6-Adrenal glands.
(i) Cretinism (a) Hypersecretion of
adrenal cortex
(ii) Diabetes (b) Hyposecretion of
insipidus thyroxine
(iii) Exophthalmic (c) Hyposecretion of
goitre growth hormone
(iv) Adrenal virilism (d) Hyposecretion of
vasopressin
(v) Dwarfism (e) Hyposecretion of
adrenal cortex
(f) Hypersecretion of
growth hormone
(g) Hypersecretion of
thyroxine
(i) Name the hormone produced by the thyroid
Ans : SQP 2018
gland and state its function in the body.
(ii) What would a child suffer from if there was
Column A Column B hyposecretion of this gland ?
(i) Cretinism Hyposecretion of (iii) What role does the diaphragm play in the
thyroxine inspiration of air. Explain briefly.

(ii) Diabetes insipidus Hyposecretion of Ans : MAIN 1999

vasopressin (i) Thyroxine - It controls cellular respiration/

controls carbohydrate metabolism.
(iii) Exophthalmic Hypersecretion of
goitre thyroxine
(iv) Adrenal virilism Hypersecretion of
adrenal cortex

(v) Dwarfism Hyposecretion of

growth hormone

215. Give biological reasons : People living in hilly

regions usually suffer from simple goitre.
Ans : COMP 2011

Iodine is deficient in the soil of hilly regions, hence

(ii) Cretinism.
iodine is also deficient in the crops grown. So,
(iii) During inhalation, the diaphragm flattens
people consume less iodine in their food. Iodine
and the volume of thoracic cavity increases
is needed for the production of thyroxine. Due to
and during exhalation diaphragm become
the deficiency of iodine, people suffer from simple
dome-shaped thus decreasing the volume of
goitre, i.e. swelling in the neck.
thoracic cavity.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 341

203. Give appropriate biological or technical term for 208. Write briefly about :
the following : (i) Exophthalmic goitre (Symptoms and cause).
Hormones which regulate the secretion of other (ii) Diabetes mellitus (symptoms and cause).
endocrine glands.
Ans : COMP 1995
Ans : SQP 2018
(i) Symptoms : Thyroid enlarged, eyes protrude
Tropic hormone out, high blood pressure and increase in body
temperature, patient loses weight.
204. Simple goitre is usually seen in people living in the Cause : Excess of thyroxine secreted by
hilly regions. Give two reasons for the statement. thyroid gland.
Ans : COMP 2021 (ii) Symptoms : Increased thirst and urination,
increased appetite, presence of glucose in
Two reasons are :
urine.
(i) Deficiency of Iodine in the soil.
Cause : Under secretion of insulin.
(ii) Iodine is an active ingredient in the production
of thyroxine. 209. Define :
(i) Endocrine gland.
205. What is Adrenal Virilism ? What causes this
(ii) Hormone
condition ?
Ans : MAIN 2010, 1994
Ans : SEM II, 2021
(i) Endocrine glands are ductless glands which
Development of male characters like beard,
secretes hormones.
moustaches and deep male voice in female.
(ii) Hormones are the secretions from specific
Cause : Over growth of adrenal cortex due to which
cells or glands in the body and are carried to
excess secretion of male hormone androsterone
all parts of the body by the blood but their
takes place.
effect is produced in one or more specific
206. Name the hormones whose deficiency causes : parts only.
(i) Diabetes mellitus
210. What is the cause of developing facial hair in
(ii) Diabetes insipidus
some women?
Ans : SEM II, 2021
Ans : COMP 2023
(i) Insulin
The development of facial hair in some women
(ii) Antidiuretic hormone or Vasopression.
is due to the overgrowth of adrenal cortex which
207. Make a very simple outline sketch of the human produces cortisol.
body and locate different endocrine glands and
211. How is iodine important to our body?
their position in it.
Ans : SQP 2020
Ans : MAIN 1985
Iodine is needed for the synthesis of thyroxine. Its
deficiency causes goitre.

212. Give biological reasons for the following

statements: Some women have facial hair like
beard and moustache.
Ans : COMP 2017

Some women have facial hair like beard and

moustache because of adrenal virilism, in which
excess secretion of adrenal androgen takes place
and causes this male effect in females.

213. Briefly explain the term hormone.

Ans : SQP 2016

Hormone is a regulatory substance produced in an

CH 10 : THE ENDOCRINE SYSTEM

166. Make a table indicating the following glands (iii) Diabetes insipidus Diabetes mellitus
(Pituitary, Thyroid, Pancreas and Adrenal),
hormones produced by them, their main functions 1. Caused due to 1. Caused due to
and diseases caused due to their hyposecretion under secretion under secretion of
and hypersecretion. of antidiuretic insulin hormone.
hormone. 2. Glucose is
Ans : MAIN 2003
2. Large quantity excreted along with
Glands Hormones Functions Diseases of water is lost urine.
along with urine
1. Growth Growth of Gigantism
Pituitary hormone the body (hyper-
but glucose is not
Antidiuretic Re-absorption secretion) excreted.
hormone of water Dwarfism
by kidney (hypo-
(iv) Insulin Glucagon
tubules secretion) 1. Secreted by beta 1. Secreted by the
2. Thyroxine Basal Diabetes cells of islets of alpha cells of islets
Thyroid metabolic insipidus langerhans. of Langerhans.
rate (BMR) Cretinism,
2. Converts glucose 2. Converts
exophthalmic
goitre into glycogen and glycogen into
lowers the blood glucose and
3. Insulin Glucose to Diabetes
Pancreas glycogen mellitus glucose level. increases blood
glucose level.
4. Gluco- Control of Addison’s
Adrenal corticoides carbohydrate disease (hypo-
Mineral- and protein secretion) 168. Why do people living in hilly region usually suffer
ocorticoides metabolism Cushing from simple goitre ?
Control syndrome
of mineral (hyper- Ans : COMP 2002
metabolism secretion)
Due to deficiency of iodine in their vegetation and
167. Mention two differences in each case : water.
(i) Dwarfism and gigantism
(ii) Cretinism and myxedema 169. What is virilism ?
(iii) Diabetes insipidus and diabetes mellitus Ans : SQP 2017
(iv) Insulin and glucagon The presence or development of secondary male
Ans : COMP 2018 characters in a woman.

(i) Dwarfism Gigantism 170. What are the symptoms of virilism ?

1. Caused due to 1. Caused due to Ans : MAIN 2015
deficiency of growth oversecretion of Growth of beard, decrease in size of breast, low
hormone. growth hormone. pitch voice, and lack of menstruction in females.
2. Characterised 2. Characterised
by stunted growth by growth of long 171. What are tropic hormones ?
and poor sexual bones resulting in
Ans : COMP 2020
development. abnormal height.
The hormones which stimulate other endocrine
(ii) Cretinism Myxedema glands to release their hormones.
1. Caused due to 1. Caused due to
172. In which sex is exopthalmic goitre more common?
malfunctioning of malfunctioning of
thyroid in children. thyroid in adults. Ans : MAIN 2017
2. Results in 2. Results in lower In females.
retarded physical basal metabolism,
and mental swollen face, 173. Why is insulin injected into the body of a diabetic
development, short physical and patient and not given orally ?
hand, feet and mental dullness
Ans : COMP 2000
pigeon chest. and impotency.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 343

217. Write three differences between hormones and (iii) Adrenal medulla : Adrenaline - Increases
enzymes. heart beat and blood pressure
Ans : MAIN 2010
221. How do hormonal control differ from nervous
The differences between hormones and enzymes control?
are as follows : Ans : SQP 2019

Hormones Enzymes The differences between hormonal control and

1. Hormones are Enzymes are nervous control are as follows:
secreted by secreted by exocrine Hormonal Control Nervous Control
endocrine glands. glands.
(a) Slow. (a) Spontaneous.
2. Hormones generally Enzymes act where
act away from the these are secreted. (b) Chemical signals (b) Signals
site of secretion. are transmitted transmitted
through blood. electrochemically
3. Hormones may Enzymes are always through nerve
or may not be proteins. fibres.
proteins.
(c) Its effects are (c) Effects are short-
long lasting. lived.
218. If one adrenal gland is removed the other one gets
enlarged to some extent. Explain.
222. Insulin is injected into the body of a highly
Ans : MAIN 2016 diabetic patient and is not given orally. Explain.
The remaining adrenal gland has to double its Ans : MAIN 2012
works like-send more glucose and oxygen to the
muscle to secrete the emergency hormone, etc. Insulin is a protein hormone and if it is given
Therefore it gets enlarged. orally it would be digested upon by the protein
digesting enzymes in the alimentary tract.
219. What is feedback mechanism ? Explain one
example. 223. Name the part of human body in which the
following glands are located:
Ans : SQP 2017 (i) Thyroid
Feedback mechanism is one in which a tropic (ii) Adrenal
hormone stimulates a gland to secrete its (iii) Pituitary
hormone, which in turn inhibits the secretion of Ans : COMP 2009
the hormone of anterior pituitary. For example
TSH – RH stimulates thyroid gland to secrete (i) Thyroid – Neck;
thyroxine. But oversecretion of thyroxine inhibits (ii) Adrenal – Above Kidney;
the anterior pituitary to slow down the secretion (iii) Pituitary – Brain
of TSH – RH, so that a normal level of thyroxine
224. Explain tropic hormone.
is maintained in blood.
Ans : SQP 2017
220. Name the hormones produced by the following
Tropic hormone is a hormone which targets other
glands. In each case state one function of the
endocrine glands. It is secreted from the anterior
hormone.
lobe of pituitary gland. For example, TSH, which
(i) Thyroid
stimulates thyroid gland to secrete thyroxine.
(ii) Pancreas
(iii) Adrenal medulla 225. Complete the following table :
Ans : MAIN 2000
Gland Secretions Effect on Body
(i) Thyroid : Thyroxine and calcitonin -
1 Oestrogen 2
Thyroxine controls metabolic rates of
carbohydrate, protein and fat. Alpha cells of 3 4
(ii) Pancreas : Insulin and glucagon - insulin pancreas
decreases blood glucose level.
CH 10 : THE ENDOCRINE SYSTEM

5 6 Protruding eyes (iii) ADH – It controls the reabsorption of water

in the kidney tubules.
Lacrymal 7 8
9 10 Gigantism

Ans : COMP 2004

FIVE MARKS QUESTIONS
1. Ovary
2. Responsible for developing characters of
230. Given below is the outline of the human body
females.
showing the important glands :
3. Secrete glucagon
(i) Name the glands marked 1 to 4.
4. Glucagon helps to convert glycogen stored in (ii) Name the hormone secreted by part 2. Give
liver to glucose one important function of this hormone.
5. Thyroid
6. Thyroxine
7. Tears
8. Tears lubricate the eyes and prevent dust
from entering in the eye.
9. Pituitary gland.
10. Growth hormone (somatotropin).

226. Explain briefly Glucose is normally not found in

urine.
Ans : COMP 2002

Excess glucose in the blood is converted into

glycogen by insulin. Also it is reabsorbed in the
proximal convoluted part of nephron.

227. Name antagonistic hormones. Write their actions.

Ans : MAIN 2018
(iii) Name the endocrine part of the part numbered
Insulin and glucagon are the antagonistic 3.
hormones. Insulin reduces the blood sugar (iv) Why is the part labelled 1 called the master
level while glucagon increases the glucose level. gland? Which part of the fore-brain controls
Antagonistic means that both hormones showing the gland labelled 1 ?
opposite action against each other. (v) Name the gland that secretes the ‘emergency
hormone’.
228. What is Virilism? What are the symptoms?
Ans : SQP 2016
Ans : SQP 2013
(i) 1-Pituitary gland, 2-Thyroid gland,
The presence or the development of male 3-Pancreas, 4-Adrenal gland
secondary characters in a women. (ii) Thyroxine hormone, it controls basal
The symptoms are: metabolic rate.
Growth of beard, lack of menstruation, decreased (iii) Islet of Langerhans.
breast size. (iv) Pituitary gland is known as the master gland
of the body because it controls other endocrine
229. Give the function of the following hormones:
glands by the secretion of trophic hormones.
(i) Thyroxine
Floor of diencephalon called hypothalamus
(ii) Insulin
controls the pituitary gland by the secretion
(iii) ADH
of releasing and inhibiting factors/hormones.
Ans : SQP 2009 (v) Emergency hormone is secreted by the adrenal
(i) Thyroxine – It controls the basal metabolism. medulla.
(ii) Insulin – It decreases the blood sugar level.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 345

231. Study the diagram given below and then answer (iii) Name the mineral element required for the
the questions that follow : synthesis of the above mentioned hormone.
(iv) Name the disease caused due to undersecretion
of the above mentioned hormone in children.
(v) Name the disease caused due to hypersecretion
of the above mentioned hormone.
Ans : COMP 2017

(i) Thyroid gland

(i) Name the cells of the pancreas that produce (ii) Thyroxine
(1) glucagon (2) insulin. (iii) Iodine
(ii) State the main function of (1) glucagon (2) (iv) Cretinism
insulin. (v) Exophthalmic goitre/Grave’s disease.
(iii) Why is the pancreas referred to as an exo- 233. The diagram shows some structures in ventral
endocrine gland ? and dorsal view :
(iv) Why is insulin not given orally but is injected (i) Label the parts 1 to 5.
into the body ? (ii) What is common to all these parts in regard
(v) What is the technical term for the cells of the to the nature of their function ?
pancreas that produce endocrine hormones ? (iii) In what way is part 3 different from other
(vi) Where in the body is the pancreas located ? parts shown in the diagram ?
Ans : MAIN 2011 (iv) Name the hormone secreted by testis.
(i) 1. a - cell in islet of Langerhans.
2. b - cell in islet of Langerhans.
(ii) 1. Converts glycogen to glucose.
2. Converts glucose to glycogen.
(iii) Because it contains secretory structures
i.e., acini (exocrine parts) which help in the
digestion.
(iv) Because it will be digested by the proteases
enzymes in the stomach.
(v) Islet of Langerhans.
(vi) Just below the stomach in the loop of
duodenum of small intestine.

232. The diagram given below represents the location

and structure of an endocrine gland. Study the
same and answer the questions that follow : Ans : MAIN 2008

(i) 1. Pituitary gland

2. Thyroid gland
3. Pancreas
4. Adrenal glands
5. Ovary
(ii) All are ductless glands which secrete hormones
to act away from the site of their production.
(iii) Part 3 pancreas is both endocrine and
exocrine in function.
(iv) Testosterone

(i) Name the endocrine gland shown in the 234. The diagram given below represents an endocrine
diagram. gland in the human body. Study the diagram and
(ii) Name the secretion of the gland which answer the following questions :
regulates basal metabolism.
CH 10 : THE ENDOCRINE SYSTEM

(i) Identify the endocrine gland. Where is it

located?
(ii) Why is the above gland referred to as the
‘Master gland’ ? (i) Name the condition.
(iii) Name the hormone which in deficiency causes (ii) What is the underlying cause of this condition?
Diabetes Insipidus. How does this disorder (iii) Name two other conditions that could have
differ from Diabetes Mellitus ? resulted due to a similar cause.
(iv) Explain the term ‘Hormone’. (iv) Which hormone is required for iodine
What is the role of Tropic hormones in the synthesis ?
human body ? (v) Where is thyroid gland located ?
(v) Which lobe of the above gland secretes :
1. Oxytocin Ans : COMP 2017

2. ACTH (i) Goitre

3. Growth hormone (ii) Thyroid gland enlarges due to deficiency of
Ans : MAIN 2019
iodine in the diet.
(iii) 1. Cretinism
(i) Pituitary gland. 2. Myxedema
Location - Hangs from the base of midbrain (iv) Thyroxine
below hypothalamus of brain. (v) Thyroid gland occupies a mid ventral position
(ii) Because it controls practically all other in the posterior part of larynx in neck region.
endocrine gland.
(iii) Antidiuretic hormone Its deficiency causes
diabetes insipidus (hypoglycemia). Insufficient
secretion of insulin causes diabetes mellitus
(hyperglycemia). It passes sugar in urine.
CASE BASED QUESTION
(iv) Hormone is the secretion from some glandular
part of the body which is poured directly 236. Nisha, a 30-year-old woman, has been feeling
into blood and which acts on target organs unusually fatigued, gaining weight, and
or cells of same individual, bringing about experiencing hair loss. Her doctor diagnosed
coordination between distant parts of the her with hypothyroidism, a condition where the
body. thyroid gland does not produce enough thyroxine.
Tropic hormones stimulate other endocrine This hormone is crucial for regulating metabolism,
gland to produce their specific hormone. and its deficiency has slowed down her body’s
(v) 1. Posterior lobe metabolic rate.
2. Anterior lobe 1. What is the function of thyroxine in the
3. Anterior lobe body?
2. How does hypothyroidism affect metabolism?
3. What are common symptoms of
hypothyroidism?
235. The sketch shows a certain condition in an 4. How can hypothyroidism be treated?
individual.
Ans :
1 Thyroxine regulates the body’s metabolic
rate and controls energy production.
2. Hypothyroidism slows down metabolism,
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 347

leading to weight gain and fatigue. 239. Rekha, a 28-year-old woman, recently gave
3. Common symptoms include fatigue, weight birth to her first child. During labor, her body
gain, and hair loss. released oxytocin, a hormone that regulates
4. Hypothyroidism can be treated with hormone uterine contractions and facilitates childbirth.
replacement therapy. Her doctor explained that oxytocin also plays a
role in breastfeeding by helping release milk from
237. Amit, a 45-year-old man, was diagnosed with the mammary glands.
diabetes mellitus after experiencing excessive 1. What is the role of oxytocin during childbirth?
thirst, frequent urination, and fatigue. His doctor 2. How does oxytocin help with breastfeeding?
explained that his pancreas was not producing 3. Which gland secretes oxytocin?
enough insulin, a hormone responsible for 4. What are other functions of oxytocin in the
regulating blood sugar levels. body?
1. What is the role of insulin in the body?
2. How does a lack of insulin cause diabetes Ans :
mellitus? 1. Oxytocin stimulates uterine contractions,
3. What are the symptoms of diabetes mellitus? helping in the childbirth process.
4. How is diabetes mellitus managed? 2. It aids in the release of milk from the
Ans : mammary glands during breastfeeding.
3. The posterior pituitary gland secretes
1. Insulin helps regulate blood sugar by oxytocin.
facilitating the uptake of glucose into cells. 4. Oxytocin also helps in bonding and emotional
2. A lack of insulin leads to high blood sugar regulation.
levels, causing diabetes mellitus.
3. Symptoms include excessive thirst, frequent 240. Sanjay, a 40-year-old man, has been experiencing
urination, and fatigue. weight gain, high blood pressure, and muscle
4. Diabetes is managed through insulin therapy, weakness. His doctor diagnosed him with
diet, and exercise. Cushing’s syndrome, a condition caused by the
overproduction of cortisol by the adrenal glands.
238. Raj, a 25-year-old man, was involved in a minor This hormone, while important for managing
car accident. During the incident, his heart raced, stress, can cause significant health issues when
and he felt a surge of energy. His doctor explained produced in excess.
that the adrenal glands had released adrenaline, a 1. What is cortisol, and what is its primary
hormone that prepares the body for the ‘fight or function?
flight’ response during stressful situations. 2. How does overproduction of cortisol lead to
1. What is the function of adrenaline in the Cushing’s syndrome?
body? 3. What are common symptoms of Cushing’s
2. How does adrenaline help the body respond syndrome?
to stress? 4. How is Cushing’s syndrome treated?
3. What are the physical effects of adrenaline
release? Ans :
4. Which gland produces adrenaline, and where 1. Cortisol helps regulate metabolism and
is it located? manage stress responses.
Ans : 2. Excess cortisol disrupts metabolism, leading
to Cushing’s syndrome.
1. Adrenaline prepares the body for immediate 3. Symptoms include weight gain, high blood
physical action during stress. pressure, and muscle weakness.
2 It increases heart rate, blood pressure, and 4. Treatment involves reducing cortisol levels,
energy levels to help the body respond often through medication or surgery.
quickly.
3. Physical effects include increased heart rate,
faster breathing, and heightened alertness. www.nodia.in
4. Adrenaline is produced by the adrenal glands
located above the kidneys.
CH 11 : THE REPRODUCTIVE SYSTEM

CHAPTER 11
THE REPRODUCTIVE SYSTEM

male gonad, called testis, produce sperms (male

SUMMARY gamete) and the female gonad, known as ovary,
produces ova (female gamete).
1. REPRODUCTION 3. Sexual Dimorphism :
No organism survives forever and, therefore, if a The phenomenon in which the male and
species is to continue to exist, its members must female individuals of unisexual animals can
reproduce their own kind. Hence, all the living be distinguished externally is called sexual
organisms reproduce their own kind to maintain the dimorphism. Such externally visible characteristics
continuity of their race. Reproduction, therefore, which are restricted in a particular sex are called
helps in the increase of population of the species. secondary sexual characters such as beard,
It transfers the characteristics of parents into the moustaches, deep voice, narrow hips and chest
offspring. A new individual has to go through in man, and bulky hips and developed breasts in
a period of growth and development before it woman.
reaches the stage at which it can reproduce itself. 2. REPRODUCTION IN HUMANS
1.1 Types of Reproduction Reproduction in humans are classifier in the
There are two types of reproduction which are as following parts:
follows : 1. Primary reproductive parts - It includes
gonads (testes in males and ovaries in females)
1. Asexual Reproduction : which produce sex cells (gametes) - sperms
In this type of reproduction a single organism and eggs or ova.
is capable of producing its own kind. The 2. Accessory reproductive parts - Includes
participation of two organisms is not required and all those structures which help in transfer
the individuals produced are genetically identical. and meeting of the two kinds of sex cells
It ensures rapid multiplication and it is mostly a leading fertilization and in the growth and
characteristic feature of lower organisms. development of the egg upto the birth of the
2. Sexual Reproduction : baby.
In this type of reproduction development of new
individual takes place by fusion of two sex cells, 3. THE MALE REPRODUCTIVE SYSTEM
the male and female gametes. Zygote formed by It includes all body organs of man which helps in
the fusion of male (sperm) and female (ovum) the production of male gametes and transference
gametes gives rise to a multicellular embryo by of semen or spermatic fluid in vagina of woman
repeated mitotic division. The embryo gradually collectively constitutes the male reproductive
develops into a full grown animal. system. It includes :
Sexual reproduction is energetically very 1. A pair of testes : They produce sperms.
expensive because large number of gametes must Each testis is enclosed in a capsule internally
be generated of which only a few are used to form partitioned into many lobules and each lobule
zygotes which grow to reproductive maturity. The contains - Seminiferous tubule (where sperms
advantage of sexual reproduction is the generation are produced by spermatogenesis) and
of variation upon which natural selection can act. Interstitial or Leydig cells (which are packing
In higher animals sperms and ova are produced tissues between the coils of seminiferous
in specialized sex organs said to be gonads. The tubules. It produces the male hormone
testosterone. Attached to the basement
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 349

membrane of seminiferous tubule are present 3.1 Parts of Sperm

sertoli cells which are nutritive and provide A sperm consists of :
nutrition to the developing sperms. (i) Head - Consisting of acrosome and nucleus.
2. The Epididymis : Fitting like a cap on the (ii) Neck - Consists of funnel shaped basal body
upper pole of the testis. It stores sperms for and a pair of centrioles, one proximal and one
some days during which they mature and distal, lying at right angles to each other.
become motile. (iii) Middle piece - Composed exclusively of
3. Sperm duct (vas deferens) : The epididymis mitochondria.
is continued by the sides of the testis upto its (iv) Tail - Helps in locomotion of sperms.
back from where a distinct tube sperm duct
arises. It helps to carry sperms. 4. THE FEMALE REPRODUCTIVE SYSTEM
4. Accessory glands : [Seminal vesicles, prostate It includes all body organs of female which help in
and cowper’s (bulbourethral) gland] helps to the process of reproduction. It includes :
contribute to the seminal fluid. The secretion 1. A pair of Ovaries : It is the primary female
of the glands with sperm or spermatozoa is a sex organ. Located near the kidneys they
whitish viscous fluid known as seminal fluid remain attached to the lower abdominal
or semen. The process of expulsion of semen cavity through mesovarium by ovarian
from the urethra is called ejaculation. ligaments. Their peripheral part produces
5. A Penis : Helps in to transfer sperms into the ova. Normally only one egg matures in each
females. ovary every alternate month. A maturing egg
6. Urethra : It is contained inside the penis, in a cellular sac is called follicle. As the egg
conveys sperms received from sperm ducts. grows larger follicles also enlarges and gets
7. Scrotum : It is a thin pouch of skin that filled with a fluid and now called as graafian
houses the testis. It supports the testes and follicle (a matured follicle) which bulges over
maintains temperature 2-3° centigrade lower the surface of ovary for ovulation (rupturing
than the body temperature, necessary for the of the follicle and releasing the ovum outside
maturation of sperms. the ovary). The remnant of the follicle
persists for sometime to convert into a yellow
mass called corpus luteum which continues to
secrete oestrogen and progesterone (female
sex hormones).
2. A pair of Oviduct : Oviduct is also called as
fallopian tube or uterine tube. Each oviduct
has a funnel shaped opening called oviducal
funnel which helps to pick up and push the
released ovum into the oviduct. Oviduct
receives the ovum and provides appropriate
environment for its fertilization and transports
it to the uterus.
3. Uterus : A hollow pear shaped muscular organ
situated in the pelvic cavity between urinary
bladder and the rectum. It is commonly called
as womb. Its lumen is lined by endometrium
which is highly vascular and very rich in
glands. The endometrium undergoes marked
cyclical changes that constitute the menstrual
cycle. The uterus acts as a life support
system, the place where fertilized ovum
(zygote) becomes implanted (fixed) receives
nourishment and develops into an infant.
4. Cervix : The lower part of uterus is very
narrow and is called cervix or neck. The
sperms enter into the uterus through this
CH 11 : THE REPRODUCTIVE SYSTEM

neck. 1. In males puberty starts at the age of 11 years.

5. Vagina : It is a muscular passage that Following changes take place during puberty
connects the uterus with the external world. in males-
Amazingly expandable it serves as receptacle (a) Physical change - Testes enlarges,
for the male penis and sperms for copulation appearance of beard and moustaches,
and a corridor for the emergence of the growth of auxiliary, pubic and chest
baby into the outside world. A thin mucous hairs, pectoral girdle grows more than
membrane called hymen covers the vaginal pelvic girdle.
opening either partly or entirely. The hymen, (b) Sexual change - Spermatogenesis occurs
however, eventually breaks, sometimes during and formation of semen takes place.
sports or other physical activity or during the (c) Mental change - Attraction for girls.
initial act of sexual intercourse. 2. In females, puberty starts at the age of 10 -14
6. Vulva : The external genital organs of years. Following changes take place during
females are collectively called as vulva. It has puberty in females-
independent opening of vagina and urethra. (a) Physical change - Breasts develop and
The sides of vulva has labia minora (lesser enlarge, auxiliary and pubic hair grows,
lips) and labia majora (greater lips), which broadening of hips take place, growth of
are equivalent to the male scrotum. In the long bones stop.
uppermost angle of vulva in front of the (b) Sexual change - Oogenesis takes place
urethral opening is located a small erectile and ovums are formed, menstrual cycle
clitoris which is highly sensitive and is and ovulation begins.
equivalent of male penis. Accessory glands : (c) Mental change - Sexual desire appears.
The vagina remains moistened by Bartholins
glands, which is located one on each side 5.1 Fertilization
of the vaginal opening. They secrete mucus In human female fertilization takes place inside
which helps in lubrication during copulation the fallopian tube i.e. it is internal. During
and parturition. A pair of well developed sexual intercourse or coitus or copulation semen
mammary glands are also present in females or spermatic fluid is released into the vagina of
on the anterior lateral sides of the chest. females by the penis of males. The sperms from
Before puberty these are very small, rounded vagina starts moving towards uterus and then to
structures, but during the attainment of fallopian tube. If there happened to be an egg or
puberty they grow in size. These mammary ovum in the oviduct a large number of sperms
glands secrete milk known as colostrums for surround the egg from all sides. But out of all
the first time after the delivery of the first these sperms only one will be able to enter into
child. the egg and all others die. After entry of sperm
into the ovum the sperm moves towards the
haploid nucleus of egg and fertilizes the egg. As
a result zygote is formed. Fertilization occurs
usually within 24 hours of ovulation.
1. Implantation and Pregnancy
Attaching of developing embryo to the uterine
wall of mother is called implantation. It produces
the state of pregnancy. At the end of fourth day
of fertilization the developing embryo reaches
uterus and is a solid ball of cells called morula
which later converts into a fluid filled embryo
called blastocyst. The outer layer of blastocyst
is nutritive in function and is called trophoblast.
The trophoblast of blastocyst digests and
5. PUBERTY
reabsorbs the uterine endometrium producing
The onset of reproductive life is called puberty. It a pit. In this pit the developing embryo settles
is the time when gonads develop both endocrine and the endometrium grows over it. This is called
and gametogenic functions. implantation which is a must to get nourishment
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 351

and oxygen from the mother for rapid development. (duration of embryonic development, in the
uterus starting from implantation to the birth of
the child). The length of time from conception to
birth (gestation period) is about 280 days.
4. Amniocentesis
A technique to diagnose foetal abnormalities by
drawing a sample of amniotic fluid by a needle
inserted through mother’s abdomen into the
uterus. This fluid contains cells which can be
studied for several defects and also to know the
sex of a child.

2. Placenta
An intimate connection is established between
the foetal membrane and the uterine wall by a
structure known as placenta. The main task of
placenta is to permit the diffusion of nourishment
from mother’s blood to the baby’s and the
disposal of waste products from the baby’s blood
to the mother’s. Stages in the development of human embryo :
3. Parturition Egg (ovum) " zygote " morula " trophoblast
It is the act of expelling the full term foetus " blastocyst " embryo (3 weeks) " advanced
from the mother’s uterus at the end of gestation embryo (5 weeks) " foetus (8 weeks) " infant.

Ans : SQP 2025

MULTIPLE CHOICE QUESTION Thus (b) is correct option.

