IMPORTANT BIOLOGY QUESTIONS (BOARD AND SAMPLE PAPERS)

Sexual Reproduction in flowering plants

1. The part of the ovule that develops into protective coats of a seed after
fertilization in a typical flowering plant is :
(A) embryo sac (B) nucellus (C) integuments (D) megaspore
2. In which one of the following floral plants are many embryos formed in
the seeds without fertilisation of the egg cell ?
(A) Black pepper (B) Mustard (C) Groundnut (D) Citrus
3. Assertion (A) : The zygote gives rise to heart-shaped embryo and subsequently proembryo
in most angiosperms.
Reason (R) : The zygote is present at the micropylar end of the embryo
4. The ploidy of the apomictic embryos developing from the integument cells
and synergids respectively would be :
(A) n, 2n (B) 2n, n (C) 3n, 2n (D) 2n, 3n
5. The mechanism to produce seeds without fertilisation has evolved in the
given family of the flowering plants :
(A) Asteraceae (B) Solanaceae (C) Malvaceae (D) Liliaceae
6. Embryo formation without fertilization is observed in some species of :
(A) Maize (B) Rose (C) Mango (D) Rice
7. The ploidy of apomictic embryos developing from the nucellus and
antipodal cells respectively would be :
(A) 2n, 3n (B) 2n, n (C) 3n, 2n (D) n, 2n
8. Which of the following seeds have remained alive for the longest period ?
(a) Phoenix dactylifera (b) Striga asiatica (c) Mangifera indica (d) Yucca gigantea
9. Match the correct Structures given in Column I with the Fruit in Column II in the chart
given below :
Column I Column II
(Structure) (Fruit)
P. Perisperm i. Maize
Q. Thalamus ii. Black pepper
R. Pericarp iii. Strawberry
 S. Endosperm iv. Mango
(a) P-i, Q-ii, R-iii, S-ii (b) P-ii, Q-iii, R-iv, S-i
(c) P-iii, Q-i, R-i, S-iii (d) P-iv, Q-i, R-ii, S-iv
10. Remnants of nucellus are persistent during seed development in:
a) pea
b) groundnut
c) wheat
d) black pepper
11. The wall layer of microsporangium which nourishes the pollen grain is:
a) epidermis
b) endothecium
c) middle layers
d) tapetum

12. Assertion: Primary endosperm nucleus is diploid.

Reason: It is the product of double fertilisation.
Questions:

1) Draw a T.S. of a mature anther of an angiosperm. Label its any three

wall layers and mention their functions. 2

2) (a) Explain the process of the development of a male gametophyte in an angiosperm.

(b) Why is it called a male gametophyte? [2]

3)

4) Explain any four devices that flowering plants have developed to encourage cross-
pollination.
(ii) Why do plants discourage self-pollination ? State any one reason. 5
5)

6) (a)(i) Describe the arrangement of nuclei and cells in a mature embryo sac of a typical
angiosperm.
(ii) Explain the devices the flowering plants have developed to prevent the following types of
pollination:
(1) Prevents both autogamy and geitonogamy
(2) Prevents autogamy, but not geitonogamy [5]

CBQ
1) a) The products of mitotic division of the cell formed after reduction division in
microsporophyll in angiosperms has two different fates. Justify.
b) How many mitotic divisions are required in females to form 350 seeds 3
Human reproduction
1. Which of the following options correctly matches the name of the hormone to its site of
production in the human body ?
Name of the Hormone Site of Production
P. Oxytocin i. Placenta
Q. Relaxin ii. Corpus Luteum
R. hCG iii. Pituitary Gland
S. Progesterone iv. Ovaries
(a) P-i, Q-iii, R-ii, S-iv (b) P-i, Q-iv, R-iii, S-ii
(c) P-iii, Q-iv, R-i, S-ii (d) P-ii, Q-iii, R-i, S-iv
2. Which of the following hormones are active during the ovulatory phase of menstrual cycle
in a normal human female ?
(a) FSH and LH (b) LH and Estrogen (c) FSH and Estrogen (d) Estrogen and
Progesterone
3. Assertion (A) : Breast-feeding is advised by the doctor as it is essential for the new borns.
Reason (R) : Colostrum secreted by the mother during initial days of lactation has abundant
antibodies containing IgE and IgG.
4. Observe the following line diagram depicting the 28 days menstrual cycle of a healthy
young woman.