2. Assertion (A) : The foetus respires but does not

1. The onset of menstruation in a human female is breathe.
called: Reason (R) : The maternal blood supplies oxygen
(a) Menopause (b) Menarche to the foetus through placenta.
(c) Ovulation (d) Oogenesis
CH 11 : THE REPRODUCTIVE SYSTEM

vas deferens, seminal vesicles, and prostate, play Ans : MAIN 2017

supporting roles in the reproductive system but The Cowper’s glands (also known as bulbourethral
do not produce reproductive cells. glands) secrete a clear fluid that helps neutralize
Thus (d) is correct option. the acidity of the urethra and vagina, making
the environment more suitable for sperm during
34. The site of maturation of human sperms is the ejaculation. This fluid acts as a lubricant and
(a) seminiferous tubule protective mechanism for sperm, ensuring its
(b) interstitial cells viability as it travels through the reproductive
(c) prostate gland tract.
(d) epididymis Thus (d) is correct option.
Ans : MAIN 2023
38. When pregnancy does not occur, the life of corpus
Sperms mature in the epididymis, where they gain luteum is about-
motility and the ability to fertilize an egg. While (a) 4 days (b) 10 days
sperm are produced in the seminiferous tubules, (c) 28 days (d) 14 days
they must mature in the epididymis before being
ready for fertilization. Ans : SQP 2008

Thus (d) is correct option. After ovulation, the corpus luteum forms from
the ruptured follicle and secretes progesterone
35. The middle piece of sperm provides to maintain the uterine lining. If fertilization
(a) food (b) energy and pregnancy do not occur, the corpus luteum
(c) gene (d) chromosomes degenerates after about 14 days, leading to a drop
Ans : COMP 2016 in progesterone levels, which triggers the start of
menstruation
The middle piece of a sperm contains numerous
Thus (c) is correct option.
mitochondria, which are organelles responsible for
producing energy in the form of ATP (adenosine 39. The middle piece of sperm provides
triphosphate). This energy is necessary to power (a) energy (b) nucleus
the tail (flagellum) of the sperm for its motility, (c) locomotion (d) food
enabling it to swim toward the egg for fertilization.
Thus (b) is correct option. Ans : COMP 2016

The middle piece of the sperm contains a high

36. Ovulation occurs concentration of mitochondria, which are
(a) at the beginning of menstrual cycle responsible for producing energy in the form of
(b) at the end of the menstrual cycle ATP. This energy is crucial for the movement of
(c) during any time of the menstrual cycle the sperm's tail (flagellum), allowing it to swim
(d) in the mid of the menstrual cycle and reach the egg for fertilization.
Ans : SQP 2009 Thus (a) is correct option.
Ovulation typically occurs around the middle of 40. What is true of gametes?
the menstrual cycle, usually about 14 days before (a) they give rise to gonads
the start of the next period in a 28-day cycle. (b) they are diploid
During ovulation, a mature egg is released from (c) they produce hormones
the ovary, and this is the time when a woman is (d) they are haploid
most fertile. The luteinizing hormone (LH) surge
triggers ovulation, and the egg is then available Ans : MAIN 2020

for fertilization by sperm. Gametes (sperm in males and eggs in females) are
Thus (d) is correct option. haploid, meaning they contain half the number
of chromosomes (n) compared to somatic (body)
37. The gland whose secretion neutralize the acidity cells, which are diploid (2n). This ensures that
of the urethra and vagina when fertilization occurs, the resulting zygote has
(a) semmal vericle the correct diploid number of chromosomes, with
(b) cowper’s gland one set from each parent.
(c) seminiferous tubules Thus (d) is correct option.
(d) prostrate gland
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 353

10. The gland whose secretion neutralize the acidity of oxygen, nutrients, and waste products between
of the urethra and vagina the mother's blood and the fetus, ensuring proper
(a) semmal vericle development
(b) prostrate gland Thus (b) is correct option.
(c) cowper’s gland
(d) seminiferous tubules 14. Fertilization of an ova takes place in the
(a) fallopian tubes (b) uterus
Ans : MAIN 2014
(c) vagina (d) ovary
The Cowper’s gland (also called bulbourethral Ans : COMP 2017
gland) secretes a clear fluid that helps neutralize
the acidity of the urethra in males and the vagina, Fertilization typically takes place in the fallopian
ensuring that sperm can survive and move more tubes, where the sperm meets the egg after
easily during reproduction. ovulation. The fertilized egg then moves to the
Thus (b) is correct option. uterus for implantation and further development.
Thus (a) is correct option.
11. The structure in the male reproductive system
that corresponds to oviduct of the female system 15. Which of the following is not a part of the female
is reproductive system in human beings?
(a) Vas deferens (a) Uterus (b) Ureter
(b) epididymis (c) Ovary (d) Fallopian tube
(c) seminiferous tubule Ans : MAIN 2013
(d) urethra
The ureter is not part of the female reproductive
Ans : SQP 2010 system. It is a tube that connects the kidneys
The vas deferens in males corresponds to the to the bladder, carrying urine. The reproductive
oviduct (fallopian tube) in females. It transports system includes organs like the uterus, ovaries,
sperm from the epididymis to the urethra during and fallopian tubes, which are involved in
ejaculation, similar to how the oviduct carries the reproduction.
egg from the ovary to the uterus. Thus (b) is correct option.
Thus (a) is correct option.
16. The twins formed from a single ovum and fertilised
12. Which one of the following is the correct route by a single sperm are called
that a sperm follows when it leaves the testis of (a) fraternal twins (b) homologous twins
a mammal? (c) identical twins (d) none of the above
(a) Epididymis " vas deferens " urethra Ans : SQP 2002
(b) Vas deferens " epididymis " urethra
Identical twins are formed when a single ovum is
(c) Urethra " epididymis " vas deferens
fertilized by a single sperm and then splits into
(d) Epididymis " urethra " vas deferens
two embryos. These twins share the same genetic
Ans : MAIN 2010 material and are of the same sex, making them
After sperm is produced in the testis, it is stored identical in appearance.
and matures in the epididymis. From there, it Thus (c) is correct option.
moves through the vas deferens and then into
17. Which of the following is not a part of the female
the urethra, from where it is eventually expelled
reproductive system in humans?
during ejaculation.
(a) Ovary (b) Uterus
Thus (a) is correct option.
(c) Fallopian tube (d) Vas deferens
13. A vital connection between mother and foetus is Ans : COMP 2004
called
The vas deferens is part of the male reproductive
(a) uterus (b) placenta
system, responsible for transporting sperm
(c) embryo sac (d) amniotic bag
from the epididymis to the urethra. The ovary,
Ans : COMP 2002 uterus, and fallopian tube are part of the female
The placenta is the vital connection between the reproductive system.
mother and the fetus. It facilitates the exchange Thus (d) is correct option.
CH 11 : THE REPRODUCTIVE SYSTEM

90. A hollow pear-shaped muscular organ where DIRECTION : Choose the right option :
embryo develops.
Ans : COMP 2000
100. Fertilization of human egg normally occurs in the
(uterus, fallopian tube, vagina)
Uterus
Ans : SQP 1996
91. A female gonad responsible for the production of Fallopian tube
ova.
Ans : MAIN 2006
101. The (epididymis, vas deferens, seminal vesicle)
store sperms.
Ovary
Ans : MAIN 2000
92. The male hormone produced by the interstitial Epididymis
cells.
Ans : SQP 2008
102. Sterilization in females involves cutting and tying
the (ureter, uterus, urethra, oviduct).
Testosterone
Ans : SQP 2000
93. The hormone that stimulates development of Oviduct
secondary sexual characters in males.
Ans : MAIN 2017
103. The site of fertilization in human female is
(vagina, oviduct, uterus).
Testosterone
Ans : SQP 2001
94. The hormone that stimulates contraction of Oviduct
uterus during child birth.
Ans : COMP 2018
104. The onset of menstruation in the female is
termed (Ovulation, menarache, menopause,
Oxytocin parthenogenesis).
95. The structure formed after the release of ovum Ans : COMP 2009
from Graafian follicle. Menarche
Ans : SQP 2013

Corpus luteum DIRECTION : Copy and complete the following by

filling in the blanks 1 to 5 with appropriate words:
96. The structure formed by the villi of the foetus
and the uterus of the mother. 105. The human female gonads are ovaries. A
Ans : MAIN 2023 maturing egg in the ovary is present in a sac of
Placenta cells called______(1) As the egg grows larger,
the follicle enlarges and gets filled with a fluid
97. The part of the female reproductive system where and is now called the______(2) follicle. The
fertilisation takes place. process of releasing the egg from the ovary is
called______(3). The ovum is picked up by
Ans : SQP 2017
the oviducal funnel and fertilization takes place in
Fallopian tube the______(4). In about a week the blastocyst
gets fixed in the endometrium of the uterus and
98. The male reproductive cells of mammals. this process is called______(5).
Ans : MAIN 2010
Ans : MAIN 2014
Sperms (1) Graafian follicle
99. Name the substances which the foetus receives (2) Corpus luteum
from the mother through the placenta. (3) Ovulation
(4) Oviducal funnel
Ans : SQP 2020 (5) Implantation.
Oxygen, glucose, amino acids, etc.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 355
Ans : SQP 2020
The fertilized egg is technically called a zygote. It
The placenta is the structure that connects the is the first stage of development after the sperm
fetus to the mother. It allows the exchange of fertilizes the egg, and it eventually divides and
nutrients, oxygen, and waste products, ensuring develops into a morula, then an embryo.
the proper development of the fetus throughout Thus (c) is correct option.
pregnancy.
Thus (d) is correct option. 30. The fraternal twins are
(a) of same sex
26. Testes produce the hormone (b) one boy and one girl
(a) testosterone (b) oxytocin (c) either sex
(c) progesterone (d) oestrogen (d) any of the above
Ans : COMP 2000 Ans : MAIN 2011

The testes produce the hormone testosterone, Fraternal twins can be of any sex combination
which is responsible for the development of male because they are formed from two separate eggs,
secondary sexual characteristics, such as increased each fertilized by a different sperm. They can
muscle mass, facial hair, and a deeper voice, as both be boys, both girls, or one boy and one girl.
well as sperm production. Therefore, fraternal twins can be of the same sex
Thus (a) is correct option. or different sexes.
Thus (d) is correct option.
27. Seminal plasma, the fluid part of semen is not
contributed by 31. Finger-like projections of the oviduct funnel are
(a) seminal vesicle called
(b) prostate (a) fimbriae (b) cilia
(c) bulbourethral gland (c) cervix (d) clitoris
(d) urethra Ans : SQP 2019
Ans : SQP 2006
The fimbriae are the finger-like projections at the
The urethra does not contribute to the production end of the oviduct (fallopian tube) that help guide
of seminal plasma; it merely serves as a passage the released egg from the ovary into the fallopian
for semen and urine. Seminal plasma is mainly tube during ovulation. They play a key role in the
produced by the seminal vesicles, prostate gland, process of fertilization.
and bulbourethral glands to nourish and protect Thus (a) is correct option.
sperm.
Thus (d) is correct option. 32. The middle piece of sperm has
(a) golgi body (b) ER
28. In female after how much time after fertilisation (c) ribosome (d) mitochondria
does the fertilised egg get implanted in the uterine Ans : MAIN 2021
wall ?
(a) few months (b) one month The middle piece of sperm contains mitochondria,
(c) about seven days (d) three weeks which generate the energy required for the
movement of the sperm. This energy enables the
Ans : MAIN 2010
sperm to swim toward the egg for fertilization.
The fertilized egg, or zygote, typically implants Thus (d) is correct option.
in the uterine wall about seven days after
fertilization. This process allows the embryo to 33. Which of the following is a primary sex organ?
start developing as it attaches to the nutrient-rich (a) vas deferens
uterine lining. (b) seminal vesicles
Thus (c) is correct option. (c) prostate
(d) testis
29. The technical term for the fertilized egg is Ans : COMP 2001
(a) placenta (b) morula
(c) zygote (d) embryo The testis is the primary sex organ in males,
responsible for producing sperm and the hormone
Ans : COMP 2015
testosterone. The other structures, such as the
CH 11 : THE REPRODUCTIVE SYSTEM

(a) Assertion is True and Reason is False approximately halfway through the cycle. This is
(b) Assertion is False and Reason is True the time when the ovary releases a mature egg,
(c) Both Assertion and Reason are True ready for fertilization.
(d) Both Assertion and Reason are False Thus (c) is correct option.
Ans : SQP 2025
6. The technical term for the fertilized egg is
Thus (c) is correct option. (a) placenta (b) zygote
(c) morula (d) embryo
3. A zygote which has Y chromosome inherited from
the father will develop into a: Ans : SQP 2010

(a) Will depend on the chromosome inherited The zygote is the technical term for the fertilized
from the mother egg, formed when a sperm cell from the male
(b) Girl fertilizes an egg cell from the female. It is the first
(e) Either boy or a girl cell of a new organism and undergoes multiple
(d) Boy divisions to eventually form the embryo.
Thus (b) is correct option.
Ans : MAIN 2024

In humans, the presence of a Y chromosome in 7. A single highly coiled tube where sperms are
the zygote will develop into a male child. The stored, gets concentrated and mature is
sperm carries either an X or a II chromosome, (a) Epididymis (b) Vas efferentia
while the egg always carries an X chromosome. (c) Vas deferens (d) Seminiferous tubule
If the sperm carryingan X chromosome fertilises Ans : COMP 2015
the egg, the resulting zygote will be XX, leading
to the development of a female child. Conversely, The epididymis is a long, coiled tube where sperm
it the sperm carrying a Y chromosome fertilises is stored, concentrated, and allowed to mature
the egg, the zygote will be XY, resulting in the after being produced in the seminiferous tubules.
development of a male child. This maturation process is essential for the sperm
Thus (d) is correct option. to gain motility and fertilizing capability.
Thus (a) is correct option.
4. A biology teacher explains that in human males,
sperm cells determine the sex of the offspring 8. The surgical method of sterilization in women
because each sperm carries only one type of sex involves the cutting and tying of :
chromosome. In a human male, a sperm will (a) Ureter (b) Oviduct
contain : (c) Urethra (d) Uterus
(a) Both X and Y chromosomes Ans : SQP 2005
(b) Only Y chromosome
In women, the surgical sterilization procedure,
(c) Only X chromosome
known as tubal ligation, involves the cutting and
(d) Either X or Y chromosome
tying of the oviducts (also called fallopian tubes).
Ans : MAIN 2019 This prevents eggs from traveling from the ovaries
In human males, sperm cells carry either an X or to the uterus, effectively preventing fertilization
a Y chromosome, not both. This determines the and pregnancy.
sex of the offspring, as an X chromosome from Thus (b) is correct option.
the sperm will result in a female (XX), and a Y
9. Fertilization takes place in
chromosome will result in a male (XY).
(a) uterus (b) oviduct
Thus (a) is correct option.
(c) cervix (d) ovary
5. On which day of the menstrual cycle does Ans : MAIN 2008
ovulation take place ?
Fertilization typically occurs in the oviduct (also
(a) 5th day (b) 28th day
known as the fallopian tube). This is where
(c) 14 day
th
(d) 1st day
the sperm meets and fertilizes the egg, forming
Ans : COMP 2019 a zygote. The fertilized egg then travels to the
In a standard 28-day menstrual cycle, ovulation uterus for implantation.
generally happens around the 14th day, which is Thus (b) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 357

41. A single highly coiled tube where sperms are 45. Fertilisation is the process of fusion of male
stored, get concentrated and mature is known as gamete and the female gamete to produce a/an
(a) vas efferentia (a) embryo (b) zygote
(d) epididymis (c) infant (d) child
(c) vas deferens
Ans : SQP 2000
(d) seminiferous tubule
Fertilization results in the formation of a zygote,
Ans : SQP 2022
which is the first cell of a new organism. The
The epididymis is a long, coiled tube located zygote undergoes cell divisions and develops into
behind the testes. It plays a crucial role in storing, an embryo, eventually leading to the formation
concentrating, and allowing the sperm to mature. of a fetus.
Sperm gain motility and the ability to fertilize an Thus (b) is correct option.
egg during their time in the epididymis.
Thus (b) is correct option. 46. A single highly coiled tube where sperms are
stored and get matured is known as
42. Fertilization takes place in (a) vasa efferentia
(a) fimbriae (b) uterus (b) epididymus
(c) vagina (d) oviduct (c) vas deferens
(d) seminiferous tubules
Ans : MAIN 2023

Fertilization, the fusion of a sperm and an egg, Ans : MAIN 2007

typically occurs in the oviduct (also known as The epididymis is a long, coiled tube located
the fallopian tube). After ovulation, the egg is behind the testes. It is responsible for storing,
released into the oviduct, where it meets the concentrating, and allowing the sperm to mature,
sperm, leading to fertilization. The fertilized egg gaining motility and the ability to fertilize an egg.
then moves toward the uterus for implantation. Thus (b) is correct option.
Thus (d) is correct option.
47. The onset of menstruation in the female is
43. At which of the following stages the implantation (a) Menarche (b) Ovulation
in uterus takes place? (c) Menopause (d) Parturition
(a) 8 cell stage (b) morula
Ans : COMP 2019
(c) blastocyst (d) late gastrula
Thus (c) is correct option.
Ans : COMP 2014

Implantation occurs when the blastocyst, a hollow 48. The onset of menstruation in the female is
ball of cells formed after fertilization, attaches (a) Ovulation (b) Menopause
itself to the lining of the uterus. This stage occurs (c) Menarche (d) Parturition
around 5-7 days after fertilization. The blastocyst Ans : MAIN 2001
consists of an outer layer of cells (trophoblast)
Thus (c) is correct option.
that will help form the placenta and an inner cell
mass that will develop into the embryo. 49. In the human menstrual cycle, the ovulation
Thus (c) is correct option. occurs around
(a) day 10 (b) day 24
44. Vas deferens is a part of a
(c) day 1 (d) day 14
(a) testis (b) epididymus
(c) duct system (d) accessory glands Ans : SQP 2006

Ans : MAIN 2008 Thus (d) is correct option.

The vas deferens is a tube that is part of the male 50. The external female genitalia is known as
reproductive duct system. It transports mature (a) vagina (b) uterus
sperm from the epididymis to the urethra during (c) cervix (d) vulva
ejaculation. The duct system also includes the
epididymis and ejaculatory ducts, which work Ans : MAIN 2011

together to store, transport, and deliver sperm. Thus (d) is correct option.
Thus (c) is correct option.
CH 11 : THE REPRODUCTIVE SYSTEM

18. Given below is a statement or question followed Parturition refers to the process of giving birth,
by four choices. Select and rewrite the correct and implantation is the attachment of the embryo
answer to the given statement. to the uterine wall.
The onset of menstruation in the female is termed Thus (c) is correct option.
as
(a) ovulation (b) parthenogenesis 22. In the human menstrual cycle, the ovulation
(c) menopause (d) menarche occurs around
(a) day 14 (b) day 24
Ans : SQP 2018
(c) day 10 (d) day 1
Menarche refers to the first occurrence of Ans : MAIN 2001
menstruation, marking the beginning of a
female’s reproductive years. Menopause is when Ovulation typically occurs around day 14 of a
menstruation ceases, ovulation is the release of 28-day menstrual cycle. This is the time when a
an egg, and parthenogenesis is a form of asexual mature egg is released from the ovary, ready for
reproduction. potential fertilization.
Thus (d) is correct option. Thus (a) is correct option.

19. Gestation period of human is 23. Which of the following is not true for the process
(a) 250 days (b) 280 days of ovulation in human?
(c) 170 days (d) 140 days (a) The egg is released from Graafian follicle
(b) The fertilised egg passes out of female’s body
Ans : MAIN 2023
(c) The egg is fertilised in Fallopian tube
The gestation period of humans is approximately (d) The egg passes through fimbriated funnel of
280 days, which is around 9 months, the time it Fallopian tube
takes for a baby to fully develop from conception Ans : SQP 2016
to birth.
Thus (b) is correct option. During ovulation, the egg is released from the
Graafian follicle in the ovary, passes through the
20. In a biology class, students learn that fertilization fimbriated funnel of the fallopian tube, and can
in humans occurs in a specific part of the female be fertilized in the fallopian tube. However, if the
reproductive system. In humans, the fertilisation egg is fertilized, it does not pass out of the body
take place in : but implants in the uterus for development.
(a) uterus (b) oviducal funnel Thus (b) is correct option.
(c) vagina (d) fallopian tube
24. Sperms are produced in
Ans : COMP 2020
(a) seminiferous tubules
In humans, fertilization typically occurs in the (b) epididymus
fallopian tube. After ovulation, the egg travels (c) vasa efferentia
into the fallopian tube, where it may meet the (d) leydig cells
sperm and undergo fertilization before moving to Ans : MAIN 2005
the uterus for implantation.
Thus (d) is correct option. Sperms are produced in the seminiferous tubules
of the testes. These tubules are responsible for
21. The period of intrauterine development of the the process of spermatogenesis, where sperm
embryo is known as cells are developed. The epididymus stores and
(a) embryonic development matures the sperm, while Leydig cells produce
(b) parturition testosterone, but they do not produce sperm.
(c) gestation period Thus (a) is correct option.
(d) implantation
25. The association between the foetus and mother
Ans : SQP 2014
is called
The gestation period refers to the time of (a) embryonic membrane
intrauterine development from fertilization until (b) amnion
birth. It is the period during which the embryo (c) chorion
and fetus grow inside the mother's uterus. (d) placenta
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 359

68. Non-identical twins produced by the fertilization 79. The fully developed part of ovary containing
of two eggs. mature egg.
Ans : MAIN 2010 Ans : MAIN 2021

Fraternal twins Graafian follicle

69. The structure formed after release of ovum from 80. The accessory gland in human male whose
graafian follicle. secretion activates the sperms.
Ans : COMP 2021 Ans : COMP 2023

Corpus luteum Seminal vesicle

70. A fluid surrounding the developing embryo. 81. The tubular knot fitting like a cap on the
upperside of the testis.
Ans : MAIN 2023
Ans : SQP 2006
Amniotic fluid
Epididymis
71. The mucous membrane lining the uterus.
82. The period for which the foetus remains inside
Ans : SQP 2013
the uterus.
Endometrium Ans : MAIN 2009

72. Two accessory glands of the male reproductive Gestation

system.
83. The process of delivery of child.
Ans : MAIN 2019
Ans : MAIN 2014
Prostate and Cowper’s gland
Parturition
73. The tubular knot fitting like a cap on the upper
84. The site of production of sperm in man.
surface of the testes.
Ans : COMP 2019
Ans : MAIN 2005
Testis
Epididymis
85. The term used for the stoppage of menstruation.
74. The onset of menstrual cycle in young females.
Ans : MAIN 2004
Ans : SQP 2002
Menopause
Menarche
86. The process of fusion of male and female gametes.
75. The membrane that surrounds the foetus and
secretes a protective fluid. Ans : COMP 2016

Ans : COMP 2009 Fertilisation

Amnion 87. A muscular wall into which the testis descend.
76. The female copulatory organ. Ans : SQP 2019

Ans : MAIN 2011

Scrotal sac

Vagina 88. The innermost foetal membrane which secretes

amniotic fluid.
77. The male copulatory organ.
Ans : SQP 2015
Ans : SQP 2016
Amnion
Penis
89. Two substances that diffuse out of the foetus into
78. The structure that produces testosterone. the placenta.
Ans : SQP 2019 Ans : MAIN 2003

Testis CO2, urea

CH 11 : THE REPRODUCTIVE SYSTEM

51. Fertilization takes place in Ans : SQP 2025, 2024

(a) uterus (b) oviduct Umbilical Cord

(c) vagina (d) fimbriae
58. The process of attachment of fertilized ovum to
Ans : COMP 2016
uterine wall.
Thus (b) is correct option.
Ans : SQP 2024, 2000

52. Gestation period of human is Implantation

(a) 140 days (b) 250 days
(c) 170 days (d) 280 days 59. The organ in which foetus develops in a
mammalian female.
Ans : SQP 2013
Ans : MAIN 1996
Thus (d) is correct option.
Uterus
53. The life of corpus kiteums if pregnancy does not
occur is 60. The male reproductive cells of mammals.
(a) 14 days (b) 15 days Ans : SQP 1997
(c) 20 days (d) 28 days
Spermatozoa/sperms
Ans : MAIN 2016
61. The part of female reproductive system where
Thus (d) is correct option.
fertilization takes place.
54. The middle piece of sperm has Ans : MAIN 2010 1999
(a) mitochondria (b) golgibody
Oviduct
(c) ribosome (d) ER
Ans : SQP 2021 62. The cells of testes that produce male hormones.
Thus (a) is correct option. Ans : SQP 2011

Leydig Cells/ Interstitial Cells

55. The structure in the male reproductive system
that corresponds to oviduct of the female system is 63. The fluid surrounding the developing embryo.
(a) seminiferous tubule
(b) epididymis Ans : COMP 2000

(c) urethra Amniotic fluid

(d) vas deferens
64. The structure in which testes are present in man.
Ans : COMP 2014
Ans : MAIN 2002
Thus (d) is correct option.
Scrotum
56. The onset of menstruation is
(a) menarche (b) ovulation 65. The period of intrauterine development of embryo.
(c) menopause (d) parthanogenies Ans : SQP 2003

Ans : SQP 2018 Gestation

Thus (a) is correct option.
66. The canal through which testes descend into
scrotum just before birth in a human male child.
Ans : MAIN 2004

ONE MARK QUESTIONS Inguinal canal

67. The pituitary hormone wswhich stimulates

contraction of uterus during child birth.
DIRECTION : Name the following :
Ans : SQP 2017

57. The structure that connects placenta and the Oxytocin

human foetus.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 361

DIRECTION : True or false : 115. Fertilization takes place in uterus.

Ans : COMP 2019
106. Gestation is the process of fixing the Zygote to
Uterine wall. False

Ans : SQP 2011 116. Twelve mature eggs are typically produced by
False (Implantation) each ovary of a non-pregnant woman in a year.
Ans : SQP 2017
107. Tubectomy involves the cutting and tying of vas
deferens in male. False

Ans : SQP 1996 117. The female equivalent of the glans of the penis is
False hymen.
Ans : MAIN 2014
108. Pregnancy in women can be prevented by the
method of vasectomy. False.

Ans : MAIN 1997 118. Ovulation is the release of sperms from the testis.
False Ans : SQP 2018

109. Fertilization is the product of fusion of egg nucleus False

and sperm nucleus.
119. Vagina is a muscular tube.
Ans : SQP 2004
Ans : COMP 2017
True
True
110. Fertilization of ova in human female occur in the
120. There is mixing of blood between mother blood
vagina.
and the foetus.
Ans : MAIN 1992
Ans : MAIN 2020
False
False
111. The number of ova produced after a primary
121. Fertilization occurs in the uterus.
oocyte has undergone two maturation divisions
is 4. Ans : COMP 2023

Ans : COMP 2010 False

False 122. The enlarged mature follicle bursts to release the
egg.
112. Gametes are usually produced in specialized
structure called gonads. Ans : SQP 2018

Ans : SQP 2017 True

True 123. Placenta produces certain hormones.
113. Seminal vesicles contribute to the fluid substance Ans : COMP 2022

of the seminal fluid. True

Ans : MAIN 2023
124. Mother’s blood flows into the foetus through
True placenta.
114. Endometrium is highly vascular and rich in Ans : MAIN 2000

glands. True
Ans : SQP 2020
125. Gestation in humans is completed in about 380
True days.
CH 11 : THE REPRODUCTIVE SYSTEM

192. Some women have facial hair like beard and Ans : SQP 2011

moustache. Give reason. Oestrogesn, progesterone and relaxin.

Ans : COMP 2017
202. What is Placenta ?
The development of facial hair like beard and
moustache in some woman is due to the overgrowth Ans : COMP 2018

of adrenal cortex which produces cortisone. This A spongy tissue composed of embryonic and
condition is known as adrenal virilism. maternal tissue.
193. What is the significance of amniotic fluid? 203. What are the three major parts of a developing
Ans : SQP 2015
embryo ?

Ammiotic fluid protects the foetus from Ans : MAIN 2014

mechanical injuries. Embryonic disc, amnion and yolk sac.

194. What are the four major parts of the male 204. What is colostrums ?
reproductive system ?
Ans : SQP 2013
Ans : SQP 2020
It is a thin milky secretion from the nipples
Testes, ducts, accessory glands and penis. produced before and just after child birth.
195. How many days are required for the maturation 205. What is colostrums rich in ?
of sperms ?
Ans : COMP 2002
Ans : MAIN 2010
It is rich in antibodies, proteins and vitamins.
About 10 to 14 days.
206. How long does the sperms take to become mature?
196. What structure lines the fallopian tube internally?
Ans : SQP 2021
Ans : SQP 2008
10 to 14 days.
Ciliated epithelium.
207. How does placenta acts as an endocrine gland?
197. What is ejaculatory duct ?
Ans : MAIN 2023
Ans : COMP 2005
Placenta secretes oestrogen and progesterone
The terminal part of the seminal duct formed by hormone.
the union of vas deferens and secretory duct of
the seminal vesicle is called ejaculatory duct. 208. What is sperm lysin ?
Ans : COMP 2020
198. What are fallopian tubes ?
The acrosomes release chemicals called as lysins
Ans : MAIN 2002
which help in breaking the cell clusters around
These are pair of slender ducts opening on either the mature ovum.
side into the uterus.
209. Define the term implantation.
199. What is vulva ?
Ans : MAIN 2022
Ans : SQP 2000
It is the process of attaching the zygote into the
It is the external female genitalia. uterus wall of the mother.
200. What are the components of vulva ? 210. What is inguinal hernia?
Ans : COMP 2001 Ans : SQP 2013

Labia majora, labia minora, clitoris, vestibule, It is the protrusion of small intestine into the
pons pubis. scrotal sacs.
201. What are the hormones secreted by corpus 211. What is meant of gestation period ?
luteum?
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 363

143. Corpus luteum. Ans : SQP 2006

Ans : MAIN 2016

Ovulation, fertilization, implantation, gestation.

Secrete progesterone hormone. 153. Vagina, ovary, uterus, oviduct, cervix, (pathway
of egg after ovulation)
144. Leydig cells.
Ans : MAIN 2010
Ans : SQP 2016
Ovary, oviduct, uterus, vagina, cervix.
Secrete male sex hormones called Testosterone.

145. Seminal Vesicles. DIRECTION : Differentiate between the following :

Ans : SQP 2019
154. Structure of sperm and structure of ovum.
Produces secretion which serves as a mediums for
transportation of sperms which forms semen. Ans : MAIN 2003

146. Prostate gland Sperm Ovum

Ans : MAIN 2013 Motile, consists of Non-motile and round
head, neck, middle in structure.
To produce an alkaline fluid that is a part of
piece and tail.
semen.
155. Prostate and cowpers gland (nature of secretion)
DIRECTION : Structure and functional activity of
Ans : COMP 2004

147. Corpus luteum and______ Prostate gland Cowper’s gland

Ans : SQP 2000 Alkaline and neutralizes Secretion serves as
Seminiferous tubules and sperms. acidic nature of female lubricant.
reproductive tract.
148. Seminiferous tubules and______
156. Corpus callosum and corpus luteum (function).
Ans : COMP 2010

Seminiferous tubules and sperms. Ans : MAIN 2014

Corpus callosum Corpus luteum

DIRECTION : Write in logical sequence :
Connects the two Secretion of
cerebral hemispheres. progesterone hormone.
149. Implantation, ovulation, childbirth, gestation,
fertilization.
157. Implantation and gestation (definition)
Ans : SQP 2001
Ans : SQP 2005
Ovulation, fertilization, implantation, gestation,
childbirth.
Implantation Gestation
150. Sperm duct, penis, testis, sperms, semen. Fixing of embroyo Full term of development
Ans : MAIN 2006, 2001
on the wall of of embryo in uterus
uterus. (about 280 days).
Testis, sperms, sperm duct, semen, penis

151. Graafian follicle, ostium, ovum, uterus, fallopian 158. Sperm duct and fallopian tube (function)
tube Ans : COMP 2016

Ans : COMP 2005

Sperm duct Fallopian tube
Graafian follicle, ovum, ostium, fallopian tube,
uterus. Sperm duct transports Fallopian
sperms from the epididymis tube is site of
152. Implantation, fertilization, ovulation, gestation. into the urethra. fertilization.
CH 11 : THE REPRODUCTIVE SYSTEM
Ans : SQP 2014
DIRECTION : Give the functions :
False
135. Testis
126. Pregnancy in women can be prevented by
vasectomy. Ans : MAIN 1996

Ans : MAIN 2016

Produces sperms and male sex hormone
testosterone.
False
136. Scrotum
127. Sperm is a single cell.
Ans : MAIN 1999
Ans : SQP 2014
Keeps testis at a lower temperature (2°C less than
True body temperature) thus favouring maturation of
sperms.
128. One egg is released from each of the two ovaries
every month.
137. Placenta
Ans : MAIN 2018
Ans : SQP 2004, 1999
False
Transfers nutrients, oxygen and antibodies from
129. Menopause is the stoppage of menstruation. maternal blood to foetal blood, and removes
metabolic wastes. Also acts as an endocrine gland.
Ans : SQP 2022

True 138. Acrosome

130. Amniotic fluid acts as a shock absorber. Ans : COMP 2000

Ans : SQP 2023 Entry of sperm into egg is facilitated by release

of certain lysosomal enzyme by the acrosome on
True
the head of sperm.
131. Sperms are produced at body temperature.
139. Amniotic fluid
Ans : MAIN 2010
Ans : MAIN 2004
False
Protects the developing embryo from shocks and
injuries.
DIRECTION : Pick the odd one in following :
140. Amnion
132. Ovary, fallopain tube, ureter, uterus.
Ans : SQP 2005
Ans : SQP 2000
Encloses the embryo by forming amniotic cavity
Ureter which is filled with clean lymph like fluid which
cushions and protects the embryo from shock.
133. Cowper’s gland, Urethral gland, Lachrymal gland,
Seminal vesicles, Prostrate gland. 141. Seminiferous tubule.
Ans : MAIN 2010 Ans : COMP 2006, 1992

Male accessory glands It is lined internally by germinal epithelium. Some

Lachrymal gland of these epithelial cells function as spermatogonia
and give rise to sperms.
134. Prostate gland, Cowper’s gland, seminal vesicle,
seminiferous tubules. 142. Corpus luteum
Ans : SQP 2018 Ans : SQP 2009

Odd term – Seminiferous tubule, Corpus luteum secretes estrogen and progesterone
Category – Accessory glands of male reproductive to prepare the uterus for receiving the embryo.
system Secretion of progesterone.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 365

175. The fluid which surrounds the foetus. Located between the posterior surface of the
urinary bladder and the rectum.
Ans : COMP 2018

Amniotic fluid
DIRECTION : Correct and rewrite the statement by
176. Fixing of developing zygote on the uterine wall. changing the biological term that is underlined for
each statement:
Ans : MAIN 2015

Implantation 186. The protective sac which develops around the

developing embryo is called the Pericardium.
177. The permanent stoppage of menstruation at
about the age of 45 years in a female. Ans : COMP 2019

Ans : COMP 2015 The protective sac which develops around the
developing embryo is called amnion.
Menopause

178. A method of contraception in which the sperm DIRECTION : Explain the following term :
duct is cut and ligated.
Ans : SQP 2014 187. Parturition.
Vasectomy. Ans : SQP 2009

Parturition is the act of expelling the full term

DIRECTION : Give the exact location : foetus from the mothers’ uterus at the end of
gestation. It is also called as child birth.
179. Amnion
Ans : MAIN 2014, 2011 DIRECTION : Answer the following :
Membrane, covering the liquid around the foetus
188. What is the significance of Testes being placed in
in the uterus.
Scrotal sacs?
180. Prostate gland. Ans : SQP 2025

Ans : SQP 2017 To maintain an ideal temperature of 2 to 3° C less

Inferior to urinary bladder encircling urethra. than body temperature for survival of sperms.

181. Testis 189. What is Parthenocarpy? Give one example.

Ans : MAIN 2019 Ans : SQP 2025

Inside Scrotum It is development of fruits without fertilization.

Apples, tomatoes etc.
182. Amniotic fluid
190. What is the role played by the inguinal canal?
Ans : SQP 2018
Ans : MAIN 2013
Cavity between amnion and embryo
Inguinal canal allows the testis to desend to the
183. Epididymis scrotum.
Ans : COMP 2018
191. Give biological explanations for the following :
A knot like structure in the upper portion of testes The placenta is an important structure for the
development of a foetus.
184. Seminiferous tubule
Ans : SQP 2018
Ans : MAIN 2012
Placenta allows diffusion of substances like
Located in the testis. oxygen, CO2, hormones, nutrients, excretory
products, etc. from the mother to the foetus or
185. Seminal vesicle
from foetus to the mother.
Ans : SQP 2014
CH 11 : THE REPRODUCTIVE SYSTEM

159. Testosterone and Oestrogen [organ which secretes. Menopause

Ans : MAIN 2014
165. The period of complete intrauterine development
Testosterone – Testes of the embryo.
Oestrogen – Ovary Ans : SQP 2005

160. Tubectomy and Vasectomy. Gestation period

Ans : MAIN 2015
166. Non-identical twins produced by the fertilization
of two eggs.
Tubectomy Vasectom
Ans : MAIN 2008
Fallopian tube is cut Vas deferens is cut
and stitched so that and both ends are tied Fraternal twins
fertilization does not to stop the flow of 167. Membrane that protects the foetus and secretes a
take place. sperm. protective fluid.

161. Prostrate gland and Cowper’s gland (the nature Ans : COMP 2010

of secretion). Amnion
Ans : SQP 2010
168. The onset of menstruation in a young girl.

Prostrate gland Cowper’s gland Ans : SQP 2013

Prostrate gland secretes Cowper’s gland’s Menarche

an alkaline secretion secretion acts as a 169. Structure which connects the placenta with the
which neutralises the lubricant. foetus.
acid in the vagina
Ans : MAIN 2016

162. Gestation and Parturition. Umbilical cord

Ans : SQP 2022
170. The canal through which the testes descend into
the scrotum just before the birth of a male baby.
Gestation Parturition
Ans : COMP 2016
It is the total time It is the process of
period in which an child birth after the Inguinal canal
embryo develops fully gestation period. 171. The structure formed by the villi of the embryo
inside the uterus. and the uterus of the mother.

163. Graafian follicle and Corpus luteum. Ans : MAIN 2015

Ans : SQP 2016

Placenta.

172. The accessory gland in human males whose

Graafian Follicle Corpus Luteum secretion activates the sperms.
It is a fully It is a yellow mass formed Ans : COMP 2017
developed ovarian after the release of an
follicle containing a egg from the Graafian Seminal vesicles
mature ovum. follicle which acts as an 173. The kind of twins formed from two fertilised eggs.
endocrine gland.
Ans : SQP 2017

Non-identical/Fraternal
DIRECTION : Give biological term :
174. The onset of menstruation in a young girl.
164. Cessation of menstruation in females.
Ans : SQP 2018
Ans : COMP 1996
Menarche
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 367
Ans : SQP 1997
DIRECTION : Complete the following :
The interval of time between implantation and
birth is called gestation period. 218. An accessory reproductive gland that secretes an
alkaline fluid is______.
212. Write the functions of uterus.
Ans : COMP 2010
Ans : SQP 2002
prostrate gland
It is a sac where embryo develops. Amnion
contains amniotic fluid which protect the embryo 219. The part of the ovary that secretes progesterone
from shocks and jerks. is______.
Ans : SQP 2007
213. At the time of birth, how many follicles does a
baby female have and how many does a matured corpus luteum
human female have?
220. The part of the uterus that thickness each month
Ans : MAIN 2019 in preparation for pregnancy is______.
8,00,000 follicles at time of birth. 400 mature to Ans : MAIN 2009
discharge ova while others degenerates. endometrium
214. What is the significance of amniotic fluid ? 221. Gestation period in human female is______
Ans : SQP 2015 days.
Acts like cushion and protects embryo from shock Ans : COMP 2015
and injury. Does not allow sticking of embryo 280 days
with amnion.
222. ______nourishes the embryo inside the womb.
215. What are secondary sexual characters?
Ans : MAIN 2000
Ans : COMP 2017
Placenta
The male and female sex show externally different
visible characteristics. These features are called 223. The period of complete development of the foetus
secondary sexual characters. till birth is called______.

216. How does CO2 and urea excreted by the foetus Ans : COMP 2006

gets rid off? gestation

Ans : MAIN 2008
224. The canal through which the testis desend into
By diffusion, the foetal blood gives off the CO2 the scrotum just before the birth of a male baby
and urea into the mother’s blood. is______.

217. Match the column I with column II : Ans : SQP 2014

Inguinal canal
Column I Column II
(a) Scrotal sac (i) Maturation of 225. The part where fertilisation occurs in human
Spermatozoa female______.
(b) Epididymis (ii) Fertilization Ans : COMP 2020

(c) Prostate gland (iii) Parturition oviduct/fallopian tube

(d) Oviduct (iv) Temperature 226. The process of development of the sperms in the
regulation testis is called______.
(e) Oxytocin (v) Alkaline fluid Ans : SQP 2003

Ans : SQP 2002 spermatogenesis

(a)-(iv), (b)-(i), (c)-(v), (d)-(ii), (e)-(iii). 227. The follicle which contains the matured ovum is
called______.
CH 11 : THE REPRODUCTIVE SYSTEM

system where the above cells are produced. 303. The figure given below represents the female
(iii) Where in the female reproductive system do reproductive system of a mammal. Parts indicated
these cells unite ? by the guidelines A to D are as follows :
(iv) Name the main hormones secreted by the (1) Give appropriate term for each of the following :
ovary (2) testes.
(v) Name an accessory gland found in the male
reproductive system and state the function of
its secretion.
Ans : SQP 2011

(i) A – Ovum
B – Spermatozoa
(ii) Follicles of ovary " ovum
Seminiferous tubules in testes " sperm
(iii) Fallopian tube
(iv) Estrogen, Progesterone
(v) Testosterone

302. The following diagram represents the ventral view (i) The onset of reproductive phase in a young
of the female reproductive system : female.
(ii) Rupture of follicle and release of ovum from
the ovary.
(iii) Monthly discharge of blood and disintegrated
tissues in human female.
(iv) Process of fusion of ovum and sperm.
(v) Fixing of developing zygote (blastocyst) on
the uterine wall.
Ans : MAIN 1998

(i) Menarche (Puberty)

(ii) Ovulation
(i) Label the parts indicated by guidelines 1 - 8. (iii) Menstrual phase, endorsement of uterus
(ii) How does the uterus prepare for the reception (iv) Fertilization
of a zygote ? (v) Implantation
(iii) What happens to the uterus if fertilization
takes place ? 304. The diagram given below is one of the system in
(iv) What happens to the uterus if fertilization the male human body :
has failed to take place ? (i) Write down the name of the organ in the
system.
Ans : MAIN 1998 (ii) Label guidelines ‘1’ to ‘5’.
(i) 1. Oviduct; 2. Funnel of oviduct : 3. Ureter; (iii) Write down the functions of guideline
4. Vagina; 5. Ovary; 6. Uterus ; 7. Urinary numbered 2 and 5.
bladder; 8. Urethra.
(ii) The wall of uterus get thickened and richly
supplied with blood capillaries to receive the
zygote.
(iii) The wall of uterus further becomes more
thickened and gets intensely supplied with
blood capillaries and the embryo is attached
to uterine wall after 7 days of fertilisation.
(iv) The endometrium breaks down and causes
discharge of blood and mucous resulting in
menstruation.
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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 369

transportation of substances from placenta to 258. Seminiferous tubules

foetus and vice versa.
Ans : SQP 2007

248. Leydig cells The site where sperm is actually produced in the
Ans : MAIN 2015
testis.

To produce testosterone. 259. Cowper’s gland

249. Sperm duct Ans : MAIN 2009

Ans : COMP 2002

To secrete a fluid which serves as a lubricant.

To transport sperms from the testis. 260. Seminal vesicle

250. Scrotal sac Ans : COMP 2011

Ans : SQP 2017

It secretes a fluid which activates the sperm.

To protect the testis and also to regulate the 261. Urethra in man
temperature of the testis for sperm production.
Ans : SQP 2014

251. Testis It is a common passage for urine and semen.

Ans : MAIN 2000

To produce the sperms. DIRECTION : Find odd one out in the following :

252. Uterus 262. Ureter, urethra, oviduct, ovary.

Ans : MAIN 2013 Ans : MAIN 2019

To protect and to provide nutrition to the ureter

developing embryo.
263. Vagina, vulva, seminal vesicle, uterus.
253. Corpus luteum
Ans : SQP 2017
Ans : SQP 2018
seminal vesicle
To act as an endocrine gland which produces
progesterone. 264. Epididymis, vas deferens, seminiferous tubule,
ovum, urethra.
254. Amniotic fluid
Ans : COMP 2012
Ans : COMP 2019
ovum
Acts as a shock absorber and protects the foetus
from mechanical shocks. 265. Fertilization, implantation, gestation, sperm,
ovum.
255. Placenta
Ans : MAIN 2020
Ans : MAIN 2023
sperm
To exchange the materials like respiratory gases,
nutrients and urea between the mother and foetus.
DIRECTION : Give reasons:
256. Epididymis
266. Twins may or may not be identical.
Ans : SQP 2001
Ans : MAIN 2010
To store the sperms.
Twins are formed according to the number of eggs
257. Amnion released in the oviduct. If two eggs are available
Ans : COMP 2004 at a time, both may get fertilised and form
fraternal twins. If the zygote of a single egg splits
To protect the embryo. and separates into two equal parts then identical
twins are formed.
CH 11 : THE REPRODUCTIVE SYSTEM
Ans : MAIN 2010 Ans : MAIN 2012

Graafian follicle seminiferous tubule

228. The process of development of ovum in the ovary

is called______. DIRECTION : State the functions of the following :

Ans : SQP 2013

238. Seminiferous tubule
oogenesis
Ans : COMP 2018

229. The process of releasing of egg from the ovary is To produce sperms.
called______.
239. Cowper’s gland
Ans : COMP 2017
Ans : SQP 2023
ovulation
To secrete a fluid which serves as a lubricant.
230. The structure of the sperm which helps to penetrate
the egg membrane of the ovum is______. 240. Acrosome

Ans : MAIN 2020 Ans : MAIN 2021

acrosome Secretes an enzyme which helps

231. The connecting link between the foetus and 241. Oviduct
placenta is called______. Ans : SQP 2019

Ans : SQP 2023 Helps to fertilize the egg.

umbilical cord
242. Amnion
232. The testosterone hormone is secreted by the Ans : MAIN 2020
______cells.
To protect the embryo.
Ans : SQP 2000
243. Placenta
interstitial
Ans : COMP 2014
233. Sperms contains ______ number of
To exchange the materials like respiratory gases,
chromosomes.
nutrients respiratory gases, nutrients and urea
Ans : MAIN 2003 between mother and foetus.
23
244. Scrotal sac
234. The shedding out of the endometrium along with Ans : MAIN 2010
blood is called______.
To protect the testes and regulate the temperature
Ans : SQP 2007 of testes for spermatogenesis.
menstruation
245. Vagina
235. The expulsion of the foetus from the mother’s Ans : SQP 2009
body is called______.
To receive the semen (sperms).
Ans : COMP 2021
246. Male urethra
parturition
Ans : MAIN 2003
236. Man is______organism.
A common passage for urine and semen.
Ans : SQP 2017
247. Umbilical cord
unisexual
Ans : SQP 2005
237. The unit of testis is______.
Connects the foetus with placenta and helps in
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 371

The Graafian follicle, after ovulation turns into a 283. State the role of testosterone.
hormone producing tissue called Corpus luteum.
Ans : COMP 2020

276. Given below are sets of five terms each. Rewrite Testosterone helps in the development of secondary
the terms in correct order in a logical sequence. sexual character such as increase in height, growth
Example : Large intestine, Stomach, Mouth, of hairs on the face etc. enlargement of genital
Small intestine, Oesophagus. organs etc.
Answer : Mouth " Oesophagus " Stomach "
Small intestine " Large intestine. 284. What is the significance of human testis being
Uterus, Parturition, Fertilisation, Gestation, located in the scrotum?
Implantation. Ans : MAIN 2006

Ans : SQP 2017 Scrotum protects the testis. It also regulates

Fertilisation, Uterus, Implantation, Gestation, the temperature of the testis. Sperms need a
Parturition. temperature less than the body temperature for
their production and development.
277. What is sexual reproduction ?
285. What is vasectomy and tubectomy?
Ans : COMP 2009
Ans : SQP 2019
The process of reproduction in which a male
gamete unites with the female gamete to form Vasectomy is the cutting and ligating of vasa
a zygote which develops into a new individual is deferentia to sterelize men for birth control.
called reproduction. Tubectomy in the cutting and ligating the
oviducts in females. This surgical methods do not
278. State the functions of testis. allow the fertilization of sperm and ova.
Ans : SQP 2003
286. What is umbilical cord?
(a) To produce sperms.
Ans : COMP 2016
(b) To produce male sex hormones.
It is cord-like structure connecting the foetus
279. State the functions of ovary. and the placenta. Through the umbilical cord
Ans : MAIN 2000
the embryo is getting glucose, oxygen and it also
removes urea, CO2, etc from the embryo.
(a) To produce the ova.
(b) To produce female sex hormones. 287. How is embryo protected inside the uterus ?

280. Where are the male and female gametes produced? Ans : MAIN 2010

Ans : SQP 2002

The embryo is surrounded by embryonic
membrane called amnion. The cavity between the
Male gametes are produced in the testis. Female foetus and amnion contains amniotic fluid which
gametes are produced in the ovaries. acts as a shock absorber. It protects the embryo
from mechanical jerks.
281. Name two surgical techniques for male and female
that are used to prevent pregnancy.
DIRECTION : Difference between them:
Ans : COMP 2018

Vasectomy – in male. 288. Menarche and menopause.

Tubectomy – in female. Ans : MAIN 2012

282. How are test tube babies formed ? Menarche Menopause

Ans : SQP 2020
(a) It is the onset of (a) It is the complete
Normal conception is not possible in some women. menstruation in a stoppage of
In such cases, ovum is taken and fertilized by the female. menstruation.
sperm in a test tube and when it reaches 32 cell (b) It occurs around (b) It occurs around
stage, it is implanted inside the uterus of the the age of 13 years. age of 55 years.
mother for future development of the child.
CH 11 : THE REPRODUCTIVE SYSTEM

5 – Ovary; 324. The figure shows the male urinogenital system in

6 – Uterus; mammals. Observe the diagram and answer the
7 – Urinary bladder; following:
8 – Urethra.
(ii) The wall of uterus thickens and is supplied
with blood capillaries.
(iii) The endometrium breaks down and causes
discharge of blood and mucus.

323. The diagram shown is the Lateral Section of a

testis of man.

(i) Label the parts 1-5.

(ii) Where are the seminiferous tubules located?
(iii) In which tissue does the sperm mature?
(iv) How does the sperm differ from a ovum?
Ans : SQP 2002

(i) 1 – Prostate gland;

2 – Cowper’s gland;
Study it carefully and answer the questions that 3 – Urethra;
follow: 4 – Sperm duct;
(i) Label the parts 1 to 4 of the diagram. 5 – Testis.
(ii) State the functions of the parts labelled 1 and (ii) Seminiferous tubules are located in the testis.
2. (iii) The sperm matures in epididymis.
(iii) Draw a labelled diagram of a sperm. (iv)
Ans : MAIN 2013 Sperm Ovum
(i) 1 – Vas deferens (a) It is the male (a) It is the female
2 – Seminiferous tubule gamete. gemate.
3 – Testicular lobules (b) It is motile. (b) It is non-motile
4 – Epididymis
(c) It has a tail. (c) Tail is absent.
(ii) Part 1 – To transport sperms.
Part 2 – Production of sperms.
325. The figure given below represents the female
(iii) reproductive system of a mammal:
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 373

(i) The foetus gets its nourishment from the to fertilise in a test tube and allowed to develop
mother’s blood through the placenta. up to a certain stage. Afterwards, the zygote is
(ii) Uterus. placed back in the uterus for further growth. In
(iii) The process by which the ovum is released this way, test tube babies are formed.
from the ovary.
299. Given below are name of certain hormones secreted
296. The diagram given below shows the male by various parts of a mammalian reproductive
urinogenital system of a human being. Study the system. Write down the site of their secretion.
diagram and answer the questions that follow (a) Testosterone (b) Progesterone
(c) Relaxin (d) Oestrogen
Ans : MAIN 2009

(a) Testosterone – Secreted by interstitial cells of

testis.
(b) Progesterone – Secreted by corpus luteum in
the ovary.
(c) Relaxin – Secreted by placenta.
(d) Oestrogen – Secreted by follicular cells of
ovarian follicle.

300. Difference between Sperm and Ovum.

Ans : SQP 2021
(i) Label the parts numbered 1 to 8.
(ii) Name the corresponding structure of part (4) Sperm Ovum
in female reproductive system. (a) It is the male (a) It is the female
(iii) What is the role of part 7? gamete. gamete.
Ans : SQP 2015
(b) It is produced in (b) It is produced in
(i) 1 – Urinary bladder the testis. the ovary.
2 – Ureter (c) It is elongated and (c) It is round and
3 – Cowper’s gland/bulbourethral gland contains head, tail has three outer
4 – Vas deferens and middle piece. layers.
5 – Urethra
6 – Testis
7 – Scrotum
8 – Epididymis
(ii) Oviduct FIVE MARKS QUESTIONS
(iii) Supports testes and maintains 2°C–3°C lower
than the body temperature for the production
301. The diagram below represents two reproductive
of sperms.
cells A and B. Study the same and then answer
297. What is placenta? State its functions. the questions that follow :
Ans : MAIN 2001

It is a disc-shaped structure attached to the utrine

wall. It is semi-permeable. Its functions are:
(a) To provide nutrients to the foetus.
(b) To transport O2 to the foetus.
(c) To remove urea from the foetus.

298. How are test tube babies formed?

Ans : SQP 2003

If the mother is incapable of conceiving, the (i) Identify the reproductive cells A and B.
mature egg is taken from the ovary and made (ii) Name the specific part of the reproductive
CH 11 : THE REPRODUCTIVE SYSTEM

267. Testis is located in the scrotum. (i) Name the process for the release of the part
labelled 1.
Ans : SQP 2015
(ii) Write the name of the structure marked 2.
Scrotum protects the testis. It also regulates
the temperature of the testis. Sperms need a Ans : MAIN 2024

temperature less than the body temperature for (i) Ovulation is the process whereby a mature
their production and development. ovarian follicle releases an egg (ovum) into
the fallopian tube.
268. Human testis is known as extra abdominal. (ii) The structure marked as 2 is corpus luteum.
Ans : COMP 2020 It develops from the remnants of the ovarian
follicle that has released its egg during
Testis are located in a scrotal sacs outside the
ovulation.
abdominal cavity. So, testis are called extra
abdominal. 272. “When an ovum gets fertilized, menstrual cycle
stops temporarily in a woman”. Give scientific
reason.
TWO MARKS QUESTIONS Ans : MAIN 2016

When fertilization takes place, the corpus luteum

is maintained which secretes large amounts of
269. Mention the surgical methods of contraception in:
progesterone hormone. This hormone maintains
(a) Men
the endometrium of the uterus and prevents its
(b) Women
rupturing. Hence, no menstruation takes place.
Ans : SQP 2025
273. Draw a diagram of human sperm and label the
(a) Vasectomy following parts: head, middle piece, acrosome,
(b) Tubectomy mitochondria, tail.
270. Draw a neat, labelled diagram of a human sperm. Ans : SQP 1996

Ans : SQP 2025

Diagram of human sperm.

274. Explain briefly :

Most often only one embryo is formed at a time
although there are two ovaries in women.
271. The diagram given below shows a section of the Ans : MAIN 1996
human ovary.
Normally only one egg matures in each ovary
every alternate month. This is the reason that
most often only one embryo is formed at a time
although there are two ovaries in women.

275. The statement given below is incorrect. Rewrite

the correct statement by changing the underlined
words of the statement.
The Graafian follicle, after ovulation turns into a
hormone producing tissue called Corpus callosum.
Ans : COMP 2017
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 375
Ans : SQ{ 2005
(ii) (1) Placenta – Exchange of gases and digested
(i) It is a vetical section of a testis. food.
(ii) 1. Sperm duct (Vas deferens). (2) Amniotic fluid – Protects foetus from
2. Epidermis. jerks/ shocks.
3. Tunica albuginea (iii) X– is fallopian tube (marked in diagram).
4. Vasa Efferentia or Collecting ducts. (iv) Identical twins – Develop from single egg
5. Seminiferous tubules after fertilization.
(iii) No 2. (Epididymis) – It is a tube-like structure Fraternal twins – from two separate eggs.
which is firmly attached to the testis. The
seminiferous tubules open into it through 306. Given below is the outline of the cross-section of
ducts. Epididymis is the chief store place of the male reproductive system.
spermatozoa.
No 5. (Seminiferous tubules) – They are
coiled structures and are involved in the
formation of spermatozoa. The seminiferous
tubules form a network at the anterior end of
the testis.

305. Given below is a diagrammatic representation of

the female reproductive system :

(i) Copy the outline onto your answer-sheet in

pencil and label the following parts-testis,
epidermis, seminal vesicles, vas deferens.
(ii) Name the hormone produced by the testis.
(iii) Why are sperms produced in large numbers ?
(iv) State the function of the seminal vesicles.
Ans : MAIN 2003

(i)
(i) Redraw the same on your answer-sheet and
then fill in and label the following parts :
(1) Right ovary (2) Uterus (3) Placenta
(4) Embryo (5) Amnion (6) Oviducal funnel.
(ii) State the function of the :
(1) Placenta
(2) Amniotic fluid.
(iii) Using the symbol ‘X’ indicates the region in
the diagram where fertilization occurs.
(iv) Differentiate between identical twins and
fraternal twins.
Ans : COMP 2004

(i) (ii) Testosterone.

(iii) Low count of sperms causes infertility because
large number of sperms go astray.
(iv) Seminal vesicles produce a secretion which
serves as a medium for the movement of
sperms towards the female oviduct.

307. Given below is the outline of the male reproductive

system :
CH 11 : THE REPRODUCTIVE SYSTEM

(ii) Where does fertilisation normally take (ii) Name the organ of the female body in which
place ? What is ‘Implantation’ that follows the foetus develops.
fertilisation? (iii) Name the part homologous to penis of male.
(iii) Mention the chromosome number of the egg (iv) What is ovulation ?
and zygote in humans. (v) Which two hormones are secreted by ovary ?
(iv) Explain the term ‘Gestation’. How long does
Ans : COMP 2017
Gestation last in humans ?
(v) Draw a neat, labelled diagram of a mature (i) Graafian follicle
human sperm. (ii) Uterus
(iii) Clitoris
Ans : SQP 2018
(iv) The process by which the matured ovum
(i) DCBA [It can also be CBAD as there is not a discharges from the ovary.
clear difference between egg cell and zygote] (v) Oestrogen and progesterone.
(ii) In the fallopian tube (Oviduct). Attachment
of blastocyst/embryo/fertilized ovum in the 314. The diagram shown below is the longitudinal
uterine wall (endometrium) of mother. section of a testis of man. Study it carefully and
(iii) Egg – 23 answer the question that follow :
Zygote – 46
(iv) Duration of embryonic development in the
uterus starting from implantation upto the
birth of a child. Gestation lasts in human for
280 days.
(v)

(i) Label the parts numbered 1 to 3 in the

diagram.
(ii) In which part of the testis are the sperms
produced?
(iii) State the functions of the parts labelled 1 and
3 in the diagram.
(iv) Name the cells that secrete Testosterone.
(v) Draw a neat, labelled diagram of a sperm.
313. The diagram given here represents the organs of Ans : MAIN 2019
female reproductive system:
(i) 1. Scrotum
2. Sperm duct/vasa deferens
3. Epididymis
(ii) Seminiferous tubules.
(iii) Scrotum : Brings the temperature 2 - 3 °C for
the maturation of sperms.
Epididymis : Store the sperms and help in
their maturity.
(iv) Leydig’s cells.
(v)
(i) Name the fully developed part of ovary
containing the ovum.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 377

(E) Scrotum
(ii) Vasectomy
(iii) Sperm duct/Vas deferens
(iv) Tubectomy
(v) Oviducts are ligated so that the egg may not
meet with the sperms.

310. Given below is a diagram of the lateral section of

a testis of a man. Study the same and answer the
questions that follow :

(i) Label the parts numbered 1 to 3 in the

diagram.
(ii) Mention any two functions of the part labelled
2 in the diagram.
(iii) Explain the significance of the part numbered
3 in the diagram.
(iv) Define the term ‘Gestation’. What is the
normal gestational period of the developing
human embryo?
(i) Label the parts numbered 1 to 4 of the (v) Mention the sex chromosomes in a male and
diagram. female embryo.
(ii) State the function of the parts labelled 1 and Ans : MAIN 2016
3.
(iii) What is the significance of the testes (i) 1-Umbilical cord, 2-Placenta, 3-Amniotic
being located in the scrotal sac outside the cavity full of amniotic fluid.
abdomen? (ii) Nutrition, Respiration, Excretion etc.
(iv) What is the role played by the inguinal canal? (iii) Amniotic fluid prevents desiccation of the
(v) What is semen ? foetus. It also prevents the foetus from jerks.
(iv) Pregnancy or gestation is the process or
Ans : MAIN 2013 period of development inside the womb of the
(i) 1 - Seminiferous tubule mother between conception and parturition
2 - Lobule in viviparous mammals including humans.
3 - Epididymis Gestation period is + 270 days or about 9
4 -Sperm duct (Vas deferens) months.
(ii) 1 - Produces sperm by the process called (v) Sex chromosome in male embryo is XY
spermatogenesis. whereas in female it is XX.
2 - Store sperms to make them mature and
312. Given below are diagrams showing the different
mobile.
stages in the process of fertilisation of an egg in
(iii) Since maturation of sperm takes place 2°
the human female reproductive tract.
to 3° lower than the body temperature
Study the diagrams and answer the questions
hence located in the scrotal sac outside the
abdomen.
(iv) It allows the descent of testes into the
scrotum.
(v) Semen is a milky fluid which is the mixture of
sperms and secretion from seminal, prostate
and Cowper’s gland.
(i) Arrange the letters given below each diagram
311. The diagram given below is that of a developing
in a logical sequence to show the correct order
human foetus. Study the diagram and then answer
in the process of fertilisation.
the questions that follow :
CH 11 : THE REPRODUCTIVE SYSTEM

289. Embryo and Foetus. 293. Sexual and Asexual reproduction.

Ans : MAIN 2001 Ans : SQP 2009

Embryo Foetus Sexual Asexual

(a) It is the (a) After two months Reproduction Reproduction
early stage of of gestation period, (a) It involves the (a) No gamete
development. the embryo is gametes. formation.
called foetus.
(b) Two individuals (b) One individual
(b) Features are (b) It has recognisable are needed. involves in
not developed appearance of main this type of
properly. features of a fully reproduction.
developed human.
294. State the difference between identical and
290. Identical and Fraternal twins. fraternal twins.
Ans : MAIN 2017 Ans : COMP 2022

Identical twins are formed by splitting of a

Identical Twins Fraternal Twins
fertilized egg and that separates into two equal
(a) They are (a) They are parts. They may be both boys or both girls (same
produced from produced from sex). They share a common placentas.
one egg. two eggs. Fraternal twins are formed by two eggs fertilized
(b) They are both (b) They may be by two sperms at a time. They may be both boys,
boys or both both boys or both girls or one boy or a girl. They have two
girls. both girls or one separate placentas.
boy and one girl.