Select the option of days on which this woman would be most and least fertile.

Questions:
1. Explain the process of hormonal regulation of spermatogenesis. 2
2. Differentiate between spermatogenesis and oogenesis in humans on the
basis of the following : 3
(a) When the process is initiated.
(b) Number of functional gametes produced per primary
spermatocyte/oocyte.
(c) Specific site at which meiosis II is completed.
3. (a) Draw a diagram of a human sperm. Label the following parts in it :
(i) Which helps in the motility of the sperm
(ii) Which helps in penetrating through the corona radiata and
zona pellucida
(iii) Which enters into the cytoplasm of the human egg
(b) Mention how is polyspermy prevented during the course of
fertilization in humans. 3
4. The figure given below shows 3 sperms A, B and C.

a) Which one of the three sperms will gain entry into the ovum?
b) Describe the associated changes induced by it on P and Q. 3

5. Trace the journey of a zygote from the isthmus of the fallopian tube up to its implantation
in the uterus of a human female. Highlight the changes the zygote undergoes during the
course of its journey up to implantation. 3

6.
 7. Explain the ovarian and uterine events taking place along with the role of pituitary and
ovarian hormones, during menstrual cycle in a normal human female under the following
phases: 5
(i) Follicular phase/proliferative phase
(ii) Luteal phase/secretory phase
(iii) Menstrual phase

8.

9.(i) Write the specific location of the following in the testis in humans:
(a) Sertoli cells (b) Leydig cells
(ii) Explain the coordination between Gonadotropins, Leydig cells and Sertoli cells and their
role in spermatogenesis. 5
10. Explain the phases in embryonic development from the morula stage till the establishment of
pregnancy in a human female. 5
CBQ
1. Given below is a diagrammatic sectional
view of a seminiferous tubule. [3]
State the developmental process of:
(a) (i) b' from 'a'.
(ii) 'e' from 'd'.
(iii), 'd' from 'b'.
(b) Identify 'a', 'b' and 'c'.

2. Study the diagram and answer the questions:

a) What does the diagram given below signify?

b) What led to the events depicted beyond X in the diagram?

3. Study the graph and answer the questions

a. Which hormonal levels are discussed? How does it get initiated?

b. Give the significance of rise in the levels as represented by EF.
Reproductive health
1. A human male decides to adopt a surgical method for contraception.
Identify the point in the diagram where a cut would be made and tied.

(a) Point S (b) Point R(c) Point Q (d) Point P

Questions:
1.

2
2. State the procedure followed in the technique of amniocentesis. List any
two advantages of this technique. 2
3. Explain the IUI and IUT methods of assisted reproductive technologies. 3
4. Expand and explain the following techniques used in the Test Tube Baby' programme:
(a) GIFT
(b) ZIFT
(c) IUI 3
5. Placed below are case studies of some couples who were not able to have kids. These
couples are not ready for adoption or taking gametes from donors. After thoroughly
examining the cases, which Assisted Reproductive Technology will you suggest to these
couples as a medical expert? Explain briefly with justification of each case. 5

6. Given below are certain situations. Analyse the situation and suggest the name of suitable
contraceptive device along with mode of action. 5

CBQ
1) The Medical Termination of Pregnancy (Amendment) Act, 2017 dictates that a pregnancy
may be terminated on certain considered grounds within the first 12 weeks of pregnancy on
the opinion of one registered medical practitioner. If the pregnancy has lasted more than 12
weeks, but fewer than 24 weeks, two registered medical practitioners must be of the opinion,
formed in good faith, that the required ground exist.
[Note: Grounds refer to circumstances or conditions.]
Describe two grounds under which medical termination of pregnancy is permitted.
Principles of inheritance and variation
1. A Snapdragon plant bearing pink colour flowers is crossed with a Snapdragon plant
bearing white colour flowers. The expected phenotypic percentage of the offspring is :
(A) 50% Red : 50% White
(B) 25% Red : 50% Pink : 25% White
(C) 50% Pink : 50% White
(D) 25% Pink : 50% Red : 25% White
2.