291. Ureter and Urethra in man.

Ans : COMP 2005
THREE MARKS QUESTIONS

Ureter in man Urethra in man 295. The figure below represents the female
(a) It connects the (a) Common duct reproductive organs of the humans :
kidney and for the passage of
urinary bladder. urine and semen.
(b) It carries urine (b) It carries urine as
to the bladder. well as semen to
the exterior of the
body.

292. Sperm and Semen.

Ans : MAIN 2023

Sperm Semen
(a) It is the male (a) It is milky alkaline
gamete. fluid produced (i) How does the human embryo developing in
by the male re- the uterus obtain its nourishment ?
productive system. (ii) Which structure protects and nourishes the
(b) It is produced (b) It is produced developing embryo ?
by the testis. by the accessory (iii) Define ovulation.
glands. Ans : MAIN 1995
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 379

316. The figure given below is a technique.

(i) Name the process.

(ii) Name the fluid being taken out through the
syringe.
(iii) How is this process helpful ?
(iv) How is it misused ?
315. The diagram given below is that of a developing
(v) Label the parts 1 to 4.
human foetus in the womb. Study the same and
then answer the questions that follow : Ans : COMP 2012

(i) Amniocentesis
(ii) Amniotic fluid
(iii) Helpful in prenatal diagnosis of sex of the
foetus.
(iv) It is misused by people knowing about the sex
and if it is a female, they get it aborted since
their desire is for a male child.
(v) 1. Placenta
2. Amniotic cavity
3. Foetal cells
4. Uterine wall.

317. Study the diagram given below and then answer

(i) Name the part labelled 1. the following questions :
(ii) Mention any two functions of the part labelled (i) Label the parts 1 and 2
2. (ii) State any one function of the amniotic fluid.
(iii) Explain the role played by the part labelled 3. (iii) What is the role of the umbilical cord in the
(iv) What is the normal gestation period (in days) development of the foetus ?
of the developing embryo ?
Ans : COMP 2009

(i) The part labelled ‘1’ is Umbilical cord.

(ii) Two functions of the part labelled ‘2’
(placenta) are :
(1) Allows diffusion of substances from
mother to foetus and vice versa.
(2) Act as an endocrine gland by producing
estrogen and progesterone.
(iii) The role played by part labelled ‘3’ (Amniotic
fluid) is to protect the embryo from physical
damage by jerks or any kind of mechanical
shocks and prevents sticking of foetus to the
amnion.
(iv) The normal gestation period (in days) of the (iv) Name the part in the diagram which is
developing foetus is 280 days. endocrine in nature.
CH 11 : THE REPRODUCTIVE SYSTEM

(i) Name the parts labelled 1 to 5. (i) Name the parts ‘1’ to ‘5’ indicated by guidelines.
(ii) State the functions of the parts labelled 1 and (ii) What term is given to the period of
4. development of the foetus in the womb ?
(iii) Name the cells of part 5 that produce (iii) How many days does the foetus take to be
testosterone. fully developed ?
(iv) Why is the structure 5 persent outside the (iv) Mention two functions of the parts labelled
body in the scrotal sacs ? ‘2’ other than its endocrine function.
(v) What is semen ? (v) Name the hormone (any one) produced by
the part labelled ‘2’.
(vi) Name the function of part labelled ‘3’.
Ans : SQP 2002

(i) (1) Umbilical cord,

(2) Placenta,
(3) Amniotic fluid,
(4) Cervix,
(5) Uterine wall.
(ii) Gestation.
(iii) 280 days.
(iv) Provides diffusion of respiratory gases between
Ans : COMP 2010 mother and foetus, removes urea produced by
(i) (1) Seminal vesicle (2) Prostrate gland (3) foetus.
Urethra (4) Sperm duct (vas deferens) (5) (v) Progesterone
Testis (vi) Absorbs shocks.
(ii) Function : Part-1 : It produces a secretion
309. The diagram below represents a surgical
which serves as a medium for transportation
sterilization method in males. Study the same and
of the sperms. The mixture of this fluid and
answer the questions that follow :
sperms, produce a milky fluid called semen.
Part-4 : It helps in the transport of mature
sperms.
(iii) Leydig’s cells or interstitial cell.
(iv) It helps in temperature regulation in the
testes 2 – 3°C lower than that of body.
The regulation is brought by loosening or
contraction of the skin of scrotum wall.
(v) It is a milky fluid produced by the mixing of
sperms and secretion of seminal vesicles.

308. The diagram given below is that of a developing

human foetus in the womb. Study the same and
(i) Name the parts marked A, B, C, D and E.
then answer the questions that follow :
(ii) Give the name of the surgical method
represented in the diagram.
(iii) Which part is ligated or cut ?
(iv) Name the corresponding surgical method
conducted in females.
(v) Name the part which is ligated in females and
why?
Ans : MAIN 2009

(i) (A) Seminal vesicle

(B) Sperm duct/vas deferens
(C) Urethra
(D) Seminiferous tubule of testis
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 381

320. Given diagram is the outline of the cross section

of the male reproductive system:
(i) Copy the outline on to your answer sheet in
pencil and label the following parts – testis,
epididymis, seminal vesicles, vas deferens.

Ans : MAIN 2021

(i) 1 – Acrosome;
2 – Nucleus containing chromosomal material;
3 – Mitochondria;
4 – Tail
(ii) 23 chromosomes are present in sperms.
(ii) Name the hormone produced by the testis. (iii) Part 1 - Acrosome – To secrete an enzyme,
(iii) Why are sperms produced in large numbers? which helps the sperm to penetrate into the
(iv) State the function of the seminal vesicles. egg.
Ans : COMP 2023 Part 3 - Mitochondria – It produces energy
for the mobility of the sperm.
(i)
Part 4 - Tail – By the lashing movement of it,
the sperm can move forward.
(iv) Sperms are produced by the germinal
epithelium of seminiferous tubules of the testis.

322. The diagram given below represents the ventral

view of the female reproductive system:

(ii) Testosterone
(iii) The ovum in mammals does not exert any
chemical attraction on the sperms, hence
to ensure the fertilisation of the ovum it is
essential that large number of sperms are
produced.
(iv) Seminal vesicle produces secretion which
(i) Label the parts indicated by guidelines 1-8.
serves as a medium for transportation of
(ii) What happens to the uterus if fertilisation
sperms, activates the sperms, neutralises
takes place?
acidic environment of the urethra.
(iii) What happens to the uterus if fertilisation
321. The diagram refers to the structure of human has failed to take place?
sperm: Ans : SQP 2004
(i) Label the part 1-4.
(ii) What are the number of chromosomes present (i) 1 – Oviduct;
in the nucleus of the sperm? 2 – Funnel of oviduct;
(iii) State the functions of part 1,3 and 4. 3 – Ureter;
(iv) Where is sperm produced in man? 4 – Vagina;
CH 11 : THE REPRODUCTIVE SYSTEM
Ans : SQP 2007
319. Given below is a diagrammatic representation
(i) 1. Placenta of the ventral cross-sectional view of the female
2. Chorion reproductive system:
(ii) Amniotic fluid acts as a shock absorber and (i) Redraw the same on your answer sheet and
thus gives protection to the foetus. label the following parts:
(iii) Umbilical cord contains umbilical artery and
umbilical vein which acts as a string that
connects foetus with the placenta and thus
provides nourishment and takes away wastes
from the foetus.
(iv) Placenta.

318. Given below are diagrams showing different

stages in the process of fertilisation of an egg in
the female reproductive tract:

(1) Right ovary (2) Uterus

(3) Placenta (4) Embryo
(5) Amnion (6) Oviducal funnel.
(ii) State the function of the following:
(1) Placenta; (2) Amniotic fluid.
(i) Use the alphabet given below each diagram (iii) Using the symbol ‘X’ indicate the region in
to show the correct order in the process of the diagram where fertilisation occurs.
fertilisation. (iv) Differentiate between identical twins and
(ii) Where in the female reproductive system fraternal twins.
does this process normally take place?
Ans : SQP 2000
(iii) What is the biological term for the product of
fusion? (i)
(iv) What is the chromosome number of (1) the
egg (2) the fused product?
(v) Draw a neat labelled diagram of a mature
human sperm.
Ans : MAIN 2007

(i) D $ B $ C $ A.
(ii) Fallopian tube/Oviduct.
(iii) Zygote
(iv) (1) 23, (2) 23 pairs.
(v)

(ii) 1 – Placenta: Diffusion of respiratory gases,

digested food and excretory material between
mother and foetus.
2 – Amniotic fluid: Protects the foetus from
shocks and mechanical jerks.
(iii) X – marked is oviduct/fallopian tube.
(iv) Identical twins form by splitting of a fertilised
egg equally into two and have a common
placenta.
Fraternal twins form from two separate
fertilised eggs and have placenta of their own.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 383

Parts indicated by guidelines A to D are as follows: amniotic fluid present in between the amnion
A - Uterus, B - Fallopian tube, C - Ovary, D - and the embryo acts as a shock absorber.
Vagina
Give appropriate terms for each of the following: 327. The figure below represents the male reproductive
(i) The onset of reproductive phase in a young system of a human being:
female.
(ii) Rupture of follicle and release of ovum from
the ovary.
(iii) Monthly discharge of blood and disintegrated
tissues in human female.
(iv) Process of fusion of ovum and sperm.
(v) Fixing of developing zygote on the utrine
walls.
(vi) Which part of female reproductive system
receive semen?
Ans : MAIN 2015

(i) Menarche (i) Label parts 1-10.

(ii) Ovulation (ii) State one function each of the following:
(iii) Menstruation 1 - Testis; 2 - Penis; 3 - Scrotal sac; 4 -
(iv) Fertilisation Prostate gland; 5 - Seminal vesicle.
(v) Implantation
Ans : COMP 2012
(vi) Vagina
(i) 1. Ureter;
326. Given figure shows a foetus in a uterus: 2. Prostate gland;
(i) Label the parts 1-4 on the diagram. 3. Seminal vesicle;
(ii) Why is amniocentesis test done? 4. Vas deferens;
(iii) Briefly explain how a mammalian embryo is 5. Epididymis;
protected, nourished and how it respires. 6. Testis;
7. Penis;
8. Urethra;
9. Cowper’s gland;
10. Pubis.
(ii) 1. Testis – Production of sperms.
2. Penis – Deposition of semen into the
female’s vagina.
3. Scrotal sacs – To keep the temperature less
than body temperature for production of
sperms/ protection of testis.
4. Prostate gland – To secrete an alkaline
fluid into the semen.
5. Seminal vesicle – To secrete a white fluid
for the transportation of sperms.

Ans : SQP 2007

328. Complete the following statements :
(i) The cell formed through fertilization is called
(i) 1 – Umibilical cord; 2 – Placenta; 3 – Amniotic (gamete, sperm cell, zygote, ovum).
fluid; 4 – Uterus wall (ii) Which of the following organs develop first ?
(ii) It is a technique to find out whether there is (liver, heart, kidneys, notochord).
any kind of foetal abnormalities. (iii) How old is the embryo when it becomes a
(iii) An embryo gets its nutrients from the foetus ? (2 weeks, 2 months, 5 months, 28
mother’s blood through the placenta. Also days).
it gets O2 from the mother’s blood. It is (iv) The mammalian ovum was discovered by
protected by placenta and amnion. The (Hertwig, Von Baer, Schwann, Satoh).
CH 11 : THE REPRODUCTIVE SYSTEM

(v) The acrosome of sperm contains (hydrolytic

enzymes, mitochondria, DNA, RNA).
Ans : SQP 2004

(i) Zygote
(ii) Notochord
(iii) 2 months
(iv) Von Baer
(v) Hydrolytic enzyme

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ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 385

CHAPTER 12
HUMAN POPULATION

5. Economic reasons
SUMMARY 6. Desire for a male child
7. Lack of recreation
1. POPULATION 8. Better health care
Group of organisms of the same species living 9. Large scale immunization
in a geographically localized area and capable 10. Minimized food shortage
of interbreeding among themselves is termed as
1.3 Higher Population Density – Consequences
population. Literary, a population is a group
of organisms of the same species occupying Problems due to increased population density are:
a particular space at a particular time. The 1. Per capita income falls
population has a definite organization and 2. Decrease of natural resources
structure and exhibits various characteristics. 3. Health goes down
Population throughout the world and in India Overall large population of a country is the result
has been rising at an alarming rate. Problem of of having large families and the quality of life goes
rapidly growing population is the most serious and down.
increasing challenge that mankind is facing today.
The study of change in size and distribution of 1.4 Disadvantages of a Large Family
human population due to major fluctuations in Disadvantage of large family is as follows :
environment is called population dynamics. The
1. Insufficient education
physiological capacity of individual to produce
2. Insufficient medical care
offspring's is called biotic potential.
3. Malnutrition
1.1 Reasons for Rise in Human Population 4. Poor housing
Increased agricultural production and better 5. Poor health of mothers
public health and medical attention have increased 6. Economic pressure
the life expectancy. The sharply falling death 7. Poor clothing
rate is due to our success mainly on health front, 8. Children neglected socially
supplemented by spread of education. These led
to a tremendous increase in human population, 2. POPULATION CONTROL
reaching to an unmanageable extent. Population explosion is a severe threat to the
country. The control of population can be achieved
1.2 Population Explosion
by reducing the birth rate. In order to reduce the
Sharp, prolific increase in population of human birth rate people should be properly educated and
beings is called population explosion. should know about methods of family planning.
Factors responsible for population explosion in The ideal method of contraception (birth control)
India : does not exist. For most people there is some
Factors responsible for population explosion in inconvenience involved. Couples should consider
India are as follows : the full range, as different methods are suitable
1. Illiteracy for different phases of a man or woman’s fertile
2. Mortality rate life. Certain methods of contraception are suitable
3. Traditional beliefs only for females after child birth.
4. Religious and social customs
CH 12 : HUMAN POPULATION

2.1 Natural Family Planning 3. EVOLUTION

By recognizing the rhythm of their menstrual Evolution is the gradual change in the heritable
cycles, women can calculate the time when the egg characteristics of organisms from a simple to a
is produced by the ovary and can be fertilized by more complex form. Natural selection is the
man’s sperm. During this unsafe time (about 10 principle by which each trait, if useful is preserved
days in each month) the couple needs to abstain by natural.
from sex. There are three ways of estimating
the safe period calendar method, temperature
method and mucus method.

2.2 Artificial Family Planning

MULTIPLE CHOICE QUESTION
In recent times natural methods of contraception
are replaced by this method since all the natural 1. Assertion (A) : All food chains begin with
methods were unreliable. Artificial methods are : herbivores.
1. Barrier contraception : Condom for males, Reason (R) : Green plants are heterotrophs.
diaphragm and spermicidal agents for females. (a) Assertion is True and Reason is False
2. Intrauterine devices (IUDs) : Done in females. (b) Assertion is False and Reason is True
3. Pills and injections : Combined and mini pills (c) Both Assertion and Reason are True
are taken orally by females. Progesterone (d) Both Assertion and Reason are False
injections are useful for females. Ans : SQP 2025
4. Sterilization : Vasectomy is done in males
while tubectomy is done in females. Thus (d) is correct option.
5. Medical termination of pregnancy : If a 2. Birth rate is the number of live births per
woman has somehow become pregnant and a thousand persons in:
couple does not want to have the child then (a) 1 year (b) 2 years
the foetus can be removed by abortion. Three (c) 10 years (d) 20 years
months pregnancy can be aborted by this
method. Ans : MAIN 2024

The birth rate represents the number of live births

per thousand individuals in a population over a
specific period, usually one year.
Thus (a) is correct option.

3. Surgical method of sterilization in a woman

involves cutting and tying of :
(a) Ureter (b) Uterus
(b) Urethra (d) Oviduct
Ans : MAIN 2017

The surgical method of sterilization in women,

called tubectomy, involves cutting and tying
the oviducts (fallopian tubes). This blocks the
passage of eggs, preventing fertilization and thus
pregnancy.
Thus (d) is correct option.

4. Most of the cave paintings discovered are

associated with
(a) Homo erectus
(b) Cro-Magnon man
(c) Neanderthal man
(d) Dryopithecus
Ans : SQP 2010
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 387

Most cave paintings are linked to Cro-Magnon 8. The name Homo Sapiens can be assigned to
man, early modern humans known for creating (a) Cro-Magnon man
detailed art depicting animals and hunting scenes, (b) Peking man
such as those found in Lascaux and Altamira (c) Shivalik man
caves. (d) Java man
Thus (b) is correct option.
Ans : SQP 2015

5. Death rate is the number of death Cro-Magnon man is an early modern human and
(a) Per hundred people per year is classified under Homo sapiens. They lived in
(b) Per hundred people per decade Europe around 40,000 to 10,000 years ago and
(c) Per thousand people per decade had a physical appearance similar to modern
(d) Per thousand people per year humans. The other options, such as Peking man
Ans : SQP 2011
(Homo erectus), Shivalik man, and Java man
(Homo erectus), are earlier human ancestors, not
The death rate measures the number of deaths classified as Homo sapiens.
per thousand people per year. This standard unit Thus (a) is correct option.
helps compare mortality rates across populations.
It is commonly used to assess public health and 9. The false statement about Cro-Magnon man is
population trends. (a) He walked erect and was swift.
Thus (d) is correct option. (b) His cranial cavity was less than Homo sapiens.
(c) He was intelligent and cultured.
6. Population changes occur due to the movement (d) He started metal work, painting and farming.
of individuals. Emigration specifically involves
individuals leaving a population. Emigration Ans : MAIN 2021

refers to number of individuals This statement is false because Cro-Magnon man

(a) Moving into a population had a cranial capacity that was equal to or even
(b) Born in a population slightly larger than modern Homo sapiens. They
(c) Added to population growth were intelligent, walked erect, and are known for
(d) Moving out of population their cultural advancements, including art and
Ans : MAIN 2013
early forms of agriculture.
Thus (b) is correct option.
Emigration refers to the process where individuals
move out of a particular population to settle in a 10. Identify a non-renewable natural resource that is
different area. It is one of the factors that decrease overexploited due to increased population.
the size of a population. Conversely, immigration (a) Petroleum (b) Coal
is when individuals move into a population, (c) Both (a) and (b) (d) Wind
increasing its size.
Ans : SQP 2023
Thus (d) is correct option.
Both petroleum and coal are non-renewable
7. The human ancestor who has a cranial capacity natural resources that are heavily overexploited
of 850-1000 cc. due to the growing population and increased
(a) Homo Habilis (b) Cro-Magnon industrial activities. These fossil fuels are finite in
(c) Homo sapiens (d) Homo erectus supply and take millions of years to form, making
Ans : SQP 2015
their overuse a serious concern for future energy
sustainability.
Homo erectus is the human ancestor known to Thus (c) is correct option.
have a cranial capacity ranging between 850-1000
cc. This species is considered an important stage 11. When the environmental resistance is negligible
in human evolution, as it displayed significant and there is plenty of food and space, the
advancements in tool-making and perhaps early population would show
forms of social organization. Other species like (a) Zero growth curve
Homo habilis had a smaller cranial capacity (b) J-shaped growth curve
(around 500-800 cc), while Homo sapiens and (c) Sigmoid growth curve
Cro-Magnon had much larger cranial capacities (d) none of the above
Thus (d) is correct option.
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CH 12 : HUMAN POPULATION
Ans : COMP 2000
15. Darwin proposed the theory of origin of species
When environmental resistance is negligible and by
resources like food and space are abundant, a (a) Hybridisation
population grows rapidly without constraints, (b) Mutation
displaying a J-shaped growth curve. This (c) Natural selection
curve represents exponential growth, where (d) Acquired characters
the population size increases rapidly over time Ans : SQP 2012
without leveling off.
Thus (b) is correct option. Charles Darwin proposed the theory of the origin
of species by natural selection, which suggests that
12. Population of World in 2012 was approximately organisms better adapted to their environment
(a) 4 million tend to survive and reproduce, passing on
(b) 7 billion advantageous traits to the next generation. This
process gradually leads to the evolution of species
(c) 2 billion
over time.
(d) 10 million Thus (c) is correct option.
Ans : MAIN 2005
16. According to Lamarck, well-developed auricle
In 2012, the approximate population of the world muscles of rabbit have evolved due to
was around 7 billion. This milestone highlighted (a) Increasing need
significant global population growth due to (b) Internal vital force
advancements in medicine, agriculture, and (c) Continous use
reduced mortality rates. (d) All of these
Thus (b) is correct option.
Ans : COMP 2017
13. Birth rate is the number of lives birth According to Lamarck's theory of inheritance
(a) Per 100 people per decade of acquired characteristics, traits like the well-
(b) Per 1000 people per decade developed auricle muscles of rabbits evolved due
(c) Per 100 people per year to the increasing need for them, the influence of
(d) Per 1000 people per year an internal vital force, and their continuous use.
Ans : SQP 2007 Lamarck believed that organisms could develop
traits during their lifetime and pass them on to
The birth rate is defined as the number of
their offspring.
live births per 1000 people per year in a given
Thus (d) is correct option.
population. It is a key demographic indicator
used to measure population growth. 17. A contraceptive for men only
Thus (d) is correct option. (a) Condom
(b) Diaphragm
14. Australopithecus is also known as Southern ape,
(c) Copper-T
because it had
(d) Loop
(a) Ape-like characters
(b) Man-like characters Ans : COMP 2020

(c) Both (a) and (b) A condom is a contraceptive device designed

(d) Monkey-like characters specifically for men. It is a barrier method
used to prevent sperm from entering the female
Ans : COMP 2011 reproductive tract during sexual intercourse,
Australopithecus, known as the Southern helping to prevent pregnancy and reduce the risk
ape, had a mix of both ape-like and man-like of sexually transmitted infections (STIs). The
characters. While it had a small brain and some other options, such as diaphragm, copper-T, and
primitive features resembling apes, it also showed loop, are contraceptive devices for women.
bipedalism and certain anatomical adaptations Thus (a) is correct option.
similar to early humans, marking it as an
18. Marriageable age for girls is
important ancestor in human evolution.
(a) 18 (b) 21
Thus (c) is correct option.
(c) 20 (d) 13
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 389
Ans : MAIN 2001
Homo erectus lived around 2 million years ago
The legal marriageable age for girls in India (mya). This species is considered one of the
is 18 years. This law is designed to prevent earliest human ancestors that exhibited significant
child marriages and ensure that girls have advancements, including the use of tools and fire.
the opportunity to complete their education Homo sapiens, Cro-Magnon, and Neanderthals
and mature physically and emotionally before appeared much later in human evolution.
marriage. Thus (a) is correct option.
Thus (d) is correct option.
22. In the evolution of man, Homo erectus is
19. Human population growth curve resembles a considered to be evolved from
(a) S-shaped curve (a) Dryopithecus
(b) J-shaped curve (b) Ramapithecus
(c) Zigzag curve (c) Cro-Magnon
(d) None of the above
(d) Australopithecus
Ans : COMP 2005
Ans : MAIN 2017
The human population growth curve generally
In human evolution, Homo erectus is believed to have
resembles an S-shaped curve (also known as a
evolved from Australopithecus, which exhibited
sigmoid curve). Initially, the population grows
both ape-like and human-like characteristics,
slowly, followed by a period of rapid growth, and
including bipedalism. Australopithecus represents
eventually levels off as it approaches the carrying
an important transitional species leading to more
capacity of the environment due to limiting
advanced humans like Homo erectus, who had
factors like resources and space.
larger brain capacity and more refined tool usage.
Thus (b) is correct option.
Thus (d) is correct option.
20. Darwin in his ‘natural selection theory’ did not
23. What was directly responsible for the rapid rise of
believed in any role of which one of the following
world population in the twentieth century?
in organic evolution?
(a) Use of antibiotics and prophylactic
(a) Discontinuous variations
vaccinations
(b) Parasites and predators as natural enemies
(b) Increased food production
(c) Survival of the fittest
(c) Better transport facilities
(d) Struggle for existence
(d) Better education and job prospects
Ans : COMP 2010
Ans : MAIN 2016
In Darwin's theory of natural selection, he
The use of antibiotics and prophylactic
primarily focused on continuous variations as the
vaccinations in the 20th century significantly
basis for evolution, where small, gradual changes
reduced death rates by controlling infectious
accumulate over time. He did not give much
diseases, which was directly responsible for the
importance to discontinuous variations, which
rapid rise in the world population. This, along
are large, sudden changes (now associated with
with advancements in medical care, led to longer
mutations). Darwin emphasized factors like the
life expectancies and a population boom.
struggle for existence, survival of the fittest, and
Thus (a) is correct option.
the role of parasites and predators in shaping
natural selection. 24. The major advantage of bipedal locomotion is
Thus (a) is correct option. that it
(a) Increases speed
21. The species of human being who lived around 2
(b) Reduces body weight
mya.
(c) Provides better body support
(a) Homo sapiens (d) Releases the forelimbs for other better
(b) Cro-Magnon functions
(c) Neanderthals
Ans : COMP 2015
(d) Homo erectus
The major advantage of bipedal locomotion is that
Ans : SQP 2015
it releases the forelimbs, allowing them to be used
CH 12 : HUMAN POPULATION
Ans : COMP 2015
78. Tubectomy is the surgical method of sterilisation
Minerals and petroleum in males.

69. A surgical method of fertility control (sterilization) Ans : MAIN 2010

in males. False, Vasectomy is the surgical method of

sterilisation in males.
Ans : SQP 2016

Vasectomy
DIRECTION : Give appropriate biological or
70. A surgical method of fertility control (sterilization) technical term for the following :
in females.
Ans : COMP 2019
79. The difference between the birth rate and the
death rate.
Tubectomy
Ans : COMP 2018
71. The technical term used for the difference between Growth rate of population
the birth rate and the death rate in a population.
Ans : MAIN 2015
80. The method of contraception in which the sperm
duct is cut and ligated.
Growth rate
Ans : SQP 2014
72. The number of males and females in a population Vasectomy
Population and its Control
Ans : SQP 2016
DIRECTION : Give biological explanations for the
Sex ratio following :

73. The surgical method of fertility control in females. 81. Education is very important for population
Ans : COMP 2019 control.
Tubectomy Ans : MAIN 2018

74. The numerical difference between birth rate and Helps people know about family planning and
death rate. consequences of having large families.

Ans : MAIN 2000

DIRECTION : Explain the following term :
Growth rate

75. Give an example of IUD. 82. Natality

Ans : SQP 2005

Ans : SQP 2017

Copper-T It refers to the number of live births produced per

thousand people of the population per year. It is
76. A non-conventional source of energy. also called as birth rate.
Ans : COMP 2007 83. Population Density
Wind energy Ans : MAIN 2010

It is defined as the number of individuals of a

DIRECTION : Rewrite the wrong statement by species per unit area.
inserting a word/ words.

DIRECTION : Distinguish between:

77. Death rate is the number of deaths of a given
population per year.
84. Birth rate (natality) and death rate (mortality)
Ans : SQP 2004
Ans : SQP 2012
Death rate is the number of deaths per 1000
people of a given population per year.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 391
Ans : COMP 2014 Ans : SQP 2018

Mortality refers to the death rate in a population. Lamarck's theory of evolution is known as the
It measures the number of deaths per unit of theory of inheritance of acquired characters. He
population within a specific time period, often proposed that organisms could pass on traits they
used to assess the health and longevity of a acquired during their lifetime to their offspring,
population. which would lead to evolutionary changes over
Thus (d) is correct option. generations. This theory is distinct from Darwin’s
natural selection.
32. The first scientist who proposed his theory for the Thus (d) is correct option.
evolution was
(a) Darwin 35. Human population is estimated to be 7.2 billion
(b) Mendel by
(c) Wallace (a) 2000 (b) 2005
(d) Lamarck (c) 2015 (d) 2010
Ans : SQP 2011 Ans : COMP 2019

Jean-Baptiste Lamarck was the first scientist The human population was estimated to reach
to propose a theory of evolution. His theory, around 7.2 billion by the year 2015. This milestone
known as Lamarckism, suggested that organisms was achieved due to factors like improved
evolve through the inheritance of acquired healthcare, decreased mortality rates, and high
characteristics. Although later largely discredited, birth rates in many parts of the world.
Lamarck's ideas laid the groundwork for future Thus (c) is correct option.
evolutionary theories, including Darwin's theory
of natural selection. 36. In the study of human evolution, certain
Thus (d) is correct option. ancestors are known for specific traits or skills.
One ancestor, often called the "handy man," was
33. Darwin’s theory of evolution fails to explain the notable for using tools, marking a significant step
(a) Role of environment in human development. The human ancestor who
(b) Overproduction was called as handy man.
(c) Origin and transmission of variations (a) Neanderthals
(d) Survival of the fittest (b) Homo erectus
(c) Cro-Magnon
Ans : MAIN 2015
(d) Homo-Habilis
Darwin's theory of evolution explains natural
selection, survival of the fittest, and the influence Ans : SQP 2019

of the environment, but it does not explain Homo habilis is often referred to as the "handy
the origin and transmission of variations. The man" because it was one of the earliest human
mechanism behind genetic variations was not ancestors known to use tools. The discovery of
understood until the discovery of genetics by simple stone tools alongside Homo habilis fossils
Mendel, which provided insights into how traits indicates their ability to create and use tools,
are inherited. marking an important step in human evolution.
Thus (c) is correct option. Thus (b) is correct option.

37. Population explosion often results from a high

DIRECTION : Case Based Questions birth rate surpassing death rates, causing rapid
growth. Identifying the main cause helps in
34. Lamarck’s theory suggests that organisms can
understanding population trends.Identify the
pass traits acquired during their lifetime to their
major cause of population explosion from those
offspring, proposing a unique view on evolution
given below
compared to natural selection. Lamarck’s theory
(a) High natality rate
of evolution is also called as
(b) Literacy
(a) Theory of natural selection
(c) Low natality rate
(b) Survival of the fittest
(d) None of these
(c) Theory of special creation
(d) Inheritance of acquired characters Ans : SQP 2019
CH 12 : HUMAN POPULATION

A high natality rate (birth rate) is a major (a) Moth

cause of population explosion. When the birth (b) Butterfly
rate exceeds the death rate, it leads to rapid (c) Honey bee
population growth, especially when combined (d) Cockroach
with advancements in healthcare and lower infant
Ans : SQP 2019
mortality rates.
Thus (a) is correct option. The organism studied for industrial melanism
was the peppered moth. During the Industrial
38. In female sterilization, a surgical method is Revolution in England, darker-colored moths
used to prevent eggs from reaching the uterus, became more common due to pollution darkening
effectively providing permanent contraception. the trees, providing better camouflage against
This procedure involves cutting and tying a predators. This phenomenon was a key example
specific reproductive structure. Surgical method of natural selection in action.
of sterilisation in a woman involves cutting and Thus (a) is correct option.
tying of
(a) Ureter 41. Lamarckism, which suggests acquired traits are
inherited, struggles to explain certain natural
(b) Uterus
phenomena where traits aren't influenced by
(c) Oviduct acquired characteristics. Lamarckism fails to
(d) Urethra explain which of the following phenomenon?
Ans : SQP 2007
(a) An intellectual person having a dull son
(b) Absence of all the four limbs amongst
The surgical method of sterilization in women, amphibians
known as tubal ligation, involves the cutting (c) Exceptionally long neck of giraffe
and tying of the oviducts (fallopian tubes). This (d) Loss of vision in caved-welling mammals
prevents the egg from traveling from the ovaries
to the uterus and blocks sperm from reaching the Ans : MAIN 2009

egg, thereby preventing fertilization. Lamarckism suggests that acquired traits are
Thus (c) is correct option. passed to offspring, which would imply that
intellectual abilities (an acquired characteristic)
39. Copper-releasing IUDs prevent fertilization by should be inherited. However, intellectual ability
releasing ions that affect specific reproductive is not directly inherited, making this example
activities, aiding in contraception. Copper a limitation of Lamarck's theory, as it does not
releasing IUDs are used for suppressing the account for genetic inheritance independent of
(a) Activity of ova acquired traits.
(b) Motility of the sperms Thus (a) is correct option.
(c) Activity of the uterus
42. August Weissman experiment involved cutting
(d) Motility of ova tails of mice over generations, yet their offspring
Ans : SQP 2000 still had normal tails, disproving Lamarck’s theory
Copper-releasing IUDs (Intrauterine Devices) of acquired inheritance. Concept of inheritance
work primarily by releasing copper ions, which of acquired characters was disapproved by the
are toxic to sperm. This disrupts the motility of experiments of
the sperms, preventing them from fertilizing the (a) Weismann (b) Oparin
egg. Copper IUDs do not suppress the activity of (c) Fox (d) Darwin
ova or the uterus, but they create an environment Ans : COMP 2019
that is hostile to sperm. The concept of inheritance of acquired characters
Thus (b) is correct option. was disapproved by Weismann through
40. Industrial melanism, observed during the experiments on mice, where he cut off their tails
industrial revolution, involved a specific organism for several generations. The offspring still had
developing darker coloration to better camouflage tails, showing acquired traits aren't inherited.
in polluted environments. The organism studied This rejected Lamarck's theory and supported
for Industrial melanism was a genetic inheritance.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 393

Thus (a) is correct option. (a) P – Economic pressure, Q – Biotic potential.

(b) P – Decreased natural resources, Q – Poor
43. Scientists have studied various ancient species health care.
that could link humans and apes. Among (c) P – Malnutrition, Q – Economic prosperity.
them, one species is widely seen as the common (d) P – Per capita income rise, Q – Larger
ancestor, displaying traits found in both lineages families.
The common ancestor to both man and ape is
(a) Dryopithecus Ans : COMP 2010

(b) Australopithecus Population explosion leads to the depletion of

(c) Sinanthropus natural resources and strains the health care
(d) Homo erectus system, reducing its efficiency.
Ans : Thus (b) is the correct option.
Dryopithecus is considered the common ancestor 46. Priya attempted to match population control
of humans and apes. It lived around 9 to 12 million methods with their corresponding category. She
years ago and had both ape-like and human-like noted the following :
traits, making it a key species in the evolutionary
link between apes and humans. Method Category
Thus (a) is correct option. P Natural family planning based on
menstrual cycle..
DIRECTION : Matching Type Question Q Contraceptive pills taken by females.
Identify the correct pair of methods:
44. Priya studied the factors contributing to the rise
(a) P – Calendar method, Q – Sterilization.
in human population. She noted the following:
(b) P – Temperature method, Q – Progesterone
Factor Effect on population growth injections.
(c) P – IUDs, Q – Condoms.
P Reduced mortality and increased
(d) P – Medical termination, Q – Barrier method.
life expectancy.
Ans : SQP 2015
Q Desire for a male child leading to
more births. The temperature method is part of natural
family planning, while progesterone injections
Identify the correct pair of factors:
are a hormonal method of contraception used by
(a) P – Better health care, Q – Traditional beliefs.
females.
(b) P – Illiteracy, Q – Malnutrition.
Thus (a) is the correct option.
(c) P – Mortality rate, Q – Economic pressure.
(d) P – Population control, Q – Per capita in com 47. Ravi studied the disadvantages of a large family.
Ans : MAIN 2012 He noted the following :
Better health care reduces death rates and Disadvantage Impact on family members
increases life expectancy, contributing to
P Children may not receive
population growth. Traditional beliefs, including
adequate education..
a desire for a male child, can result in more births.
Thus (a) is the correct option. Q Economic resources are spread
too thin.
45. Ravi was asked to identify consequences of
Identify the correct pair of disadvantages:
population explosion. He listed the following:
(a) P – Poor health of mothers, Q – Economic
Consequence Impact on the population pressure.
(b) P – Poor housing, Q – Lack of recreation.
P Natural resources deplete
(c) P – Insufficient education, Q – Economic
rapidly.
pressure.
Q Health services become (d) P – Malnutrition, Q – Reduced natural
inadequate. resources.
Identify the correct pair of consequences: Ans : COMP 2010
CH 12 : HUMAN POPULATION

for functions such as tool use, carrying objects, on the evolutionary path leading to humans. It
and complex manipulation. This was a significant predates other ancestors like Australopithecus,
evolutionary step in human development, enabling Neanderthals, and Cro-Magnon, which appeared
greater dexterity and cognitive advancements. much later in the evolutionary time line and are
Thus (d) is correct option. closer to modern humans.
Thus (b) is correct option.
25. Robert Malthus in his Essay on Population stated
that 28. Vasectomy is cutting of
(a) Population grows at arithmetic rate and the (a) Vas deferens
food at the geometric rate (b) Fallopian tube
(b) Population grows at the same rate as the food (c) Seminal vesicle
(c) Population can grow indefinitely if enough (d) Seminiferous tubule
food is provided
Ans : MAIN 2010
(d) Population grows at geometric rate and the
food at the arithmetic rate Vasectomy is a surgical procedure for male
sterilization that involves cutting and sealing the
Ans : SQP 2010
vas deferens. This prevents sperm from mixing
Robert Malthus theorized that population growth with semen and being released during ejaculation,
could continue indefinitely as long as resources, effectively preventing fertilization.
especially food, were sufficient to support it. Thus (a) is correct option.
However, he warned that since resources like
food typically grow at a slower rate, unchecked 29. MTP is advised by the doctor upto the pregnancy
population growth could eventually lead to of
shortages, with natural limits curbing the (a) 15 weeks
population through famine, disease, or other (b) 12 weeks
factors. (c) 20 weeks
Thus (c) is correct option. (d) 22 weeks
Ans : COMP 2013
26. The theory of natural selection was proposed by
(a) Darwin Doctors generally advise Medical Termination of
(b) Lamarck Pregnancy (MTP) up to 12 weeks for routine cases
(c) Wallace due to lower medical risks. However, with special
(d) Mendel approval and under specific circumstances, MTP
can be performed up to 20 weeks, particularly when
Ans : COMP 2018
health risks to the mother or fetal abnormalities
The theory of natural selection was proposed are present.
by Charles Darwin. This theory suggests that Thus (b) is correct option.
individuals with advantageous traits are more
likely to survive and reproduce, passing those 30. Ideal contraceptive should not be
traits to future generations, leading to evolutionary (a) User-friendly (b) Effective
changes over time. Alfred Wallace independently (c) Easily available (d) Expensive
conceived a similar idea, but Darwin is most Ans : SQP 2011
credited with the development and publication of
An ideal contraceptive should be user-friendly,
the theory.
effective, and easily available to ensure it can be
Thus (a) is correct option.
widely and effectively used. Being expensive would
27. Identify the pre-human ancestor limit accessibility and reduce its practicality as an
(a) Australopithecus ideal contraceptive option.
(b) Ramapithecus Thus (d) is correct option.
(c) Neanderthal man
31. Mortality refers to the
(d) Cro-Magnon
(a) Birth rate
Ans : MAIN 2016 (b) Replacement rate
Ramapithecus is considered a pre-human ancestor (c) Fertility rate
and is one of the early primates thought to be (d) Death rate
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 395
Ans : COMP 2020
Demography.
Raj correctly mentions the temperature method,
while Sonu lists the calendar and mucus methods, 58. The number of individuals inhabiting per unit
which are all natural family planning methods. area.
Thus (d) is the correct option. Ans : SQP 2016

53. A teacher asked her students to identify two Population density

disadvantages of having a large family.
59. The popular sign for family planning in India.
Raj said: "Poor education and poor health."
Sonu said: "Economic pressure and malnutrition." Ans : MAIN 2019

Lata said: "Better housing and higher per capita Inverted red triangle
income."
Abhay said: "Social neglect of children and 60. The minimum marriage age for girls in India.
economic prosperity." Ans : COMP 2020
Who were correct?
(a) Raj and Sonu Eighteen years
(b) Sonu and Abhay
61. Sterilization technique in males involving cutting
(c) Lata and Abhay
and tying sperm duct.
(d) Raj and Lata
Ans : SQP 2021
Ans : SQP 2010
Vasectomy
Raj correctly mentions poor education and health,
while Sonu mentions economic pressure and 62. The scientific study of human population.
malnutrition, all disadvantages of large families.
Ans : MAIN 2023
Thus (a) is the correct option.
Demography

63. Changes that occur in a population due to

ONE MARK QUESTIONS alternation in growth rate, sex ratio, etc.
Ans : COMP 2000

Population dynamics
DIRECTION : Name the following :
64. The instrument used for cutting and tying the
oviduct in females.
54. The surgical method of sterilization in the human
female. Ans : MAIN 2001

Ans : COMP 2006 Laproscopy

Tubectomy 65. The chemicals which kills sperms.
55. A statistical study of human population of a Ans : SQP 2005

region. Spermicides.
Ans : SQP 2001, 2003
66. The statistical study of the human population of
Demography a region.
56. The number of persons per square kilometre at Ans : COMP 2007

any one given time. Demography

Ans : MAIN 1995
67. Two renewable resources for the mankind.
Population Density.
Ans : MAIN 2010

57. The statistical study of the human population of Forest and soil
a region.
68. Two non-renewable resources for the mankind.
Ans : COMP 2000
CH 12 : HUMAN POPULATION

In large families, children may not receive proper 50. A teacher asked her students to provide two
education due to financial constraints, and examples of factors leading to population
economic pressure makes it difficult to provide for explosion in India.
everyone adequately. Raj said: "Illiteracy and better health care."
Thus (c) is the correct option. Sonu said: "Increased mortality and improved
nutrition."
48. Priya tried to categorize family planning methods. Lata said: "Desire for a male child and economic
She listed the following: reasons."
Method Type Abhay said: "Large-scale immunization and
minimized food shortage."
P Children may not receive adequate Who were correct?
education.. (a) Raj and Lata
Q Economic resources are spread too (b) Sonu and Abhay
thin. (c) Lata and Abhay
(d) Raj and Sonu
Identify the correct pair of methods:
(a) P – Condoms, Q – Tubectomy. Ans : SQP 2019
(b) P – Diaphragm, Q – Vasectomy. Lata correctly lists desire for a male child and
(c) P – IUDs, Q – Calendar method. economic reasons, while Abhay lists immunization
(d) P – Injections, Q – Barrier method. and reduced food shortages, all contributing to
Ans : MAIN 2017 population growth in India.
Thus (c) is the correct option.
A diaphragm is a barrier method that prevents
sperm from entering the uterus, while vasectomy 51. A teacher asked her students to list two methods
is a surgical method that cuts or blocks the sperm of artificial family planning.
ducts to prevent sperm release. Raj said: "Condoms and calendar method."
Thus (b) is the correct option. Sonu said: "Pills and vasectomy."
Lata said: "Medical termination and temperature
DIRECTION : Conversation Type Question method."
Abhay said: "Diaphragm and IUDs."
49. A teacher asked her students to list two Who were correct?
consequences of population explosion. (a) Raj and Sonu.
Raj said: "Depletion of natural resources and (b) Sonu and Abhay.
lower health standards." (c) Lata and Abhay.
Sonu said: "Increased education and economic (d) Sonu and Lata.
prosperity." Ans : MAIN 2021
Lata said: "Per capita income decreases and
Sonu and Abhay both correctly listed artificial
health issues rise."
methods. Sonu mentioned pills and vasectomy,
Abhay said: "Increased food production and
and Abhay mentioned diaphragm and IUDs, all
better housing."
of which are valid artificial methods.
Who were correct?
Thus (b) is the correct option.
(a) Raj and Lata
(b) Sonu and Abhay 52. A teacher asked her students to name two natural
(c) Lata and Abhay family planning methods.
Raj said: "Temperature method and diaphragm."
(d) Raj and Sonu
Sonu said: "Calendar method and mucus method."
Ans : COMP 2018 Lata said: "Sterilization and calendar method."
Abhay said: "Vasectomy and mucus method."
Raj correctly mentions the depletion of resources
Who were correct?
and lower health standards, while Lata mentions
(a) Raj and Abhay.
the decrease in per capita income and health
(b) Sonu and Lata.
issues, both consequences of population explosion.
(c) Sonu and Abhay.
Thus (a) is the correct option.
(d) Raj and Sonu.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 397

Natality Mortality 91. Define Birth rate.

Ans : COMP 2003
(a) It is the number (a) It is the number
of live births per of deaths per It is defined as the number of births per thousand
1000 people of 1000 people of people of a given population per year.
the population the population
92. Define Death rate.
per year. per year.
Ans : SQP 1996

85. Demography and Population density [Definition] It is the number of deaths per 1000 of population
per year in a particular area.
Ans : MAIN 2017

Demography : Branch of science dealing with 93. What are the age restrictions for marriage for
statistical study per unit of human population boys and girls in India ?
area at a given time. Ans : MAIN 2009
Population density : Number of individuals of a
species The age restrictions for marriage for boys is 21
years and of girls is 18 years.

DIRECTION : Answer the following : 94. What is the sign of family welfare ?
Ans : COMP 2010
86. Mention two reasons for increase in population
in India. Inverted red triangle.

Ans : SQP 2004 95. What factors govern the growth of a population ?
(i) Illiteracy. Ans : SQP 2015
(ii) Economic reasons. Birth rate, death rate, emigration and immigration.
87. What are the age restrictions for marriage by law 96. What are spermicides ?
for boys and girls in India ?
Ans : MAIN 2017
Ans : MAIN 2003
These are certain chemical agents that kill the
21 years for boys and 18 years for girls. sperms.
88. Name two surgical techniques that can be used to 97. What is census ?
prevent pregnancy.
Ans : SQP 2019
Ans : COMP 2003
It is the counting of existing population at a fixed
Vasectomy for males and Tubectomy for females. time as regards name, age, sex, occupation, date
89. Give three advantages of a small family. of birth, matrimonial status, race, religion and
education.
Ans : MAIN 2010
98. What are the problems posed by increased
Advantage of small family :
population in India ?
(i) Adequate and balanced diet can be provided
to each member of the family. Ans : COMP 2022
(ii) Proper medical aids can be provided. Food shortage, housing problem, poor health and
(iii) Each member can be given education of poor standard of living.
higher standard.
99. What are the causes of increased population in
90. The birth rate in India is very high. India?
Ans : SQP 2019
Ans : SQP 2023
Due to better medical care there is a fall in death Early marriage, increase in birth rate, lack of
rate both for infants and the old. As long as birth knowledge about family planning, advancement
rate exceeds death rate population grows rapidly. in medical sciences and improved life expectancy.
CH 12 : HUMAN POPULATION

TWO MARKS QUESTIONS 166. Give biological reasons for the following statement
: Cutting of trees should be discouraged.
Ans : COMP 2017
161. "Birth rate in India is very high." Mention Two
reasons in support of the statement. Cutting of tree should be discouraged because
it would lead to less utilization of CO2 in
Ans : MAIN 2024 photosynthesis due to which rise in CO2 will
Illiteracy,children area gift of God, sign of lead to greater retention of solar radiation in the
prosperity, due to high infant mortality, more atmosphere causing global warming.
helping hands for family income, do not accept
family planning methods, desire for a male child, 167. Draw the female and male reproductive system
lack of recreation showing tubectomy and vasectomy.
Ans : SQP 2015
162. The need to limit the size of the family is more
vital today than ever before. Give two reasons.
Ans : COMP 1993,1992,1997

Due to growth in population every year, the

country has to spend more on food, clothing
and housing. A larger population produces
more wastes causing pollution and upsetting the
ecological balance.

163. Why resources cannot keep pace with the rising

population? Give two examples. 168. Define sustainable development.
Ans : SQP 1996 Ans : MAIN 2015
(i) Population grows by geometric progression Sustainable resources refers to using resources in
while food production increases by arithmetic such a way that it can be used in the future. It
progression. must be used to check the over exploitation of
(ii) Indiscriminate cutting of trees to make land resources. This means that development must be
available for cultivation is one of the serious done without disturbing the developments of the
consequences of overpopulation. future generation.

164. Write any two major reasons for the population 169. Vasectomy
explosion in the world. Ans : SQP 2018
Ans : MAIN 2012, 2013 Vasectomy: It is the cutting and ligating the vas
Better healthcare at all age group/Fewer deaths deferens in males.
due to better medical aids/Minimized food
shortage/Balanced and improved nutrition/Large 170. What are the advantages of IUD ?
scale immunization. Ans : COMP 2017

165. State two reasons for the increase of population (i) IUD is easy to use and very effective.
in India. (ii) IUD is very effective in birth control.
(iii) It is mainly suitable for those who want to
Ans : SQP 2015 practise small family norms after having one
The increase of population in India is due to the or two children.
following reasons :
Illiteracy/desire for a male child/children are gift 171. What are the disadvantages of IUD ?
of god/lack of recreation/poor family income/ Ans : MAIN 2019
universality of marriage/child marriages/lack of (i) IUD can be expelled from the body.
family planning/mortality rate among low income (ii) It requires replacement every year.
group. (iii) It may cause infection leading to sterility.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 399

DIRECTION : Choose the correct option from the Live births

brackets:
120. Pregnancy can be avoided by using ______.
112. Death rate is the number of death Ans : MAIN 2013
[Per hundred people per year, per thousand
Contraceptive pills
people per year, per hundred people per decade,
per thousand people per decade] 121. The addition of new individuals to the population
Ans : COMP 2011
from other localities is called______.

Per thousand people per year. Ans : MAIN 2013

Immigration
113. Vasectomy is cutting of
[Fallopian tube, vas deferens, seminal vesicle, 122. Family planning’s popular sign is ______
seminiferous tubule] triangle.
Ans : SQP 2013 Ans : COMP 2014

Vas deferens. Inverted red

114. Marriageable age for girls is 123. Population increases in ______ ratio while
[18, 21, 13, 20] food production increases in ______ ratio.
Ans : MAIN 2015 Ans : SQP 2013

18. Geometric; arithmetic

115. A contraceptive for men only 124. Non-conventional energy includes ______.
[Diaphragm, condom, copper-T, loop]
Ans : COMP 2019
Ans : SQP 2017
Tidal energy
Condom.
125. Population increases in geometric ratio while food
116. The statistical study of human population. increase in ______ratio.
[Demography, population density, population,
Ans : SQP 2011
growth rate]
Arithmetic
Ans : COMP 2018

Demography 126. ______ is misused for sex tests.

Ans : COMP 2015
117. The marriageable age for boys
[18, 21, 20, 25] Amniocentesis
Ans : SQP 2016 127. The addition of new individuals to the population
21 from other localities is called ______.
Ans : SQP 2019
118. Intra uterine devices prevent
[Fertilization, implantation, meeting of sperm and Immigration
ovum, release of ovum]
128. As per the UN report the world population will
Ans : MAIN 2000 reach ______ billion by the year 2020.
Implantation Ans : COMP 2020

7.5
DIRECTION : Complete the following:
129. ______ is the technical term used for the
119. Birth rate is the number of ______ births per difference between the birth rate and death rate.
thousand of the population per year. Ans : SQP 2021

Ans : SQP 2011 Growth rate

CH 12 : HUMAN POPULATION

100. State some of the common methods of birth (i) Human population growth curve resembles (J
control practiced in India. shaped curve, zig zag curve, parabola curve,
S shaped curve).
Ans : MAIN 2011
(ii) The carrying capacity of a population is
Oral pills, condoms, ND, Diaphragm, Spermicides, determined by its (limiting sources, natality,
rhythm method. mortality, population growth curve).
(iii) Which of the following means of birth control
101. When is the world population day celebrated? is most effective in preventing AIDS ?
Ans : SQP 2015 (Condom, Pill, diaphragm, spermicidal jelly).
(iv) The rate at which a population grows or
World population day is celebrated on 11th July. declines depend upon the rate of (births,
102. What is the sign of family welfare in our country? immigration, deaths, all of these).
(v) Minimum age of marriage for boys is 21 years
Ans : COMP 2017 and for girls is (17, 18, 19, 20) years.
The sign of family welfare in our country is an Ans : MAIN 2019
‘Inverted Red Triangle’. (i) J shaped curve
(ii) Limiting resources
103. What is population explosion?
(iii) Condom
Ans : SQP 2016 (iv) All of these
Rapid increase in population over a certain period (v) 18
of time is called population explosion.
110. Match the items given in column I with those of
104. Name the resources which can be replenished by column II :
reproduction or recycling.
Column I Column II
Ans : MAIN 2018
1. Tubectomy (a) Population
Renewable resources. dynamics

105. How does condom prevent fertilization? 2. Demography (b) Termination of

pregnancy
Ans : COMP 2012
3. Abortion (c) Prevents
It stops meeting of sperm and egg and prevents ovulation
fertilization to take place.
4. Birth rate (d) Sterilization in
106. What is the present population of India and its females
ranking in the world? 5. Contraceptives (e) Natality
Ans : SQP 2011 Ans :
India has the second largest population in the 1. – (d); 2. – (a); 3. – (b); 4. – (e); 5. – (c)
world with a population of 1.21 billion.
111. Explain the following :
107. When is world population day observed and what (i) Age ratio
is its aim? (ii) Natality rate
Ans : COMP 2015 (iii) Physical enumeration
Ans : SQP 2020
It is celeberated on July 11 and seeks to raise
awareness of global population issues. (i) The number of individuals belonging to
different age groups is called age ratio.
108. Which countries have shown reduced population (ii) The number of offspring produced per unit
growth in a matter of 15 years? time per unit of population is termed natality.
Ans : SQP 2017
(iii) Physical enumeration is the estimation of
human population by physical counting of the
Germany, Italy, Japan and Russia. individuals per unit area. The Census Bureau
109. Choose the correct alternative : physically verifies the number of persons
living in each house.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 401

DIRECTION : Give the full form of the following and It is a process of tying of oviducts in females and
explain its meaning : sperm duct in males to block them with the help
of an instrument called laproscopy.
148. IUD
154. Spermicides
Ans : COMP 2019
Ans : MAIN 2010
IUD stands for Intra uterine device. It helps to
check pregnancy. It is a small device which is These are chemicals which kills sperms which
inserted into the uterus and hence no pregnancy. are generally available in the form of creams and
jellies
149. MTP
155. Contraceptive
Ans : SQP 2000
Ans : COMP 2015
MTP stands for medical termination of pregnancy.
It is method where the foetus is destroyed after These are methods of preventing pregnancy in
pregnancy has occurred. women. It includes devices for both males and
females.
150. Population density and Population explosion
Ans : SQP 2017 DIRECTION : Distinguish between the following :

Population Population 156. Differentiate between Population density and

Density Explosion population explosion.
(a) It is the total (a) It is the Ans : COMP 2020
number of phenomenon of Population density is the total number of
individuals in a rapid increase of individuals in a given geographic region at a time
given geographic population. while population explosion is the phenomenon of
region at a time. rapid increase of population.

151. Immigration and Emigration

DIRECTION : Define:
Ans : MAIN 2019

157. Population
Immigration Emigration
Ans : SQP 2023
(a) It is the addition (a) It is the
All the members of a given species occupying a
of individuals decrease in a
given area form a population.
to a population population due
who comes to to individuals 158. Demography
live from outside moving out of
the country. the country. Ans : MAIN 2011

Demography It is the statistical study of human

152. ZPG population with reference to size, density, etc.
Ans : COMP 2006 159. Growth rate
ZPG stands for zero population growth. In this Ans : SQP 2017
case the birth rate equals the death rate. Hence
no growth in population takes place. Growth rate It is the difference between birth rate
and death rate of a population.

DIRECTION : With reference to population control 160. Population growth

what is meant by the following terms : Ans : MAIN 2011

153. Laproscopy Population growth It is the rate of increase or

decrease in the number of individuals of the
Ans : SQP 2009 population in a specific period.
CH 12 : HUMAN POPULATION

130. Deforestation leads to ______. Ans : MAIN 2013

Ans : MAIN 2022

False. Deforestation leads to drought.

Drought 140. Fossil fuels are exhaustible.

131. Usage of condom is a type of ______ method. Ans : SQP 2017

Ans : SQP 2023

True

Barrier 141. Tidal energy is an example of non-conventional

source of energy.
132. Population increases in ______ ratio.
Ans : COMP 2019
Ans : COMP 2020
True
Geometrical

DIRECTION : Explain the terms:

DIRECTION : State whether the following are true
or false. If false, rewrite the correct statement. 142. Population dens

133. Mortality is the number of deaths per thousand of Ans : MAIN 2000

the population per decade. The total number of individuals per square
Ans : SQP 2021
kilometre in an area at a time.

False. Mortality is the number of deaths per 143. Natality

thousand of the population per year.
Ans : COMP 2001

134. Diaphragm is a contraceptive for females. It is the number of live births per 1000 people of
Ans : MAIN 2021
the population per year.

True. 144. Death rate

135. Tidal energy is a non-conventional source of Ans : SQP 2006

energy. Death rate is the number of deaths per thousand

Ans : COMP 2000
of the population per year.

True.
DIRECTION : Give the scientific term for the
136. Fossil fuels are inexhaustible resources. following:
Ans : MAIN 2005
145. The surgical method of sterilisation in the human
False. Fossil fuels are exhaustible resources. female.
137. Mortality is the number of deaths per thousand of Ans : COMP 2010
the population per decade. Tubectomy
Ans : COMP 2010
146. The number of live births per thousand people of
False. Mortality is the number of deaths per the population per year.
thousand of the population per year.
Ans : SQP 2015
138. Tubectomy is the surgical method of sterilisation Natality
in males.
Ans : SQP 2012
147. The number of people per square kilometre at any
given time.
False. Vasectomy is the surgical method of
sterilisation in males. Ans : MAIN 2016

Population density.
139. Afforestation leads to drought.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 403

172. What is induced abortion? Ans : COMP 2017

Ans : SQP 2021

These are contraceptives which are fitted in the
vagina that stop the implantation of the embryo.
If there is any genetic disorder in the embryo, e.g. Copper T.
it can be terminated by a trained doctor in a
hospital. This is known as induced abortion or 179. Mention three main reasons for the sharp rise in
medical termination of pregnancy. human population in the world.

173. Rapid rise of population demands the use of non- Ans : SQP 2019

conventional use of energy. Comment. (i) Advanced medical facilities.

Ans : SQP 2023
(ii) Increase in the food production
(iii) Fewer infant deaths.
Due to population explosion, fossil fuels such as
coal and petroleum are depleting fast. These are 180. Mention three reasons why the growth of
non-renewable sources of energy and also cause population has not been appreciably checked in
pollution. So, man must shift to the usage of India.
non-conventional sources of energy such as solar
Ans : COMP 2020
energy, tidal energy ,nuclear energy, biogas etc.
and their uses must be popularised. (i) Children are regarded as God’s gift.
(ii) Religious beliefs.
174. What factors govern the growth of population? (iii) Illiteracy.
Ans : MAIN 2011

(i) Birth rate

(ii) Death rate
(iii) Emigration and Immigration
THREE MARKS QUESTIONS
175. List three factors that have contributed to an
181. (i) What are the age restrictions for marriage by
increase in human population.
law for boys and girls in India?
Ans : SQP 2015 (ii) Name two surgical techniques (one for the
(i) Advancement in the medical science to check human male and another for the human
the diseases. female) that can be used to prevent pregnancy
(ii) Mechanized agriculture for more food in the female.
production. (iii) Give three advantages of a small family.
(iii) Industrialization. Ans : SQP 2010

176. What is census? (i) Boys – 21 years; Girls – 18 years

(ii) Male – Vasectomy; Female – Tubectomy
Ans : COMP 2017
(iii) (a) Children can receive all the basic needs of
It is the counting of existing population every 10 life. Living environment can be improved.
years at a fixed time as regards to name, age, sex, (b) Children can be provided with good
occupation, date of birth, matrimonial status, education, good health of mother and
race, religion, education, etc. child is ensured due to spacing between
children.
177. The need to limit the size of the family is more (c) Living standards of the family can be
vital today than ever. Give two reasons. high which is due to the reduction of
Ans : MAIN 2019 economical burden to the family.
Small family is a happy family. If population 182. Do you think that urbanization is eco-friendly?
increases at an alarming rate it may create many Give reasons for your answer.
consequences to the families and the society
like health problems, lack of education, poor Ans : COMP 2013

sanitation, lowering of standard of living, etc. Urbanization cannot be termed as totally eco-
friendly. Urbanization has brought in industries
178. What are IUCD’s? giving employment to people and improving their
CH 12 : HUMAN POPULATION

economical income. However, gases emitted by (i) From figure A, it is obvious that the
these industries causes pollution and building population is on the rise since 1911-20 and
of industrial areas also are one of the cause of has reached 1 billion by 1991-2001. However,
deforestation. Roads, dams, agricultural lands the growth rate % shows a dip in 1911-20,
requirement, increases with the growing demand 1941-51 and 1991-2001.
of population and that adversely affects the (ii) From figure B, the birth rate since 1901-11
environment ultimately. Sustainable development to 1991-2001 has shown a steady decline over
is a way to use and keep both environment and the years. The death rate between 1901-11
resources eco-friendly and 1911-20 has shown a sudden rise, after
which it has shown steady decline rate and
183. (i) From the graphs A and B given below, what between 1971-81, 1981-91, 1991-2001, the
do you understand about India’s population death rate seems almost constant from then
and birth and death rate? onwards. Therefore, the revolutions and
(ii) Industrial, scientific and agricultural awareness brought in rise in population.
revolutions are the reasons for rapid rise in
population. Explain briefly.

FIVE MARKS QUESTIONS

184. Observe the diagram A and B given below :

(i) Label the parts 1 - 5.

(ii) What does diagram A depict ?

(iii) What does diagram B depict ?
(iv) Comment on X and Y.
(v) State one function each of part 2 and 4.
Ans : MAIN 2010

(i) 1-Vas deferens; 2-Testes; 3-Oviduct; 4-Uterus;

5-Ovary.
(ii) Diagram A depicts Vasectomy (cutting and
tying of the vas deferens).
(iii) Diagram B depicts Tubectomy (cutting and
tying of the oviduct).
(iv) ‘X’ represents cut and tied end of vas deferens
which prevents the entry of sperms and
prevents pregnancy.
‘Y’ represents the cut and tied end of oviduct.
It prevents the entry of ovum into the duct
and thus prevents pregnancy.
(v) Part - 2 – To produce sperms and male sex
Ans : MAIN 2012 hormones.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 405

Part - 4 – It protects and provides nutrients 4. What is the relationship between biotic
etc. to the foetus. potential and population size?

185. (i) What is population growth curve? Ans :

1. Population explosion.
2. Better health care and increased agricultural
production.
3. It depletes resources and worsens health
conditions.
4. Biotic potential increases population size if
conditions allow.

187. A rural region in India is facing a population

explosion due to traditional beliefs and the desire
(ii) What does the two growth curves in A and B for large families. The government is conducting
represent? a study to identify key factors contributing to this
(iii) Explain the term carrying capacity. issue.
(iv) Briefly explain S and J growth curve. 1. List three factors responsible for population
Ans : COMP 2015 explosion in India.
2. How does illiteracy contribute to population
(i) It is plotting graphically, a growth curve of
growth?
population size against the timeline.
3. Why does the desire for a male child increase
(ii) A – J shaped growth curve.
population growth in some regions?
B – S shaped growth curve (sigmoid curve)
4. What role do better health care and
(iii) Carrying capacity: The maximum limit of an
immunization play in population growth?
ecosystem that can provide basic needs to a
population under certain conditions. Ans :
(iv) S growth curve: The growth curve at first 1. Illiteracy, traditional beliefs, and desire for a
shows slow growth of population and then male child.
fast growth but finally the growth rate slows 2. Illiteracy limits awareness of family planning
down due to several environmental factors. methods.
J growth curve: Sudden exponentially 3. Families may keep having children until a
increase in the population of species due to male is born.
good environmental conditions (in terms of 4. They reduce mortality and increase life
food, water and natural habitat) or a sudden expectancy.
drastic decline of species population due to
adverse conditions. 188. A couple in a developing country is seeking advice
on family planning. They are considering both
natural and artificial methods of contraception to
control the number of children they have.
CASE BASED QUESTION 1. What is natural family planning, and how
does it help control population?
2. Name two artificial methods of contraception
186. In a densely populated country, the government is suitable for males and females.
trying to understand the factors responsible for the 3. Why might some people prefer artificial
rapid increase in population. They are analyzing methods of contraception over natural
various factors contributing to population growth. methods?
1. What is the term used to describe a sharp, 4. What is vasectomy, and how does it contribute
prolific increase in the population of human to population control?
beings?
Ans :
2. Identify two primary reasons for the rise in
the global human population. 1. Avoiding sex during unsafe periods prevents
3. How does population density affect natural pregnancy.
resources and health? 2. Condoms for males and IUDs for females.
CH 12 : HUMAN POPULATION

3. Artificial methods are more reliable than

natural methods.
4. Vasectomy prevents sperm release, reducing
fertility.

189. A family with five children is facing several issues

related to their large size, including economic
pressure and poor health. They are struggling
to provide adequate education, nutrition, and
housing for their children.
1. What are two disadvantages of having a large
family?
2. How does a large family lead to malnutrition?
3. What impact does a large family have on the
education and social development of children?
4. How does economic pressure affect the overall
quality of life in a large family?
Ans :
1. Poor education and health for children.
2. Resources like food may be insufficient.
3. Children may be neglected in education and
social development.
4. Economic pressure leads to poor housing and
living conditions.

www.nodia.in
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 407

CHAPTER 13
HUMAN EVOLUTION

1. HUMAN EVOLUTION
Human evolution: is about the origin of human
beings. Their birth place was in Africa but spread
to almost all parts of the world.

1.1 Human Ancestors

(i) Australopithecus – are the immediate
ancestors of modern human being. They were
evolved in eastern Africa around four million
years ago.

(iii) Homo erectus : They originated in Africa and

distributed from there to other parts of the
world. They were the first hominine species
that had bipedal locomotion indistinguishable
from that of Homo sapiens. They had an
average cranial capacity of about 50 to1100
cc. Their brain size exceeded modern man.
Their canine teeth were larger than modern
man. They had a moderately taller posture.

They had a flat nose, a strongly projecting

lower jaw and brain case (cranium) was
about 1/3 the size of modern human brain.
Their brain size was usually less than 500cc.
Their canine teeth were reduced in size
compared to those of apes. The position of
foramen magnum showed evidence of bipedal
locomotion.
(ii) Homo habilis : They were the species of the
tribe Hominine lived in Eastern and Southern
Africa around 2.4 to 1.4 mya. They were called
handy man or skillful person. They developed
from Australopithecus. They show definite
obligate bipedalism. They had protruding (iv) Neanderthals : They were largely related to
jaws with large molars, no chin, thick brow human. They were evolved between 500000
ridges and low skull. The brain size was and 600000 mya. They lived in Europe and
between 650 and 1300cc. They were smaller South west Asia. They showed bipedalism and
than modern man. The cranial capacity walked upright. They had a cranial capacity
slightly more than 500cc. The cranial base of 1300-1600cc, i.e. larger than modern man.
was narrow and elongated. They had large brains, angled cheek bones,
CH 13 : HUMAN EVOLUTION

huge nose, short stocky physique and their

average height was 155 cm (1.5 m).

1.2 Theories of Evolution

(a) Lamarck’s theory of inheritance of acquired
characteristics: He published his findings in
(v) Cro-Magnon : They were the first early
1801. He stated that if an organism changes
human. They lived about 30000 mya. They
to adapt to its environment,those changes are
lived in Europe. The skull was rounded with a
passed on to its offspring. A more frequent
near vertical forehead, a large brow ridge, no
and continuous use of any organ gradually
prominent prognathism of the face and jaw,
strengthens, develops and enlarges that organ
hard thicker teeth. Brain size 1660cc. Their
while permanent disuse of any organ weakens
forehead rises sharply, small brow ridges,
and deteriorates it.
prominent chin, forehead straight, location
of the foramen-magnum, curvature of spine
support bipedalism.

Theory of use and disuse: He theorised that

organisms develop characteristics that they
use and lose characteristics that they do rift
use, e.g., The ancestors of giraffe were bearing
a small neck and forelimbs and were horses-
(vi) Modern man (Homo sapiens sapiens): The like. When the surface vegetation become less,
species to which all modern human beings they had to stretch their neck and forelimbs
belong. Carolus Linnaeus applied the name to take the leaves which resulted in the slight
Homo sapiens. They lived around 2 mya. elongation of these parts. This trait was
They emerged in Africa. These species have passed on to the next generation with result
cranium high, rounded with thin bones, of long necked and long fore-limbed giraffe
reduced face, small pronounced brow ridge. was developed.
The chin was complex. They gathered and (b) Vestigial organs: There are the organs that
hunted food. Their jaws are less heavily are no longer used and are non-functional.
developed with smaller teeth. They have a These are reduced and modified version of an
lightly built skeleton. ancestral organs. The examples are:
(i) Vermiform appendix: It is a narrow blind
tube protruding from the coevum and
is located in the right-hand part of the
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 409

abdomen. In humans, the appendix has white moth did not survive. This is a particular
lost all or most of the original function type of natural selection.
through evolution. However in other
animals it has digestive function.
(ii) Wisdom teeth are the third and final set
of molars. Most people get them in their
early twenties. In some people, molar
teeth are useful while for other, if they White-winged and Dark-winged moths (a) Before
do not come through properly they may Industrialisation, (b) After Industrialisation
need to be removed.
(iii) Pinnae or outer ears are the external
parts of the ear in humans. Pinnae do
not have any function. In other animals
they move to detect sound. The muscles
of pinnae are vestigial since we cannot
move pinnae.
Various stage of man and Evolutionary

Major changes that took place from ape form to

human are:
1. Chin development
2. Reduced body hair
3. Bipedal locomotion and erect posture.
4. Cranial shows increasing capacity.
5. Increase in height.
(c) Darwin’s theory of evolution: Charles Darwin
6. Size of canine teeth reduced.
was a British naturalist who proposed the
theory of natural selection. He defined natural
selection as the principle by which each slight
trait, if useful is preserved by nature. In his MULTIPLE CHOICE QUESTION
book ‘Origin of the species’ published in 1859,
described survival of the fittest as mechanism
of natural selection that is reproductive 1. While studying the stages in the evolution of
success. man, a well-developed chin is observed in
Example 1: (a) Homo habilis
(b) Homo erectus
(c) Homo sapiens
(d) Australopithecus
Ans : SQP 2025

Thus (c) is correct option.

2. Industrial Melanism was observed in:

(a) Mice
(b) Peppered moth
(c) House flies
Example 2:
(d) Crow
Peppered moth. Bernard Kettlewell investigated
the evolutionary mechanism behind peppered Ans : MAIN 2024
moth before industrialisation and after Industrial Melanism was observed in the peppered
industrialisation. It is found in two varieties, light moth. This phenomenon refers to the evolutionary
gray and dark gray. They are nocturnal in nature. adaptation of the moth's coloration in response
The dark coloured moths was found to survive to environmental changes, particularly pollution
and reproduce due to the dark colour trunk of from industrial activities.
the tree caused by industrial pollution while the Thus (b) is correct option.
CH 13 : HUMAN EVOLUTION

which marked a crucial step in human evolution, Ans : SQP 2000

as it allowed for more efficient movement and Homo erectus had a cranial capacity ranging from
freed the hands for tool use. 850-1000 cc, indicative of advanced cognitive
Thus (c) is correct option. abilities compared to earlier ancestors, marking
an important stage in human evolution.
19. Most of the cave paintings discovered are Thus (d) is correct option.
associated with.
(a) Homo erectus 23. Bipedal locomotion offered evolutionary benefits
(b) Cro-Magnon man to early humans, enhancing their adaptability.
(c) Neanderthal man Identifying its primary advantage sheds light
(d) Dryopithecus on significant survival adaptations. The major
Ans : COMP 2019
advantage of bipedal locomotion is that it.
(a) releases the forelimbs for other better
Cro-Magnon man is known for creating intricate functions
cave paintings, showcasing advanced cultural (b) increases speed
and artistic skills that reflect their cognitive and
(c) reduces body weight
expressive abilities.
Thus (b) is correct option. (d) provides better body support
Ans : COMP 2010
20. The name Homo Sapiens can be assigned to.
(a) Java man Bipedalism allowed early humans to free their
(b) Peking man hands, enabling complex tasks like tool use, which
(c) Cro-Magnon man was crucial for survival.
(d) Shivalik man Thus (a) is correct option.

Ans : SQP 2021 24. Australopithecus, an important ancestor in human

Cro-Magnon man is considered an early form of evolution, is referred to as the "Southern ape"
Homo sapiens due to his anatomical similarities due to its unique combination of traits, reflecting
to modern humans and his advanced cultural both primitive and advanced characteristics.
practices, such as art and tool use. Australopithecus is also known as Southern ape,
Thus (c) is correct option. because it had.
(a) ape-like characters
21. According to Lamarck, well-developed auricle (b) man-like characters
muscles of rabbit have evolved due to. (c) Both (a) and (b)
(a) internal vital force (d) monkey-like characters
(b) continous use
(c) increasing need Ans : SQP 2017
(d) All of these Australopithecus exhibited both ape-like and
Ans : COMP 2023 man-like traits, showing primitive characteristics
alongside bipedalism, which linked it closely to
Lamarck theorized that traits such as the auricle
human ancestry.
muscles in rabbits evolved through internal forces,
Thus (c) is correct option.
constant use, and a growing need to adapt to their
environment. 25. Industrial melanism, a phenomenon observed in
Thus (d) is correct option. response to environmental changes during the
Industrial Revolution, provided insights into
22. In a study of human evolution, researchers found
natural selection by studying a specific organism
that an ancestor species exhibited a cranial
that exhibited color variations. The organism
capacity of approximately 850-1000 cc. This
studied for Industrial melanism was a.
information helps in identifying the cognitive
(a) Moth
development and lifestyle adaptations of early
(b) Butterfly
humans. The human ancestor who has a cranial
(c) Honey bee
capacity of 850-1000 cc.
(d) Cockroach
(a) Homo Habilis (b) Cro-Magnon
(c) Homo sapiens (d) Homo erectus Ans : COMP 2010
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 411
Ans : COMP 2019 Ans : SQP 2007

Ramapithecus is considered a pre-human ancestor Darwin’s theory of natural selection explains

due to its primitive features, marking an early evolution as a process where organisms with
stage in human evolutionary history before the favorable traits are more likely to survive
emergence of later hominids. and reproduce, passing these traits to future
Thus (b) is correct option. generations.
Thus (a) is correct option.
11. The false statement about Cro-Magnon man is
(a) he walked erect and was swift 15. Darwin’s theory of evolution fails to explain the.
(b) he was intelligent and cultured (a) role of environment
(c) his cranial cavity was less than Homo sapiens (c) overproduction
(d) he started metal work, painting and farming (c) survival of the fittest
(d) origin and transmission of variations
Ans : SQP 2021

Cro-Magnon man, an early form of modern Homo Ans : SQP 2015

sapiens, exhibited several advanced characteristics Darwin’s theory did not address how variations
that differentiated him from earlier ancestors. originate and are transmitted across generations,
However, certain statements about him do not as genetic mechanisms were not understood at
align with historical findings. the time.
Thus (c) is correct option. Thus (d) is correct option.

12. The human ancestor who was called as handy 16. The theory of Natural Selection was proposed by.
man. (a) Mendel
(a) Homo erectus (b) Neanderthals (b) Lamarck
(c) Cro-Magnon (d) Homo-Habilis (c) Darwin
(d) Wallace
Ans : MAIN 2000

Homo habilis, known as the "handy man," was Ans : COMP 2005

among the first to use stone tools, marking Charles Darwin proposed the theory of natural
a significant development in early human selection, describing how organisms with beneficial
technological skills. traits are more likely to survive and reproduce,
Thus (a) is correct option. passing these traits to future generations.
Thus (c) is correct option.
13. Lamarckism fails to explain which of the following
phenomenon? 17. The common ancestor to both man and ape is.
(a) Absence of all the four limbs amongst (a) Australopithecus
amphibians (b) Homo erectus
(b) Exceptionally long neck of giraffe (c) Sinanthropus
(c) Loss of vision in cavedwelling mammals (d) Dryopithecus
(d) An intellectual person having a dull son
Ans : MAIN 2010
Ans : COMP 2005
Dryopithecus is considered a common ancestor
Lamarckism cannot explain why an intellectual to both humans and apes, displaying primitive
parent might have a less intelligent child, as characteristics that diverged into separate
intelligence is influenced by both genetics evolutionary paths for these species.
and environment, not directly by acquired Thus (d) is correct option.
characteristics.
Thus (d) is correct option. 18. The speices that showed obligate bipedalism.
(a) Australopithecus
14. Darwin proposed the theory of origin of species (b) Neanderthals
by. (c) Homo Habilis
(a) natural selection (d) Homo erectus
(b) hybridisation
Ans : SQP 2017
(c) mutation
(d) acquired characters Homo erectus displayed obligate bipedalism,
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ENGLISH LITERATURE COMMERICAL

LANGUAGE IN ECONOMICS STUDIES
Class 10
ENGLISH Class 10 Class 10
Class 10

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94142 43489
CH 13 : HUMAN EVOLUTION
Ans : Raj said: "Lamarck’s theory of inheritance and
Modern humans (Homo sapiens sapiens) developed Darwin’s theory of natural selection."
a chin and reduced body hair, while Homo erectus Sonu said: "Darwin’s theory of survival of the
was the first species to show bipedal locomotion fittest and Lamarck’s theory of evolution through
and an increase in brain size. vestigial organs."
Thus (c) is correct option Lata said: "Darwin’s theory of natural selection
and Kettlewell’s theory of moth evolution."
Abhay said: "Lamarck’s theory of use and disuse
DIRECTION : Conversation Type Question
and Darwin’s theory of natural selection."
Who were correct?
31. A biology teacher asked her students to match the
(a) Raj and Abhay
human ancestors with their characteristics.
(b) Sonu and Lata
Raj said: "Homo habilis – called handy man and
(c) Lata and Abhay
had protruding jaws."
Sonu said: "Neanderthals – had a cranial capacity (d) Raj and Sonu
larger than modern humans." Ans :
Lata said: "Homo erectus – the first species to
Raj and Abhay both correctly identified Lamarck’s
show bipedalism like modern humans."
theory of inheritance of acquired characteristics
Abhay said: "Australopithecus – had large canine
and Darwin’s theory of natural selection as valid
teeth and a brain size greater than 1000 cc."
evolutionary theories.
Who were correct?
Thus (a) is correct option.
(a) Raj and Abhay
(b) Sonu and Lata 34. A teacher asked her students to match the
(c) Lata and Abhay following species with their brain sizes.
(d) Raj and Sonu Raj said: "Australopithecus – 500 cc."
Ans : Sonu said: "Homo erectus – 800 cc."
Lata said: "Neanderthals – 1300-1600 cc."
Sonu correctly mentioned Neanderthals' large Abhay said: "Homo habilis – 1100 cc."
cranial capacity, and Lata accurately identified Who were correct?
Homo erectus as the first species to exhibit (a) Raj and Lata
bipedal locomotion similar to modern humans.
(b) Sonu and Abhay
Thus (b) is correct option.
(c) Lata and Abhay
32. A teacher asked her students to identify two (d) Raj and Sonu
vestigial organs in humans. Ans :
Raj said: "Vermiform appendix and wisdom
teeth." Raj correctly identified Australopithecus with
Sonu said: "Pinna and canine teeth." 500 cc brain size, and Lata correctly identified
Lata said: "Wisdom teeth and pinnae." Neanderthals with 1300-1600 cc brain size.
Abhay said: "Pinna and large intestine." Thus (a) is correct option.
Who were correct? 35. A teacher asked her students to describe two
(a) Raj and Lata major evolutionary changes in humans from apes.
(b) Sonu and Abhay Raj said: "Development of chin and reduction of
(c) Lata and Abhay body hair."
(d) Raj and Abhay Sonu said: "Bipedal locomotion and development
Ans : of canine teeth."
Raj and Lata correctly identified the appendix, Lata said: "Increase in cranial capacity and
wisdom teeth, and pinnae as vestigial organs, while reduction of body hair."
Sonu and Abhay provided incorrect examples. Abhay said: "Increase in height and larger brow
Thus (a) is correct option. ridges."
Who were correct?
33. A teacher asked her students to list two theories (a) Raj and Lata (b) Sonu and Abhay
of evolution. (c) Lata and Abhay (d) Raj and Sonu
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 413

The peppered moth was studied for Industrial Ancestor Physical Feature
melanism, as its color variations demonstrated
how environmental changes influenced survival P Protruding jaws, no chin, and
through natural selection. large molars.
Thus (a) is correct option. Q Short, stocky physique and angled
cheekbones
DIRECTION : Matching type Question : Identify the correct pair of ancestors:
(a) P – Homo habilis, Q – Neanderthals.
26. Lata tried to match human ancestors with their (b) P – Cro-Magnon, Q – Australopithecus.
brain sizes. She tabulated the pairs as follows: (c) P – Homo erectus, Q – Neanderthals.
(d) P – Homo sapiens, Q – Homo habilis.
Theory Description Identify the correct pair of ancestors:
P Between 500-650 cc Ans :
Q 1300-1600 cc Homo habilis had protruding jaws, large molars,
Identify the correct pair of ancestors: and no chin, while Neanderthals had a stocky
(a) P – Australopithecus, Q – Homo habilis. build and prominent cheekbones.
(b) P – Homo habilis, Q – Neanderthals. Thus (a) is correct option.
(c) P – Homo erectus, Q – Cro-Magnon.
29. Sonu tried to match human ancestors with their
(d) P – Australopithecus, Q – Neanderthals. regions of origin. He tabulated the pairs as follows:
Ans :
Ancestor Region of Origin
Homo habilis had a brain size of about 500-650 cc,
P Lived in Easteern and Southern
while Neanderthals had a brain size of 1300-1600
Africa.
cc, which is larger than modern humans.
Thus (b) is correct option. Q Lived in Europe and Southern
Africa.
27. Abhay tried to match evolutionary theories with Identify the correct pair of ancestors:
their descriptions. He tabulated the pairs as (a) P – Homo sapiens, Q – Homo habilis.
follows: (b) P – Australopithecus, Q – Neanderthals.
Theory Description (c) P – Homo habilis, Q – Cro-Magnon.
(d) P – Homo erectus, Q – Australopithecus.
P Organisms develop characteristics
by using certain body parts more Ans :
Q Traits beneficial for survival are Australopithecus originated in Eastern and
passed on to offspring. Southern Africa, while Neanderthals lived in
Europe and Southwest Asia.
Identify the correct pair of theories:
Thus (b) is correct option.
(a) P – Darwin’s theory, Q – Lamarck’s theory.
(b) P – Lamarck’s theory, Q – Darwin’s theory. 30. Lata tried to match human ancestors with their
(c) P – Darwin’s theory, Q – Kettlewell’s theory. brain sizes. She tabulated the pairs as follows:
(d) P – Kettlewell’s theory, Q – Lamarck’s theory.
Change Description
Ans : P Development of chin and reduction
Lamarck's theory focuses on the use and disuse in body hair.
of organs, while Darwin’s theory explains natural Q Bipedal locomotion and increase in
selection where beneficial traits are passed on to cranial capacity.
future generations.
Thus (b) is correct option. Identify the correct pair of changes:
(a) P – Modern humans, Q – Australopithecus.
28. Raj tried to match human ancestors with their (b) P – Homo habilis, Q – Homo erectus.
physical features. He tabulated the pairs as (c) P – Modern humans, Q – Homo erectus.
follows: (d) P – Homo sapiens, Q – Neanderthals.
CH 13 : HUMAN EVOLUTION

86. Which creature was closely related to humans? Wisdom teeth are the third set of molars beneficial
When did they evolve? for our ancestors early diet of coarse, rough food
which require more chewing power and resulted in
Ans : SQP 2021
excessive wear of the teeth.
Neanderthals – They evolved around 500000 to
600000 mya. 92. Explain Natural selection.
Ans : MAIN 2019

Charles Darwin proposed the theory of natural

TWO MARKS QUESTIONS selection. It is defined as the principle by which
each slight trait, if useful is preserved by selectively
reproducing changes in its genotype.
87. Explain the theory of inheritance of acquired
93. State the two features of Australopithecus.
characters.
Ans : SQP 2020
Ans : COMP 2000
(i) The brain size of Australopithecus was less
The theory states that if an organism changes
than 500cc.
to adapt to its environment, those changes are
(ii) Their canine teeth was smaller than apes.
passed on to its offspring, i.e. Physiological
changes acquired over the life of an organism may 94. When did Cro – Magnon man appear? State the
be transmitted through offspring. distinguishing features of them.
88. Taking an example explain the theory of use and Ans : MAIN 2010

disuse. They appeared about 30000 mya.

Ans : SQP 2001 (i) They had a large brow ridge.,
(ii) Their skull was rounded.
The theory of use and disuse was proposed by
(iii) They had thicker teeth.
Lamarck. He theorised that organism loose
characteristics they do not require and developed 95. Study the figure and answer the following.
characteristics that are useful, e.g. The neck of
giraffe was long because it stretched to reach
leaves on high trees.

89. Define evolution.

Ans : MAIN 2005

Evolution is the gradual change in the heritable

characteristics of organisms from a simple to a
more complex form.

90. With respect to disuse of organs, explain

vermiform appendix and wisdom teeth.
Ans : SQP 2015

Wisdom teeth probably once served a function. (i) What is shown in the figure?
But the human jaw and wisdom teeth has become (ii) State their features.
smaller overtime the wisdom teeth nowhere to
grow. Ans : COMP 2012

Vermiform appendix is a small pouch attached (i) Homo erectus.

to large intestine, the junction of small intestine, (ii) Their cranial capacity was about 850 to
no longer aids in digestion. 1000cc. Their hip bones were smaller than
modern man. They had large canine teeth.
91. What function did the wisdom teeth perform?
96. Taking example of giraffe, explain use and disuse
Ans : COMP 2017
of organs.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 415
Ans : 44. The human ancestor who had rounded skull and
Raj correctly identified chin development and a vertical forehead.
reduced body hair, and Lata correctly mentioned Ans : SQP 2005
the increase in cranial capacity and reduction in
body hair as major evolutionary changes. Cro-Magnon
Thus (a) is correct option.
45. The name Homo sapiens to human beings was
given by –
Ans : COMP 2010
ONE MARK QUESTIONS Carolus Linnaeus

46. Handy man of the human ancestor.

DIRECTION : Name the following:
Ans : SQP 2011

36. The birth place of human beings. Homo habilis

Ans : SQP 2020 47. The scientific name of human being.

Africa Ans : MAIN 2015

37. The person who proposed the theory of use and Homo sapiens
disuse of organs.
48. The human ancestor who had reduced canine
Ans : COMP 2000
teeth.
Jean Baptiste de Lamarck
Ans : COMP 2015

38. The theory of natural selection was written by – Australopithecus.

Ans : SQP 2006
49. The structure which is an evidence of bipedal
Charles Darwin locomotion.
39. Who wrote Origin of species? Ans : SQP 2017

Ans : MAIN 2011 Foramen magnum.

Charls Darwin 50. A vestigial organ in human.
40. The immediate ancestor of modern human being. Ans : MAIN 2019

Ans : COMP 2017 Vermiform appendix

Cor-Magnon man 51. The birth place of human beings.
41. The human ancestor who lived in Eastern and Ans : COMP 2021
Southern Africa.
Africa
Ans : SQP 2019

Homo habilis DIRECTION : Choose the correct option from the

brackets and complete.
42. The first hominine who shows bipedal locomotion.
Ans : MAIN 2000 52. The species of human being who lived around 2
Homo erectus mya.
(Cro-Magnon, Homo sapiens, Neanderthals,
43. The first human ancestor who walked upright. Homo erectus).
Ans : COMP 2001 Ans : SQP 2000

Neanderthals Homo sapiens

CH 13 : HUMAN EVOLUTION

53. The species that showed obligate bipedalism. 61. Who had small pronounced browridge and
(Australopithecus, Homo habilis, Neanderthals, reduced face?
Homo erectus). (Neanderthals, Homo sapiens, Cro–Magnon,
Homo erectus.)
Ans : MAIN 2010

Homo habilis Ans : COMP 2015

Homo sapiens.
54. The human ancestor who was called as handy
man.
(Homo erectus, Neanderthals, Cro-Magnon, DIRECTION : Complete the following:
Homo habilis)
62. The example given by Lamarck for his theory use
Ans : COMP 2018
and disuse is______.
Homo habilis
Ans : SQP 2017

55. The human ancestor who had a cranial capacity Giraffe

of 850-1000 cc.
(Homo habilis, Homo erectus, Homo sapiens, Cro- 63. ______was Charles Darwin’s book.
Magnon) Ans : MAIN 2019

Ans : MAIN 2019 Origin of species

Homo erectus.
64. The brain size of Cro-Magnon was______cc.
56. The first huminine species who showed bipdalism. Ans : COMP 2011
(Homo habilis, Cro-Magnon, Neanderthalas,
1350
Australopithecus)
Ans : COMP 2012 65. Angled cheek bones were found in______.
Homo habilis Ans : SQP 2013

Neanderthals
57. The immediate ancestor of human being.
(Homo habilis, Australopithecus, Neanderthals, 66. ______showed obligate bipedalism.
Cro – Magnon)
Ans : MAIN 2015
Ans : SQP 2015
Homo habilis
Australopithecus
67. ______wrote ‘Origin of species’.
58. The theory of use and disuse was proposed by.
(Charles Darwin, Lamarck, Carl Linnaeus, Ans : COMP 2011

Aristotle) Charles Darwin

Ans : COMP 2017
68. The theory of acquired inheritance was proposed
Lamarck. by______.

59. A human ancestor who had large molars and no Ans : MAIN 2017

chin. Lamarck
(Australopithecus, Cro-Magnon, Homo habilis,
Neanderthals). 69. ______was called as skillful person.

Ans : SQP 2019 Ans : COMP 2019

Homo habilis Homo habilis

60. The cranial capacity of Neanderthals. 70. The brain size of Neanderthals was______.
(1600cc, 850cc, 100cc, 500cc) Ans : SQP 2011

Ans : MAIN 2011 1400cc.

1600cc
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 417

DIRECTION : Give technical term: 77. State Mendel's Law of Segregation

Ans : SQP 2025
71. The gradual change in the heritable traits of
organism from a simple to a more complex form. The two members of a pair of factors separate
during gamete formation.
Ans : COMP 2015

Evolution 78. What is natural selection by Darwin ?

Ans : MAIN 2008

DIRECTION : Distinguish between the following on Natural selection is the principle by which each
the basis of what is given in the brackets. slight variation of a trait is useful, is preserved.

72. Differentiate between the terms Phenotype and 79. What is evolution?
Genotype Ans : SQP 2011

Ans : SQP 2025 Evolution is the gradual change in the heritable

Phenotype — It is the observable characteristic characteristics of organisms from a simple to a
which can be controlled genetically. more complex form.
Genotype — It is the set of genes present in the 80. State the features Neanderthals with respect to
cells of an organism. bipedalism, cranial capacity and chin.
73. Homo erectus and Homo habilis (cranial capacity). Ans : COMP 2015

Ans : MAIN 2013 Neanderthals walked upright and showed

Homo erectus had an average cranial capacity bipedalism. They had a cranial capacity of 1600cc
of about 850 to 1000 cc. Homo habilis cranial and had angled cheek bones.
capacity between 750 to 1225 cc. 81. Mention the period of living of Australopithecus
74. Australopithecus and Neanderthals (period of and Homo erectus.
living). Ans : SQP 2010

Ans : SQP 2010 Australopithecus lived around 5 million years ago.

Australopithecus They lived around four million Homo erectus lived around 1.7 million years ago.
years ago. 82. How old is human evolution?
Neanderthals They lived around 500000 to 600000
years ago. Ans : MAIN 2016

Humans first evolved in Africa. They lived

75. Homo erectus and Homo habilis (canine teeth). between 6 and 2 mya.
Ans : COMP 2000
83. Give some characteristics of Homo sapiens.
Homo erectus had large canine teeth. Homo
habilis had small canine teeth. Ans : COMP 2015

(i) Large and complex brain.

DIRECTION : Answer the following: (ii) Ability to communicative in any language.
(iii) Ability to thinking and capable of reasoning.
76. Arrange and rewrite the terms in each group 84. What was the earlist defining human trait?
in the correct order to be in a logical sequence
beginning with the term that is underlined: Ans : MAIN 2017

Australopithecus, Cro-Magnon, Homo enxtus, Bipedalism.

Neanderthal man.
85. Name the book of Lamarck in which he had
Ans : MAIN 2024
written the theory of evolution.
Australopithecus, Homo erectus, Neanderthal
Ans : COMP 2019
man, Cro-Magnon
Philosophic Zoologique.
CH 13 : HUMAN EVOLUTION

3. Assertion (A) : Sympathetic nervous system Ans : MAIN 2007

prepares the body for violent action against Homo erectus lived around 2 million years ago
abnormal conditions. and exhibited notable developments in tool-
Reason (R) : Sympathetic nervous system making and adaptability, marking a pivotal stage
accelerates heartbeat. in the evolutionary history of humans.
Which of the following is correct? Thus (a) is correct option.
(a) Both Assertion and Reason True
(b) Assertion is True, Reason is False 7. Darwin in his ‘natural selection theory’ did not
(c) Assertion is False but Reason is True believed in any role of which one of the following
(d) Both Assertion and Reason are False in organic evolution?
(a) Parasites and predators as natural enemies
Ans : MAIN 2024
(b) Discontinous variations
The sympathetic nervous system prepares the (c) Survival of the fittest
body for action in response to stress or danger, (d) Struggle for existence
including an increase in heart rate to supply
Ans : SQP 2015
more oxygenated blood to the muscles and organs
involved in the response. Darwin’s theory focused on gradual changes
Thus (a) is correct option. through continuous variations, rejecting abrupt,
discontinuous variations as a mechanism in
4. The first scientist who proposed his theory for the natural selection.
evolution was. Thus (b) is correct option.
(a) Darwin
(b) Mendel 8. Concept of inheritance of acquired characters was
(c) Wallace disapproved by the experiments of.
(d) Lamarck (a) Weismann
(b) Oparin
Ans : MAIN 2001
(c) Fox
Lamarck was the first to propose a formal theory (d) Darwin
of evolution, suggesting that organisms evolve by
Ans : COMP 2011
acquiring traits during their lifetime and passing
them on, which influenced later evolutionary Weismann’s experiments disproved the inheritance
studies. of acquired traits, showing that changes acquired
Thus (d) is correct option. in an individual’s lifetime do not pass on
genetically to the next generation.
5. In the evolution of man, Homo erectus is Thus (a) is correct option.
considered to be evolved from.
(a) Dryopithecus 9. Lamarck’s theory of evolution is also called as
(b) Ramapithecus (a) theory of natural selection
(c) Cro-Magnon (b) survival of the fittest
(d) Australopithecus (c) theory of special creation
(d) inheritance of acquired characters
Ans : SQP 2005
Ans : MAIN 2019
Homo erectus evolved from Australopithecus,
showcasing developments in bipedalism and Lamarck’s theory, known as "inheritance of
tool use, which marked a key step in the human acquired characters," suggested that traits
evolutionary trajectory. developed during an organism’s life could be
Thus (d) is correct option. passed to offspring, influencing evolution.
Thus (d) is correct option.
6. The species of human being who lived around 2
mya. 10. Identify the pre-human ancestor.
(a) Homo sapiens (a) Australopithecus
(b) Cro-Magnon (b) Ramapithecus
(c) Neanderthals (c) Neanderthal man
(d) Homo erectus (d) Cro-Magnon
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 419
Ans : SQP 2017

(i) The theory states that if an organism changes

to adapt to its environment, those changes
are passed on to its offspring.
(ii) Evolution is the gradual change in the
heritable characteristics of organisms from a
simple to a more complex form.

99. Distinguish between:

(i) Homo erectus and Homo habilis.
(ii) Australopithecus and Neanderthals.
Ans : MAIN 2019

(i) Homo erectus : Their cranial capacity was

750 to 1100cc. They had larger canine teeth.
(ii) Homo habilis : Their cranial capacity was
between 650 to 800cc. They had larger molars.
Australopithecus : Their cranial capacity was
Ans : SQP 2014 less than 500cc. They had smaller canine
Lamarck believed that organisms lose traits that teeth. Neanderthals : Their cranial capacity
they do not use, while they develop traits that was 1600cc. They had long pointed canine
they use, e.g. Giraffe stretched their neck to teeth.
reach the high leaves. Their off springs and later
generations inherited the resulting long necks.

97. Study the figure and answer: THREE MARKS QUESTIONS

100. The figure shows a human ancestor. Study it and

answer the following.

(i) Mention the scientific name of the, figure. (i) Identify the figure.
(ii) State its features. (ii) Mention the structures that support
Ans : MAIN 2015
bipedalism.
(iii) Where did they live?
(i) Homo sapiens.
(ii) Their cranium is high, rounded with thin Ans : COMP 2011

bones. They have small pronounced brow (i) Cro-Magnon.

ridges and show bipedalism. (ii) Location of foramen magnum and curvature
of the spine support bipedalism.
98. Define: (iii) They lived in Europe.
(i) The theory of inheritance of acquired
characteristics. 101. Study the skull of human ancestor and answer the
(ii) Evolution. following.
CH 13 : HUMAN EVOLUTION

defined natural selection as the principle by which

each slight trait, if useful is preserved by nature. In
his book ‘Origin of the species’ published in 1859,
described survival of the fittest as mechanism of
natural selection that is reproductive success, e.g.
Peppered moth. Bernard Kettlewell investigated
the evolutionary mechanism behind peppered
moth. It is found in two varieties, light gray and
dark gray. They are nocturnal in nature. The
dark coloured moths was found to survive and
reproduce due to the dark colour trunk of the tree
caused by industrial pollution while the white
moth slid not survive. This is a particular type of
natural selection.
(i) Identify the figure.
(ii) State the features of the figure.
Ans : MAIN 2014

(i) Australopithecus.
CASE BASED QUESTION
(ii) They had a flat nose, strongly projecting
lower jaw, their brain size was less than 500cc. 104. Australopithecus, one of the earliest human
Their canine teeth was reduced in size. They ancestors, evolved in Africa. They had small brains
showed bipedalism. and reduced canine teeth. Over time, species
like Homo habilis and Homo erectus appeared,
102. Study the figure:
showing increasing brain size and bipedalism.
1. What evolutionary change is seen in
Australopithecus?
2. How did Homo habilis differ from
Australopithecus?
3. What does bipedalism indicate about human
evolution?
4. Where did Australopithecus evolve?
Ans :
1. Reduced canine teeth and small brain size.
2. Homo habilis showed tool use and had a
slightly larger brain
3. It shows adaptation to walking on two legs.
4. Australopithecus evolved in Africa.
(i) What does the figure depict?
105. Homo habilis, an early ancestor, lived in Africa
(ii) State the features of it.
around 2.4 million years ago. They were the first
Ans : MAIN 2012 to show evidence of tool use and bipedalism,
(i) Homo habilis. marking a significant step in human evolution.
(ii) They showed obligate bipedalism. They had 1. What skill did Homo habilis develop?
protruding jaws. Their brain size was 750 to 2. What physical trait helped Homo habilis with
1225cc. bipedalism?
3. Where did Homo habilis live?
103. Explain natural selection by taking peppered 4. How long ago did Homo habilis exist?
moth as an example.
Ans :
Ans : COMP 2017
1. Tool use.
Charles Darwin was a British naturalist who 2. The position of the foramen magnum
proposed the theory of natural selection. He supported upright walking.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 421

3. Homo habilis lived in Africa.

4. Around 2.4 million years ago.

106. Homo erectus originated in Africa and spread to

other parts of the world. They had larger brains
than earlier ancestors and demonstrated advanced
bipedalism, which resembled modern humans.
1. Where did Homo erectus originate?
2. What advancement did Homo erectus show?
3. How did the brain size of Homo erectus
compare to earlier ancestors?
4. What was a key feature of Homo erectus?
Ans :
1. Homo erectus originated in Africa.
2. They had advanced bipedalism.
3. It was larger than earlier ancestors.
4. Upright walking and bipedalism.

107. Neanderthals lived in Europe and Asia and had

larger cranial capacities than modern humans.
They adapted to cold climates and had strong
physical features such as thick brow ridges and
stocky bodies.
1. Where did Neanderthals live?
2. What was the brain size of Neanderthals?
3. What physical adaptation helped
Neanderthals survive cold climates?
4. What feature distinguished Neanderthals?
Ans :
1. In Europe and Asia.
2. Larger than modern humans.
3. Their stocky, muscular bodies.
4. Thick brow ridges and large brains.

108. Cro-Magnon were early humans living in Europe

around 30,000 years ago. They had larger
brains than Neanderthals, prominent chins, and
demonstrated advanced tool-making and hunting
skills.
1. Where did Cro-Magnon live?
2. What was the brain size of Cro-Magnon?
3. What physical feature distinguished Cro-
Magnon?
4. What skill did Cro-Magnon develop?
Ans :
1. In Europe.
2. Larger than Neanderthals
3. Prominent chin and near-vertical forehead.
4. Advanced tool-making and hunting skills

www.nodia.in
CH 14 : POLLUTION

CHAPTER 14
POLLUTION

1. POLLUTION flora and fauna, acidification of lakes affecting

Pollution can be defined as an undesirable aquatic life, corrosion of marble buildings,
change in the physical, chemical or biological monuments, statues etc.
characteristics of environment. Pollution need not (iv) Oxides of N2, decrease the oxygen carrying
always be caused by chemical substances such capacity of blood.
as particulates (like smoke and dust). Forms of (v) Smoke and dust particles form a thin layer
energy such as sound, heat or light can also cause on the leaves to reduce light absorption
pollution. and hence photosynthesis, cause leaf fall in
Agents causing pollution are called pollutants. legumes, necrosis and chlorosis of margins and
Pollutant may be tips of leaves caused by hydrogen fluorides.
(i) Quantitative e.g. CO2 and (vi) Thinning of ozone layer by release of aerosols
(ii) Qualitative e.g. pesticides synthesized and such as CCl4, producing skin cancer and other
released by man eye disorders due to increased UV radiations.
Depending upon their ability to degrade, (vii)Smog containing secondary pollutants such as
pollutants can be classified as PAN, cause glazing, silvering and sometimes
(i) Biodegradable e.g. sewage, vegetable peels necrosis of sensitive species resulting in
etc. and. crop losses, Green house effect is a natural
(ii) Non-biodegradable e.g. DDT, plastic, glass, phenomenon which helps in heating the
etc. earth’s surface and atmosphere just right
(average 15°C), suitable for life on this planet.
2. TYPES OF POLLUTION CO2, H2O vapour and methane are the green
house gases producing this effect by radiating
As stated before, there are different types of
back the long wave radiations emitted from
pollution, which are either caused by natural
earth’s surface. Rise in CO2 content, due to
events (like forest fires) or by man-made activities
some human activities, have increased the
(like cars, factories, nuclear wastes, etc.) These
intensity of this effect, resulting in the rise of
are further classified into the following types of
global temperature called global warming. It
pollution:
may lead to melting of glaciers and polar ice
2.1 Air Pollution caps, thereby flooding of coastal plains.
Control of air pollution :
Air pollution is defined as the occurrence of
(i) Establishment of industrial estates away from
foreign particles or gases into the atmosphere
residential areas.
which are harmful to man, vegetation, animals
(ii) Compulsory use of filters, scrubbers and
and buildings.
electrostatic precipitator and catalytic
Sources of air pollution :
converters in automobiles.
Automobile exhaust, industrial waste (SO2, CO,
(iii) use of unleaded sulphur free gasoline.
CO2, H2S, NO, smoke, dust, fly ash etc.) burning
(iv) Afforestation and reforestation of waste lands
garbage, smoke from brick-kilns, thermal plants,
and the mining area on priority basis.
etc.
(v) Use of unconventional sources of energy.
Effects of air pollutants :
(i) Respiratory problems such as bronchitis, 2.2 Water Pollution
asthma and lung diseases
It is defined as the decrease in quality of water
(ii) Dioxin a harmful pollutant released during
by the presence of various solid and liquid wastes
garbage burning is a carcinogen.
(organic, inorganic biological, radiological) or
(iii) Acid rains, increase soil acidity affecting land
factor (heat) which degrades the quality of water
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 423

to make it unfit for human use. depletion and hence death of aquatic animals.
Major sources of water pollution : (vii) Radioactive wastes released in water bodies
Major Sources of water pollution can be are assimilated by aquatic organisms. They
categorized as: cause ionization of body fluids and mutations.
(i) Household detergents mainly composed of Control of water pollution :
phosphates. Control of water pollution can be done by.
(ii) Domestic sewage (human excreta, household (i) Recirculation of waste materials within the
wastes, kitchen washings, bathing, infectious industry.
agents for various diseases-bacteria, eggs of (ii) Recycling of waste such as gobar gas plant.
parasites and their cysts. (iii) Judicious use of fertilizers, weedicides and
(iii) Organic industrial wastes from tanneries, pesticides.
slaughter houses and canning industries. (iv) Sewage pollutants are subjected to primary
(iv) Industrial wastes from chemical, textile and treatment and secondary treatment, to make
distillery industries, include heavy metals it non-toxic before passing it in to lakes and
such as arsenic, cadmium, mercury, lead, rivers.
cyanides etc. (v) Reverse osmosis converts the sewage water
(v) Oil spills, during transportation and unloading into fairly clean drinking water.
of oil tankers. (vi) Thermal pollution can be reduced by using
(vi) Agricultural-run-off of herbicides, pesticides, cooling ponds, wet cooling towers etc.
fertilizer, etc.
(vii) Thermal pollution caused by addition of 2.3 Soil Pollution
heated gases or heated water or effluents and Soil pollution is defined as the decrease in soil
hot water bodies. fertility because of the addition of some foreign
(viii) Pollution of sea, due to direct dumping elements and factors. Soil erosion is caused by two
of industrial wastes from coastal industries, factors water and wind, Destruction of forests in
sewage of coastal cities. the catchment area of rivers by excessive felling
Effects of water pollutants : and overgrazing is the major cause.
Effects of water pollutants on the health of man Sources of soil pollution :
and other organisms : Sources of soil pollution are as follows :
(i) Pathogens contaminated water cause cholera, (i) Industrial wastes, both solids and liquids are
typhoid, amoebic dysentery jaundice and skin dumped over the soil. The wastes include toxic
diseases. chemicals, acids, alkalies, organic solvents.
(ii) Decomposition of organic wastes by microbes (ii) Surface mining and strip mining remove top
take up oxygen present dissolved in water soil and also spread mine dust over a large
resulting in death of aquatic animals. area during transportation.
(iii) Oil spills prevents the oxygenation of sea (iii) Urban, commercial and domestic wastes are
water, thereby affecting marine organisms. dumped in open areas inside and outside
(iv) Toxic chemicals such as DDT and heavy the city. The wastes include odd scraps,
metals released in water bodies, undergo bio- newspapers, wooden furniture, peelings of
magnification as they pass through successive vegetables and fruits, lawn trimmings, glass
tropic levels of a food chain. It adversely can, broken appliances, plastic etc.
effects the human beings and the population (iv) Agricultural chemicals such as pesticides,
of many birds. weedicides and fertilizers used to protect the
(v) Thermal pollution, cause deoxygenation. crops and increase the yield of crops, when
Thereby decrease in the rate of decomposition used in excess, cause deterioration of soil
of organic matter, replacement of green alga, structure, underground water, affects other
by less desirable, blue green algae, animals useful harmless insects beside killing target
fail to multiply thus adversely affecting flora insects, thereby producing adverse ecological
and fauna. effects of substances.
(vi) Flow of fertilizers rich water from fields to (v) Biomedical waste is another source of soil
water bodies results in eutrophication i.e. pollution.
algal bloom, which increase organic loading Effects of soil pollutants :
of water body. This further results in oxygen (i) The toxic industrial wastes convert the fertile
CH 14 : POLLUTION
Ans : Ans :
Pollution is described as an unwanted change Qualitative pollutants are man-made, like
affecting the environment’s physical, chemical, pesticides, while quantitative pollutants like CO2
or biological aspects, which can disrupt natural are naturally occurring substances in excess.
balance. Thus (b) is the correct option. Thus (c) is the correct option.

23. Ravi is learning about diseases and their 27. Biodegradable pollutants include:
causes. He finds that some illnesses spread due (a) Plastic and glass
to contaminated water, making it important to (b) Vegetable peels and sewage
identify such waterborne diseases. Which among (c) Pesticides and glass
the following diseases is caused by water pollution? (d) Plastic and sewage
(a) Measles
Ans :
(b) Tuberculosis
(c) Hemophilia Biodegradable pollutants are those that can
(d) Typhoid decompose naturally, like vegetable peels and
sewage, unlike non-biodegradable pollutants like
Ans : COMP 2018
plastic.
Typhoid is caused by consuming water Thus (b) is the correct option.
contaminated with bacteria, often due to poor
sanitation, making it a waterborne disease linked 28. What term is used for agents causing pollution?
to pollution. (a) Pollutants
Thus (d) is correct option. (b) Contaminants
(c) Toxins
24. Which of the following is NOT an example of a (d) Carcinogens
pollutant in the form of energy?
Ans :
(a) Sound (b) Heat
(c) Light (d) Dust Pollutants are substances or agents that cause
pollution, altering the environment’s physical,
Ans : chemical, or biological state undesirably.
While sound, heat, and light are energy forms Thus (a) is the correct option.
that can cause pollution, dust is a particulate
matter pollutant, not an energy form. 29. Rahul is studying waste management and learns
Thus (d) is the correct option. that non-biodegradable materials stay in the
environment, causing pollution over time. An
25. If DDT is sprayed in a lake, its highest example of non-biodegradable waste is :
concentration will be found in (a) Vegetable peels
(a) Phytoplanktons (b) Sewage
(b) Zooplanktons (c) Livestock waste
(c) Fishes (d) DDT
(d) Fish eating birds
Ans : COMP 2015
Ans : COMP 2017
DDT is non-biodegradable and persists in the
DDT concentration is highest in fish-eating birds environment, leading to long-term pollution and
due to bio-magnification, where toxins accumulate bioaccumulation.
at greater levels in organisms higher up the food Thus (d) is correct option.
chain.
Thus (d) is correct option. 30. Amit is studying the ozone hole and learns it has
harmful effects due to increased UV exposure on
26. Which of the following is an example of a Earth. Ozone hole results in
qualitative pollutant? (a) UV radiation reaching the earth
(a) CO2 (b) Increase in skin cancer
(b) Dust (c) Cataract
(c) Pesticides (d) All the above
(d) Water vapor
Ans : SQP 2011
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 425

called radioactive elements e.g. radium, thorium, MULTIPLE CHOICE QUESTION

uranium, etc.
Sources of radioactive pollution :
(a) Natural (Background) radiation. 1. The prime source of chlorofluorocarbons is :
(i) Cosmic rays from outer space. (a) Vehicular emissions
(ii) Terrestrial radiation from radioactive/ (b) Industrial effluents
radioisotopes present in earth e.g. (c) Domestic sewage
strontium, uranium, radium and caesium. (d) Refrigeration equipments
(b) Man-made radiation.
Ans : SPQ 2017
(i) mining and refining of plutonium,
thorium, caesium, uranium used in Refrigeration equipment is the main source
atomic i.e., power plants, nuclear weapon, of CFCs, which, when released, contribute
preparation of radioactive isotopes, significantly to ozone layer depletion.
nuclear fall out, X-rays etc. Thus (d) is correct option.
Effects of radioactive pollutants depend upon its
2. Which one of the following is a Greenhouse gas ?
(i) half life.
(a) Oxygen
(ii) energy releasing capacity.
(b) Methane
(iii) rate of diffusion.
(c) Sulfur dioxide
(iv) rate of deposition.
(d) Nitrogen
(v) climatic conditions.
All the organisms are affected by radioactive Ans : MAIN 2018
pollution to a varied degree. The actively Methane is a greenhouse gas that traps heat in
growing and dividing cells are quickly damaged the atmosphere, playing a significant role in the
by radiations. The various effects of radiation on greenhouse effect and global warming.
human beings include. Thus (b) is correct option.
(a) sun burn-causing reddening of skin and
blusters. 3. Which one the following is an example of
(b) Snow blindness-cornea turns opaque. pollutant?
(c) cancer-accumulation of strontium causes (a) A rat entering your kitchen.
bone cancer. (b) The dust raised during road-cleaning.
(d) Inactivation of biomolecules such as proteins, (c) CO2 given out by the respiring organisms.
RNA, DNA and pigments of plants. (d) The heat given out while cooking food.
(e) Genetic disorders are caused due to mutations
Ans : SPQ 2019
in DNA.
Control of radioactive pollution : involves Dust raised during road-cleaning disperses
measures such as particulate matter into the air, which can harm
(i) Leakage of radioactive materials from nuclear respiratory health and contribute to pollution.
reactors laboratories and industries using Thus (b) is correct option.
them should be totally checked.
4. Which of the following is a green house gas ?
(ii) Radioactive wastes disposal must be safe, by
(a) CO2
changing into harmless form or stored in safe
(b) O2
places, to decay in a harmless manner.
(c) Nitrogen
(iii) Preventive measures should be taken so that
(d) CO
natural radiation level does not rise above the
permissible limits. Ans : SQP 2000
(iv) Safety measures should be taken against CO2 is a greenhouse gas because it traps heat in
accidents in nuclear power plants. the Earth's atmosphere, leading to warming. It
(v) Workers using radio active materials should absorbs and re-radiates infrared radiation (heat)
wear protective garments. back towards the Earth's surface, creating the
greenhouse effect. In contrast, O2 and N2 do not
trap heat, and CO is not a significant greenhouse
gas.
Thus (a) is correct option.
CH 14 : POLLUTION

lands in to barren area. (iv) Industries.

(ii) Accumulated urban, commercial and (v) Electric appliances used in kitchen and
domestic wastes pollute the soil, become houses.
breeding ground for mosquitoes and flies, (vi) Agricultural machines like tractors, harvestors
emit foul smell due to decomposition, release etc
toxic acids that leach down the soil, destroy (vii) Operations such as blasting, bulldozing,
the vegetation. construction work, stone crushing etc.
(iii) Agricultural chemicals being persistent broad (viii) Public address systems such as loud speakers
spectrum affect other animals, man and and entertainment equipment like radios,
plants. They tend to accumulate inside living record players, musical bands, television sets,
organisms e.g. DDT and undergo biological etc.
amplification, proving fatal to higher trophic Effects of noise pollution include :
level animals especially fish and birds. (i) Temporary or permanent hearing loss due to
(iv) Untreated infected biomedical wastes help in continued high intensity noise. A sudden loud
spreading diseases, mix with soil and pollute noise may damage ear drum.
it. (ii) Cause anxiety and stress, blood pressure by
(v) Excessive use of fertilizers cause soil increasing cholesterol level.
deterioration through the decrease in natural (iii) Cause headache by dilating blood vessels of
bacterial population. the brain.
(vi) Mine dust destroys vegetation, cause (iv) Disturbs sleep and leads to nervous irritability.
deformities and diseases in animals and (v) Lowers efficiency of work.
human beings. (vi) Affects concentration of thought.
(vii) Acid rains cause soil pollution, kill the (vii) Interferes in communication.
essential soil microorganisms and induce Control of noise pollution :
toxicity in the soil for plant growth. (i) Aerodromes, Industrial zones should be far
Control of soil pollution : away from human settlements.
(i) Judicious use of agricultural pesticides and (ii) Proper lubrication and maintenance of
fertilizers. machines
(ii) Cropping techniques such as crop rotation (iii) Enclosure of machinery with sound absorb
and mixed cropping result in improving soil materials.
fertility. (iv) Protection of workers through devices such as
(iii) Improvement in mining techniques and ear muffs or cotton plugs.
transport of extracted materials. (v) Use of loudspeakers and amplifiers be
(iv) Restoring forests, grassland cover, controlled restricted to a fixed intensity and fixed hours
grazing check soil erosion, flood and water of the day.
logging. (vi) Blowing of horns should be totally banned
(v) Special pits or low lying areas in vacant, lands especially near hospitals and schools by
outside city be selected for dumping of non- creating silence zones.
biodegradable waste. Biodegradable wastes (vii) Creation of ‘Green belt’ vegetations and
be converted in to composite manures. open spaces in meteropolitan cities, along
(vi) Biomedical wastes should be incinerated. highway and streets are effective in absorbing
(vii) Recycling and recovery of wastes. and deflecting the noise upward in the air.
(viii) Legal enforcement of specific legislation and
2.4 Noise Pollution regulation on noise pollution.
Noise can be defined as unwanted sound which
interferes with human communication, comfort, 2.5 Radioactive Pollution
health, etc. Radioactive pollution is the physical pollution
Sources of noise pollution : contamination of air, water and soil with
Sources of noise pollution are as follows. radioactive materials.
(i) Automobiles, trains and other means of road Radioactivity is the property of certain elements
transportation. to spontaneously emit protons, electrons and
(ii) Jet airplane. gamma rays as a result of disintegration of atomic
(iii) work shops. nuclei. The elements which emit radiations are
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 427

14. An example of non-biodegradable waste Ans : SQP 2018

(a) Vegetable peels (b) Sewage DDT is a non-biodegradable waste, persisting in

(c) DDT (d) Livestock wastes the environment and causing bioaccumulation,
Ans : SQP 2009
which can be harmful to ecosystems.
Thus (c) is correct option.
DDT is a non-biodegradable waste, meaning
it does not decompose easily and can persist 19. The BS emission norms enforced for the entire
in the environment, leading to pollution and country on April 1st 2017 were -
bioaccumulation. (a) BS III
Thus (c) is correct option. (b) BS VI
(c) BS V
15. The gradual continuous increase in average (d) BS IV
temperature of surface of the earth as a result
of increase in concentration of CO2 and CFCs is Ans : COMP 2000

termed as BS IV emission norms were enforced across India

(a) Greenhouse effect on April 1st, 2017, aiming to reduce vehicular
(b) Global warming emissions and improve air quality.
(c) Ozone degradation Thus (d) is correct option.
(d) Montreal protocol
20. The noise level that may lead to pain and physical
Ans : MAIN 2010
discomfort is
Global warming refers to the rise in Earth's (a) 50 dB
surface temperature due to greenhouse gases like (b) 80 dB
CO2 and CFCs, contributing to climate change. (c) 120 dB
Thus (b) is correct option. (d) 60 dB

16. The greenhouse gases Ans : COMP 2010

(a) Decrease the temperature Noise levels around 120 dB can cause pain and
(b) Keep the planet warm discomfort, as this intensity is typically associated
(c) Radiate the heat of earth with harmful auditory and physical effects.
(d) Trap the harmful rays Thus (c) is correct option.
Ans : COMP 2015
21. Which one of the following is a greenhouse gas ?
Greenhouse gases keep the planet warm by (a) Methane
trapping heat in the atmosphere, maintaining (b) Oxygen
Earth’s temperature and supporting life. (c) Sulphur dioxide
Thus (b) is correct option. (d) Nitrogen

17. Which one is non-biodegradable? Ans : MAIN 2015

(a) DDT Methane is a powerful greenhouse gas that traps

(b) Vegetable peels heat in the atmosphere, contributing significantly
(c) Livestock waste to global warming and climate change.
(d) Sewage Thus (a) is correct option.
Ans : MAIN 2005
22. Pollution can be defined as :
DDT is non-biodegradable, meaning it remains (a) A desirable change in the biological
in the environment without decomposing, causing characteristics of the environment
prolonged pollution and bioaccumulation. (b) An undesirable change in the physical,
Thus (a) is correct option. chemical, or biological characteristics of the
environment
18. An example of non-biodegradable waste is (c) A natural change in the environmental
(a) Vegetable peels balance
(b) Sewage (d) A change in only the chemical characteristics
(c) DDT of the environment
(d) Livestock waste
CH 14 : POLLUTION

54. The primary source of air pollution in metropolitan Fertilizers

cities.
65. The biggest source of air pollution in big cities.
Ans : MAIN 2019
Ans : SQP 2000
Automobile pollution
Vehicles/automobiles
55. The main disease caused by air pollution.
66. The source of acid rain.
Ans : COMP 2020
Ans : MAIN 2005
Respiratory diseases such as bronchitis, asthma
and lung diseases are mainly caused by air SO2
pollution.
67. A greenhouse gas.
56. Two natural sources of pollution. Ans : COMP 2001

Ans : SQP 2023 CO2

Forest fires, volcanic eruptions, cyclones and
68. The major source of marine water pollution.
floods.
Ans : SQP 2009
57. A disease caused by air pollution.
Oil spills
Ans : COMP 2000
69. A disease caused due to water pollution.
Tuberculosis
Ans : COMP 2010
58. A green house gas.
Typhoid/Jaundice
Ans : MAIN 2005
70. An example of biodegradable pollutant.
CO2
Ans : SQP 2015
59. A poisonous allotropic form of oxygen.
Vegetable peel
Ans : COMP 2009
71. An example of non-biodegradable pollutant.
Ozone
Ans : MAIN 2010
60. The main source of water pollution.
DDT/plastic
Ans : MAIN 2010
72. The substance that cause pollution.
Sewage
Ans : COMP 2013
61. A disease caused by prolonged exposure to
Pollutants
radiation.
Ans : COMP 2015 73. An increase in the toxic materials at each level of
food chain.
Cancer
Ans : SQP 2016
62. The vehicular standard for controlling air
Biomagnification
pollution.
Ans : SQP 2019 74. The chemical that causes depletion of ozone layer.
Euro III. Ans : MAIN 2017

CFC
63. Two sources of water pollution.
Ans : MAIN 2020 75. A disease caused by prolonged exposure to
radiation.
Sewage, fertilizers
Ans : MAIN 2005
64. The cause of eutrophication in lake.
Cancer
Ans : COMP 2023
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 429

The ozone hole allows more UV radiation to reach 34. Sunil is learning about alternative fuels and comes
Earth, leading to skin cancer, cataracts, and other across Compressed Natural Gas (CNG), which is
environmental impacts. widely used as a cleaner fuel for vehicles. He wants
Thus (d) is correct option. to know its primary component. Compressed
Natural Gas (CNG) is
31. In the textbook, you came across Three Mile (a) Propane
Island and Chernobyl disasters associated with (d) Butane
accidental leakage of radioactive wastes. In India, (c) Ethane
we had Bhopal gas tragedy. It is associated with (d) Methane
which of the following?
(a) CO2 Ans : SQP 2008

(b) CFCs CNG primarily consists of methane, a cleaner-

(c) Methyl isocyanate burning fuel that reduces harmful emissions
(d) Methyl cyanate compared to conventional gasoline or diesel.
Ans : MAIN 2016
Thus (d) is correct option.

The Bhopal gas tragedy was caused by the

accidental release of methyl isocyanate gas, DIRECTION : Conversation Based Question
resulting in widespread illness and fatalities.
Thus (c) is correct option. 35. A teacher asked her students to name two non-
biodegradable pollutants.
32. Meena is studying greenhouse gases and learns Maya said : Plastic and Glass.
that certain gases trap heat in the Earth's Ajay said : Paper and Vegetable peels.
atmosphere, contributing to the greenhouse effect Tina said : DDT and Plastic.
and global warming. Which among the following Rohan said : Sewage and Wood.
is the main cause of ozone depletion? Who were correct?
(a) Sulphur dioxide (a) Maya and Ajay
(b) Carbon dioxide (b) Ajay and Rohan
(c) Nitrogen dioxide (c) Maya and Tina
(d) CFCs (d) Tina and Rohan
Ans : MAIN 2001 Ans : COMP 2019

CO2 is a greenhouse gas that traps heat in the Plastic, glass, and DDT are non-biodegradable.
atmosphere, playing a significant role in the Paper, vegetable peels, sewage, and wood are
greenhouse effect and contributing to global biodegradable Thus (c) is correct option.
warming.
Thus (d) is correct option. 36. The biology teacher asked her students to name
two examples of renewable energy sources.
33. Pooja is studying types of pollutants and finds Kiran said : Wind energy and Solar energy.
that radiation pollutants, unlike others, emit
Anu said : Coal and Natural gas.
harmful radiation into the environment, posing
Pooja said : Solar energy and Hydroelectric power.
serious health risks. One of the examples of
radiation pollutants is Ravi said : Petroleum and Wind energy.
(a) Sulphur dioxide Who were correct?
(b) Iodine - 131 (a) Kiran and Anu
(c) Ozone (b) Anu and Ravi
(d) Discarded fused electric bulbs
(c) Kiran and Pooja
Ans : MAIN 2019 (d) Pooja and Ravi
Iodine-131 is a radioactive pollutant that emits Ans : MAIN 2013
radiation, leading to potential health hazards,
especially when it accumulates in the human Wind, solar, and hydroelectric power are
thyroid. renewable energy sources. Coal, natural gas, and
Thus (b) is correct option. petroleum are non-renewable energy sources.
Thus (a) is correct option.
CH 14 : POLLUTION

5. The prime source of chlorofluorocarbons is: Ans : SPQ 2010

(a) Refrigeration equipments The rise in greenhouse gases traps more heat in
(b) Vehicular emissions the atmosphere, leading to global warming and
(c) Industrial effluents impacting climate patterns worldwide.
(d) Domestic sewage Thus (c) is correct option.
Ans : COMP 2020
10. The primary source of chiorofluorocarbons is
Refrigeration equipment is the main source of (a) Vehicular emissions
CFCs, which are harmful to the ozone layer when (b) Refrigeration equipments
released into the atmosphere. (c) Industrial effluents
Thus (a) is correct option. (d) Domestic sewage

6. Eutrophication leads to death of fish due to Ans : MAIN 2007

(a) Increased O2 content Refrigeration equipment is a major source of CFCs,

(b) Increased algal content which, when released, contribute significantly to
(c) Decreased algal content ozone layer depletion.
(d) Decreased O2 content Thus (b) is correct option.
Ans : MAIN 2023
11. Which one of the following is non-biodegradable?
Eutrophication increases algal growth, which, (a) Vegetable peel
upon decay, depletes oxygen in the water, leading (b) DDT
to hypoxic conditions that can result in fish (c) Cardboard
deaths. (d) Bark of trees
Thus (d) is correct option.
Ans : COMP 2009

7. International ozone day is on DDT is non-biodegradable, meaning it remains

(a) 11th July in the environment for a long time, leading to
(b) 16th August accumulation and potential harm to ecosystems.
(c) 5th June Thus (b) is correct option.
(d) 16th September
12. CFCs cause
Ans : MAIN 2013
(a) Depletion of CO2
International Ozone Day, celebrated on 16th (b) Increase of ozone layer
September, promotes awareness and action to (c) Depletion of ozone layer
protect the ozone layer. (d) Increase of CO2
Thus (d) is correct option.
Ans : COMP 2004

8. The unfavourable alteration of environment due CFCs contribute to ozone layer depletion by
to human activities is termed as breaking down ozone molecules, reducing the
(a) Pollution layer's ability to shield Earth from harmful UV
(b) Ecological disturbance radiation.
(c) Catastrophe Thus (c) is correct option.
(d) Ecological degradation
13. Which of the following is a non-biodegradable
Ans : COMP 2019
pollutant?
Pollution refers to the adverse changes in the (a) Paper
environment caused by human activities, which (b) Wood
can harm ecosystems and health. (c) Cloth
Thus (a) is correct option. (d) DDT

9. An increased rate of greenhouse gases causes Ans : MAIN 2005

(a) Depletion of ozone layer DDT is a non-biodegradable pollutant that

(b) Eutrophication remains in the environment for extended periods,
(c) Global warming causing bioaccumulation and ecological harm.
(d) Algal bloom Thus (d) is correct option.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 431

(c) A – Carbon monoxide, B – Lead. ONE MARK QUESTIONS

(d) A – Ozone, B – Plastic waste.
Ans : MAIN 2010
DIRECTION : Name the following :
Particulate matter causes smog and respiratory
issues. Heavy metals bioaccumulate, affecting the 45. The undesirable change in the environment
food chain. leading to its deterioration.
Thus (a) is the correct option.
Ans : SQP 2025
43. Rahul matched pollutants with their effects on the
Pollution
environment. He tabulated the pairs as follows:
46. Mention tux. harmful effects of noise pollution.
Pollutant Effect on the environment
Ans : MAIN 2024
A Causes acid rain, damaging plants
and soil. Damage ear drum / Nervous irritability/ Disturbs
sleep
B Reduces the oxygen level in water
bodies 47. A non-biodegradable pesticide.
Identify the correct pair of pollutants: Ans : MAIN 2013
(a) A – Sulfur dioxide, B – Oil spills.
(b) A – Nitrogen oxides, B – Organic waste. Dichloro Diphenyl Trichloroethane.
(c) A – Carbon monoxide, B – Nitrates.
48. The pollutants that cannot be broken down to
(d) A – Methane, B – Heavy metals.
simple and harmless products.
Ans : COMP 2015
Ans : COMP 2016
Nitrogen oxides cause acid rain, while organic
Non-biodegradable
waste depletes oxygen in water, harming aquatic
life. 49. The chemicals leading to the formation of ozone
Thus (c) is the correct option. hole.
44. Anjali matched pollutants with their effects on the Ans : SQP 2012
environment. She tabulated the pairs as follows:
Chlorofluorocarbons
Pollutant Effect on the environment
50. The gases which mainly contribute for causing
A Causes thinning of the ozone layer. acid rains.
B Affects Plants growth by reducing
Ans : COMP 2014
Identify the correct pair of pollutants:
(a) A – CFCs, B – Excessive fertilizers. Sulphur dioxide and nitrogen oxides
(b) A – Methane, B – Plastic waste. 51. The element which cause radiations.
(c) A – Carbon dioxide, B – Heavy metals.
(d) A – Sulfur dioxide, B – Pesticides. Ans : MAIN 2010

Ans : SQP 2015 Uranium/thorium/strontium

CFCs deplete the ozone layer. Excessive fertilizers 52. The gas that reduces O2 carrying capacity of the
reduce soil fertility, harming plant growth. blood.
Thus (a) is the correct option.
Ans : COMP 2011

Carbon monoxide

53. Increase in concentration of certain non-

biodegradable substances in higher trophic levels
of a food chain.
Ans : SQP 2018

Biomagnification
CH 14 : POLLUTION

37. A geography teacher asked her students to provide DIRECTION : Matching Type Question
two causes of soil pollution.
Rahul said : Excessive use of fertilizers and Plastic 40. Sita matched pollutants with their effects on the
waste. environment. She tabulated the pairs as follows:
Shweta said : Overgrazing and Rainwater
harvesting. Pollutant Effect on the environment
Manish said : Industrial waste and Pesticides. A Causes global warming and ice cap
Ananya said : Afforestation and Mining. melting.
Who were correct?
B Pollutes water, leading to algal
(a) Rahul and Manish
blooms.
(b) Shweta and Ananya
(c) Rahul and Shweta Identify the correct pair of pollutants:
(d) Manish and Ananya (a) A – Methane, B – Nitrates.
(b) A – Carbon monoxide, B – Pesticides.
Ans : COMP 2019
(c) A – Ozone, B – Heavy metals.
Excessive use of fertilizers, plastic waste, (d) A – Carbon dioxide, B – Phosphates.
industrial waste, and pesticides all contribute
Ans : MAIN 2012
to soil pollution. Afforestation and rainwater
harvesting are beneficial practices. Carbon dioxide contributes to global warming.
Thus (a) is correct option. Phosphates in fertilizers cause algal blooms,
depleting oxygen in water bodies.
38. A science teacher asked her students to give two Thus (d) is the correct option.
examples of greenhouse gases.
Rohit said : Carbon dioxide and Methane. 41. Neha matched pollutants with their effects on the
Sara said : Nitrogen and Oxygen. environment. She tabulated the pairs as follows:
Vikas said : Water vapor and Methane.
Pollutant Effect on the environment
Nina said : Carbon monoxide and Ozone.
Who were correct ? A Leads to hearing loss and stress in
(a) Rohit and Sara (b) Rohit and Vikas humans.
(c) Vikas and Nina (d) Sara and Nina B Pollutes water and harms marine
Ans : MAIN 2017 life.

Carbon dioxide, methane, and water vapor are Identify the correct pair of pollutants:
greenhouse gases. Nitrogen, oxygen, and carbon (a) A – Noise pollution, B – Oil spills.
monoxide are not greenhouse gases. (b) A – Particulate matter, B – Phosphates.
Thus (b) is correct option. (c) A – Lead, B – Nitrates.
(d) A – Nitrogen oxides, B – Carbon dioxide.
39. A physics teacher asked the students to give two Ans : COMP 2011
examples of non-conventional energy sources.
Kartik said : Solar energy and Wind energy. Noise pollution causes hearing loss. Oil spills
Arjun said : Coal and Biomass energy. pollute water, affecting marine organisms.
Nisha said : Wind energy and Geothermal energy. Thus (d) is the correct option.
Meera said : Natural gas and Solar energy.
42. Ravi matched pollutants with their effects on the
Who were correct?
environment. He tabulated the pairs as follows:
(a) Kartik and Meera
(b) Arjun and Nisha Pollutant Effect on the environment
(c) Kartik and Nisha
A Causes smog and respiratory issues
(d) Arjun and Meera
in humans.
Ans : SQP 2018
B Leads to bioaccumulation in aquatic
Solar, wind, and geothermal energy are non- organisms.
conventional sources of energy. Coal and natural Identify the correct pair of pollutants:
gas are conventional sources. (a) A – Particulate matter, B – Heavy metals.
Thus (c) is correct option. (b) A – Nitrogen dioxide, B – Pesticides.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 433

DIRECTION : Give the Biological/technical term for 83. Substances which degrades the quality/
the following : productivity of soil are regarded as ______
Ans : COMP 2020
76. The process causing an undesirable change in the
environment. Soil pollutants

Ans : MAIN 2016 84. DDT is a ______ type of pollutant and

Pollution undergoes ______ in successive trophic levels.
Ans : MAIN 2010
77. A constituent that causes pollution. 2013
Non-biodegradable, Bio-magnification
Ans : COMP 2019

Pollutants 85. ______ are the major aerosol pollutant present

in jet emission, cause ozone depletion.

DIRECTION : The statement given below is false. Ans : SQP 2015

Rewrite the correct form of the statement by changing Chlorofluorocarbons

the word which is underlined.
86. BOD stands for ______ and it indicates the
78. CNG is mainly responsible for the formation of degree of ______.
acid rain. Ans : MAIN 2017

Ans : SQP 2015 Biological oxygen demand, water pollution

SO2 is mainly responsible for the formation of
87. A heavy metal pollutant released in automobile
acid rain.
exhausts ______.
Ans : COMP 2019
DIRECTION : Choose the ODD one out from the
following terms given and name the CATEGORY to Lead
which the others belong :
88. Afforestation can check the advancement of
______.
79. Example : Nose, Tongue, Arm, Eye
Ans : SQP 2017
Ans : COMP 2018
Desert
Odd Term - Arm, Category - Sense organs).
89. The coal using electric power plants cause
80. Detergents, X-rays, sewage, oil spills.
______ pollution as well as ______
Ans : MAIN 2018 pollution.
Odd term - X rays. Ans : MAIN 2019

81. Sewage, Newspaper, Styrofoam, Hay. Air, thermal/water

Ans : COMP 2016 90. An undesirable change in the environment is
Styrofoam, All others are biodegradable called ______.
pollutants. Ans : COMP 2020

Pollution
DIRECTION : Fill in the blanks with suitable words
in the following sentences : 91. The pollutants that can be decomposed by
microorganisms is ______.
82. Automobiles are the largest source of______ Ans : MAIN 2009
pollution in cities.
Biodegradable
Ans : SQP 2019
92. ______ Cause depletion of ozone layer.
Air
Ans : SQP 2010
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CH 14 : POLLUTION

160. Write two effects of soil pollution. (i) Fitting anti-pollution devices.
(ii) Efficient engines should be fitted in vehicles.
Ans : COMP 2020
(iii) Use of CNG in vehicles.
Two effects of soil pollution are as follows : (iv) Use lead-free petrol.
(i) Excessive use of fertilizers and pesticides kills
bacteria present in the soil and reduces soil 167. List two measures each for controlling air pollution
fertility. and water pollution.
(ii) Acid rain decreases the fertility of soil. Ans : MAIN 2013

161. Define thermal pollution. What are its effects ? Air pollution –
(i) Pollutants from industries can be controlled
Ans : SQP 2023
by scrubbers and filters.
It is caused by the discharge of hot water into (ii) Non-polluting gases can be used in vehicles
the lakes and streams by the industries which use like CNG.
water for cooling purposes. It affects the biotic Water pollution –
life in water. The desirable forms are replaced by (i) Treatment of sewage is done before discharging
non-desirable forms are replaced by non-desirable them into water bodies.
forms such as pathogenic forms. Hot water (ii) Excessive use of fertilizers and pesticides
also affects. The reproductive capability of the should be avoided.
organisms.
168. Why the use of CFCs should be banned?
162. What are the effects of noise pollution ?
Ans : COMP 2019
Ans : MAIN 2021
CFCs rise into the atmosphere and reduction
(i) Prolonged exposure to noise above 80dB can of ozone into O2 takes place, thereby causing
damage eardrum. depletion of the ozone layer due to rapid
(ii) Noise disturbs sleep that lead to nervous production of O2. Ozone holes cannot prevent UV
disorders. rays from entering the troposphere as a result, UV
(iii) It also disturbs the birds. rays cause diseases like skin cancer and cataract.
163. Write two methods to control noise pollution. 169. What is Montreal Protocol?
Ans : COMP 2020 Ans : MAIN 2015

(i) Planting trees interrupt the path of It is an international agreement to protect

transmission. ozone layer by reducing the production of ozone
(ii) Prohibiting blowing of horns near hospitals depleting substances. This agreement has been
and schools. signed by more than 175 countries.
(iii) Using ear plugs.
170. When did Chernobyl disaster occur? How did it
164. State any two harmful effects of acid rain. happen?
Ans : MAIN 2011 Ans : SQP 2017

Acid rain is harmful to eco systems, human Chernobyl disaster took place due to the explosion
health, heritage buildings, marble statues etc. of four reactors of a nuclear power plant on 26th
April, 1986 at Chernobyl, in Ukraine, USSR. This
165. What is the purpose of using unleaded petrol?
was mainly due to leaking of nuclear radiation
Ans : COMP 2015 that caused several deaths.
When petrol contains lead it produces harmful
171. What is ozone hole? How are they produced?
gases that may cause health problems. Unleaded
How it affects the life on the earth?
petrol reduces the ill effects to a certain level.
Ans : SQP 2012
166. Suggest any two methods of controlling automobile
Ozone is an allotropic form of oxygen. It is located
pollution.
at the upper atmosphere (stratosphere). This
Ans : SQP 2012 protects the earth from harmful UV radiations.
In the stratosphere, the UV radiations transforms
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 435

DIRECTION : Complete the following: Pesticides/DDT

112. ______is an example of particulate pollutant. 122. ______ is the major pollutant of acid rain.

Ans : MANI 2021

Ans : COMP 2000

Dust SO2

113. ______are the chief cause of depletion of ozone 123. ______ a combination of fog and smoke.
layer. Ans : MAIN 2001

Ans : COMP 2023 Smog

CFCs 124. Ozone intercept ______ radiation.
114. Hot water is given out from ______ power Ans : SQP 2005
plant.
UV
Ans : SQP 2021
125. Ozone is found at ______ of the atmosphere.
Thermal
Ans : MAIN 2007
115. A decibel value more than ______ decibel
Stratosphere
causes noise pollution.
Ans : MAIN 2000
126. Excessive nourishment leading to the loss of
aquatic life is ______.
80
Ans : COMP 2010
116. Noise pollution is measured in ______.
Eutrophication
Ans : SQP 2001
127. Greenhouse effect leads to______.
Decibels
Ans : MAIN 2015
117. The type of pollution which affects respiratory
Global warming
tract is ______.
Ans : COMP 2005
DIRECTION : Mention one difference between:
Air pollution
128. Primary and Secondary pollutants.
118. The pollutants which can be decomposed by
micro-organisms is ______. Ans : COMP 2016

Ans : MAIN 2007 Primary pollutants remain in the environment, in

the form to which they are released. Secondary
Biodegradable
pollutants are formed by the reaction between
119. ______ is an air pollutant which affects two primary pollutant or with the environmental
visibility. factors.

Ans : COMP 2011 129. Biodegradable and non-biodegradable pollutants.

Smog Ans : SQP 2018

120. Inhalation of ______ lowers the O2 carrying Biodegradable pollutants are organic in nature
capacity of haemoglobin. and decompose by bacteria and fungi. Non-
biodegradable pollutants are inorganic and not
Ans : MAIN 2013
decompose by biological agents.
CO

121. ______ is a threat to life both on land and in DIRECTION : Define the following :
water. 130. Biomedical wastes.
Ans : SQP 2019
Ans : MAIN 2019
CH 14 : POLLUTION

CFCs False. Automobiles fuel are the main source of air

pollution.
93. A combination of smoke and fog is______.
104. 16th September is the International ozone day.
Ans : COMP 2015

Smogv Ans : SQP 2011

True.
94. Noise is measured in______.
105. CO2 reduces the O2 carrying capacity of
Ans : MAIN 2017
hemoglobin.
Decibel
Ans : MAIN 2015

True.
DIRECTION : Write “True” or “False”.
106. Eutrophication in lakes is due to pesticides.
95. Man is the only source of environment pollution.
Ans : COMP 2019
Ans : COMP 2019
False. Eutrophication in lakes is due to fertilizers.
False

96. All pollutants are degradable. DIRECTION : Choose the correct option from the
brackets:
Ans : MAIN 2018

False 107. International ozone day is on

[11th July, 16th September, 5th June, 16th August]
97. All types of wastelands can be reclaimed.
Ans : SQP 2018
Ans : SQP 2011
16th September.
True
108. Which among the following diseases is caused by
98. All types of pollutants can be recycled. water pollution?
Ans : MAIN 2015 [Measles, tuberculosis, typhoid, haemophilia]

False Ans : MAIN 2015

Typhoid.
99. Kolkata is the most polluted city in India.
Ans : COMP 2019 109. The prime source of chlorofluorocarbons is:
[Vehicular emissions, Industrial effluents,
True Domestic sewage, Refrigeration equipments]
100. Underground water is safest and not polluted. Ans : COMP 2019

Ans : SQP 2011 Refrigeration equipments

False 110. Which among the following is the main cause of
101. DDT is a non-degradable pollutant. ozone depletion?
[Sulphur dioxide, carbon dioxide, CFCs, nitrogen
Ans : COMP 2015 dioxide]
True Ans : COMP 2019

102. Any unwanted sound is called noise. CFCs.

Ans : MAIN 2017 111. An increased rate of greenhouse gases causes
True. [Depletion of ozone layer, global warming,
eutrophication, algal bloom]
103. Insecticides are the main source of air pollution.
Ans : MANI 2020
Ans : COMP 2019
Global warming.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 437

These are not natural but added to the 155. State two hanuftd effects of acid rain on the
environment by the activity of man. environment.

148. Define contamination. Ans : MAIN 2024

Ans : COMP 2010

Harmful effects of acid rain :
(i) It corrodes buildings and metal structures.
Contamination is the presence of harmful (ii) It can also affect human health by causing
organisms or their products causing disease or respiratory diseases like asthma.
discomfort. (iii) It leads to the acidification of lakes and rivers,
which harms aquatic life.
149. Define quantitative pollutants.
Ans : SQP 2015 156. State any two harmful effects of acid rain.
Ingredients whose concentration reach beyond Ans : SQP 2013
a threshold value in the environment become Damage to vegetation/decay of building materials
pollutants, e.g., CO, CO2, nitrogen oxides. and paints/erosion of ancient monuments, statues
and sculptures/degrades visibility and harms
150. What constitutes smog ?
human health/marine life harmed due to increased
Ans : SQP 2015 acidity of water.
Smog is dark or opaque fog which is formed by the
157. Explain the term greenhouse effect
dust and smoke articles causing condensation of
water vapours around them as well as attracting Ans : COMP 2015
chemicals like SO2, H2S, NO2 etc. A naturally occurring process that aids in heating
the Earth’s surface and atmosphere. Certain
151. What would happen if CO2 concentration of the
atmospheric gases like CO2, water vapour and
atmosphere increases ?
methane are able to change the energy balance
Ans : MAIN 2016 of the planet by absorbing long wave radiation
It leads to greenhouse effect. emitted from Earth’s surface. Without greenhouse
effect life on this planet would probably not exists.
152. What are the sources of noise pollution ?
158. Match the items given in column A and B.
Ans : COMP 2018

Loud speakers, jet planes, musical bands in public Column A Column B

places, etc. (a) Earmuffs (i) Particulate matter
(b) Aerosol (ii) High noise level
(c) Landfills (iii) Chlorofluorocarbon
TWO MARKS QUESTIONS (d) Electrostatic (iv) CO and NO
precipitators
153. State two objectives of Swachh Bharat Abhiyan. (e) Catalytic (v) Solid wastes
converter
Ans : SQP 2025

To clean streets, roads, cities and towns To Ans : SQP 2017

eliminate open defecation by constructing toilets. (a)-(ii), (b)-(iii), (c)-(v), (d)-(i), (e)-(iv)
Management of solid and liquid waste.
159. Define BOD. What is its use ?
154. Carbon monoxide is dangerous when inhaled in
excess. Comment on the statement. Ans : MAIN 2019

Biological oxygen demand is the amount of oxygen

Ans : MAIN 2024
required by phytoplanktons of polluted water to
Carbon monoxide easily combines with complete the decomposition of organic matter
haemoglobin to form Carboxyhemoglobin, which present in one litre of water. The value of BOD
cuts off supply of oxygen to tissues. indicates the degree of water pollution. Higher its
value, the more is the degree of water polluted.
CH 14 : POLLUTION

Swach Bharat is evaluated on regular basis. (i) What is water pollution?

People from different sections of the society have (ii) Write two effects of it.
come forward and join this mass movement of (iii) What are the sources of it?
cleanliness. The municipal corporation needs to
Ans : COMP 2019
improve the system of garbage disposal for better
and hygienic cities towns in India. (i) Addition of harmful pollutants into water
bodies that may adversely affect the aquatic
178. The given figure shows air pollution. Study the life is water pollution.
figure and answer the following questions. (ii) (a) It causes many diseases.
(b) Oil spills cause reduction in O2 supply to
aquatic organisms.
(iii) (a) Domestic wastes
(b) Industrial wastes
(c) Agricultural wastes

FIVE MARKS QUESTIONS

180. Given below is a representation of a kind of

pollution. Study the same and answer the
questions that follow :
(i) Write the sources of air pollution.
(ii) What are the effects of it? Give three points.
(iii) How would you control it?
Ans : MAIN 2015

(i) Vehicles and Industries.

(ii) (a) It damages the respiratory tract of
human.
(b) Hydro-carbons cause cancer.
(c) It also reduces crop yield.
(iii) (a) Particulate pollutants should be
controlled by scrubbers.
(b) Remove sulphur from fuel before use. (i) Name the kind of pollution.
(ii) List any three common sources of this
179. Riya notices that waste from factories and homes pollution.
flows untreated into the nearby river, leading to (iii) Mention three harmful effects of this pollution
pollution. This has affected aquatic life and the on human health.
local community relying on the river. (iv) Explain the term ‘Pollutant’.
(v) Name two soil pollutants.
Ans : COMP 2017

(i) Noise pollution.

(ii) Automobiles and road transport, jet
aeroplanes, loudspeakers, radio and musical
bands.
(iii) Nervous irritability, damage of eardrum,
disturbs piece of mind.
(iv) The agents that cause pollution is called
Pollutant.
(v) Pesticides, Styrofoam, Chemical fertilizers,
domestic and industrial wastes.
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 439

O2 to O3. The oxygen molecule is broken down 175. Soil pollution occurs due to chemical fertilizers,
by solar radiation into free oxygen atoms. These pesticides, and industrial waste. It reduces soil
then reacts with oxygen molecules to form ozone. fertility and contaminates groundwater, affecting
Ozone hole is the thinning of ozone layer by some agriculture and human health.
air pollutants like CFC, that react with oxygen (i) What causes soil pollution?
to form CO2 and generate heat in the atmosphere (ii) How does soil pollution affect agriculture?
resulting in global warming. Depletion of ozone
Ans :
layer causes skin cancer, cataract etc.
(i) Chemical fertilizers, pesticides, and industrial
172. Study the given figure and answer the following waste.
questions : (ii) It reduces soil fertility.

THREE MARKS QUESTIONS

176. Study the picture given below and answer the

questions:

(i) What does the figure depict ?

(ii) Write three sources of the figure.
Ans : COMP 2021

(i) Noise pollution

(ii) (a) Loud speaker
(b) Radio (i) How does water get polluted?
(c) Horns of automobiles. (ii) What is the effect of water pollution on
173. What is sewage? What is the effect of discharging human life?
untreated sewage into the river? (iii) Mention one control measure to stop the
pollution of water bodies.
Ans : SQP 2014
Ans : SQP 2025
Sewage is the liquid wastes from the household
activities, such as kitchen wastes. Untreated (i) Sewage, industrial effluents, oil spills
sewage disposed into the river may reduce the (ii) Spread of diseases like diarrhea, cholera,
amount of oxygen content in the river due to algal typhoid.
bloom. (iii) Sewage must be treated before letting it into
water bodies.
174. How does sewage treatment plants reduces
pollution? 177. Write briefly about Swach Bharat Abhyian.

Ans : MAIN 2015

Ans : MAIN 2019

Sewage treatment removes the harmful substances Swach Bharat Abhiyan (A national campaign for
and the treated water can be used for various clean India) is a campaign initiated by government
purposes like in agriculture as it contains many of India that aims to clean up the streets, roads
minerals like potassium, nitrogen, phosphorus, and infrastructure of India’s cities, small towns
etc. in it. and rural areas. It also aims to eliminate open
defecation the performance of each city towards
CH 14 : POLLUTION

Biomedical wastes are generated from the warming up of the earth.

hospitals clinics and nursing homes. These when
disposed in the soil, deteriorate the soil quality. It 138. Noise pollution
may kill the soil organisms. These include needle, Ans : SQP 2015
syringe, unused tablets, dressings etc.
Unwanted sound that may cause harm to the
131. Acid rain living organisms is noise pollution.

Ans : COMP 2020 139. Ozone hole

Burning of fossil fuels like coal produces SO2. It Ans : MAIN 2019
combines with water in the atmosphere and forms
Release of some chemicals like CFCs from
sulphuric acid that falls as acid rain. It pollutes
refrigerators as chlorine radicals break ozone to
rivers and damages buildings and monuments.
release oxygen and thus make the layer of ozone
132. Thermal pollution thinner. This is called ozone hole.

Ans : SQP 2022

DIRECTION : Answer the following :
The hot water released from the thermal power
plant into water bodies causes thermal pollution.
140. Give examples of two gaseous pollutants.
It affects the life of aquatic organisms.
Ans : SQP 2012
133. Eutrophication
CO2, SO2
Ans : MAIN 2020
141. What are the sources of water pollution ?
Excessive nourishment due to discharge of sewage
into static water leads to the loss of aquatic life. Ans : COMP 2013
The organic matter increases growth of algae that Sewage, agricultural wastes.
consumes a lot of O2 content for respiration. This
decreases the O2 level and causes problem for 142. What is the effect of inhalation of CO ?
aquatic organisms.
Ans : MAIN 2015

134. Biomagnification It reduces the O2 carrying capacity of haemoglobin.

Ans : COMP 2000
143. What are the sources of radiation ?
High concentration of toxic substances like DDT
Ans : COMP 2019
in the various levels of food chains.
X-rays, nuclear explosives.
135. Non-biodegradable pollutants.
144. Name the unit to measure noise pollution.
Ans : SQP 2001
Ans : MAIN 2020
The pollutants that are not decomposed by micro-
organisms e.g. DDT, plastic, etc. Decibles (dB).

136. Global warming. 145. Define oil spill.

Ans : MAIN 2005 Ans : COMP 2005

Increasing concentration of CO2 in the atmosphere It is the leakage of oil on the surface of sea water
due to burning of fossil fuels causes heating of the during transport and unloading of oil tanker.
earth’s surface that may cause melting of glaciers.
146. In which zone of atmosphere, ozone layer is
137. Greenhouse effect. present?

Ans : COMP 2010 Ans : SQP 2007

Burning of fossil fuels produces CO2 that is used by Stratosphere.

plants for photosynthesis. Excessive accumulation
147. What are Qualitative pollutants ?
of CO2 near the earth’s surface traps the heat and
prevents the escape of heat. This results in the Ans : MAIN 2006
ICSE CHAPTERWISE PYQ CLASS 10 BIOLOGY PAGE 441

181. Given below is a representation of a type of (i) Name the kind of pollution.
pollution. (ii) List any three common sources of this
pollution.
(iii) Mention three harmful effects of this pollution
on human health.
(iv) Explain the term ‘Pollutant’.
(v) Name two soil pollutants.
Ans : MAIN 2021

(i) Noise pollution.

(ii) The sources of noise pollution are loud
speakers, horns of automobiles, jet engines
etc.
(iii) (a) Prolonged exposure to noise above 80 db
can damage eardrum.
(b) Disturbs sleep thereby leads to nervous
disorders.
Study the picture and answer the questions : (c) It interfers communication.
(i) Name the type of pollution shown in the (iv) Pollutants are the unwanted substances
picture. introduced into the environment which
(ii) Name one source of this pollution. adversely affect the environment.
(iii) How does this pollution affect human health? (v) Soil pollutants are fertilisers, pesticides, lead
(iv) Write one measure to reduce this pollution. biomedical wastes etc.
(v) State one gaseous compound that leads to
the depletion of the ozone layer and creates
‘Ozone holes’.
Ans : SQP 2018
CASE BASED QUESTION
(i) Air pollution.
(ii) Smoke from vehicles/harmful gases from 183. Air pollution results from vehicle exhaust and
industries. industrial emissions, causing respiratory problems
(iii) SO2 causes bronchitis, Lead causes blood cell like asthma and bronchitis. It also contributes
shortage, Smog leads to asthma and poor to environmental issues like acid rain and global
visibility, Oxides of nitrogen decreases oxygen warming.
carrying capacity of blood. (i) What are the main causes of air pollution?
(iv) Use of lead free petrol and CNG. (ii) How does air pollution affect human health?
(v) Chloroflourocarbon. (iii) What environmental issues are caused by air
pollution?
182. Given below is a representation of a kind of (iv) How can air pollution be controlled?
pollution. Study the same and answer the
questions that follow: Ans :
(i) Vehicle exhaust and industrial emissions.
(ii) It causes respiratory issues like asthma.
(iii) Acid rain and global warming.
(iv) By using filters and planting trees.

184. Water pollution occurs when pollutants like

sewage, industrial waste, and chemicals enter
water bodies. It harms aquatic life and makes
water unsafe for drinking and other uses.
(i) What are the sources of water pollution?
(ii) How does water pollution affect aquatic life?
(iii) What diseases are caused by polluted water?
(iv) How can water pollution be reduced?
CH 14 : POLLUTION
Ans :
(i) Sewage, industrial waste, and chemicals.
(ii) It depletes oxygen, killing aquatic organisms.
(iii) Cholera and typhoid.
(iv) By recycling waste and treating sewage.

185. Ravi lives close to a busy road and near a factory

area. He constantly hears loud noises from vehicles,
machines, and construction work, which affects
his sleep and concentration. Recently, Ravi has
noticed that his neighbors are also facing similar
issues due to the continuous noise in the area.

(i) Name the kind of pollution.

(ii) List any three common sources of this
pollution.
(iii) Mention three harmful effects of this pollution
on human health.
(iv) Explain the term ‘Pollutant’.
(v) Name two soil pollutants.
Ans :
(i) Noise pollution.
(ii) The sources of noise pollution are loudspeakers,
vehicle horns, and construction activities.
(iii) Prolonged exposure to loud noise can
damage the eardrum. Disturbs sleep and
leads to nervous disorders. Interferes with
communication.
(iv) Pollutants are unwanted substances
introduced into the environment that
adversely affect it.
(v) Soil pollutants include fertilizers, pesticides,
and lead.

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