3. Choose the set of sex determining chromosomes that indicates the correct sex of the
respective organism.
(a) Homozygous sex chromosomes (ZZ) determine female sex in birds
(b) XO type of sex chromosomes determine male sex in grasshoppers
(c) XXY condition in humans, as found in Turner Syndrome, determines male sex
(d) Homozygous sex chromosomes (XX) produce male sex in Drosophila.
4. Assertion (A) : In humans the genotype with all the dominant alleles (AABBCC) will have
the darkest skin colour.
Reason (R) : In a polygenic trait, phenotype reflects the contribution of each allele.
5. Which of the following statements are true about the males in a colony of honey bees ?
(i) They have 16 chromosomes per cell.
(ii) They produce sperms by meiosis.
(iii) They have a grandfather but no father.
(iv) All males in the colony are haploid except one.
(a) (i) and (iii) only (b) (ii) and (iii) only (c) (iii) and (iv) only (d) (ii) and (iv) only
6. Assertion (A) : In a monohybrid cross between tall plants and dwarf plants, the F2
generation showed tall and dwarf plants in the ratio of 3 : 1.
Reason (R) : There is no blending of traits/characters in the F2 generation.
7. In a certain species of insects, some have 13 chromosomes, and the others have
14chromosomes.The 13 and 14 chromosome bearing organisms are
a) males and females, respectively
b) females and males, respectively
c) all males
d) all females
8. At a particular locus, the frequency of allele A is 0.8 and that of allele a is 0.2.
What would be the frequency of heterozygotes in a random mating population at
equilibrium?
a) 0.32
b) 0.16
c) 0.24
d) 0.48

9. What should be the genotype of the indicated member?

a) AA
b) Aa
c) XY
d) aa
Questions:

1.

2.
3

3. A homozygous tall pea plant with green seeds is crossed with a homozygous dwarf pea
plant with yellow seeds.
(i) Write the possible phenotype and genotype of F₁ generation.
(ii) State the laws of Mendel that are proved true by the F₁ generation.
(iii) Mention the F₂ phenotypic ratio along with their possible phenotypes.
(iv) Write the genotypes of the male and female gametes produced by F₁ progeny. [5]
4.

CBQ
1) A pregnant human female was advised to undergo MTP. It was diagnosed that the fetus she
was carrying had developed from a zygote having 45 chromosomes with only one X
chromosome.
a) What is this condition called and how does it arise?
b) Why was she advised to undergo MTP? 3
2) You are given a tall pea plant with green seeds. The genotype of this plant is unknown.
You are allowed to do only 'selfing' of these plants to find out the genotype of the given plant.
Work out all possible crosses and show how you would determine the genotype of the given
plant. 5
3) In shorthorn cattle, the coat colours red or white are controlled by a single pair of alleles. A
calf which receives the allele for red coat from its mother and the allele for white coat from
its father is called a 'roan'. It has an equal number of red and white hairs in its coat.
a) Is this an example of codominance or of incomplete dominance?
b) Give a reason for your answer.
c) With the help of genetic cross explain what will be the consequent phenotype of the calf
when
i. red is dominant over white ii. red is incompletely dominant. 5
Molecular Basis of inheritance

1. A DNA fragment has 2000 nucleotides, out of which 140 are Adenine. How many bases
does this DNA segment possess that have triple hydrogen bonds between them ?
(A) 280 (B) 860 (C) 1720 (D) 1860

2. In an experiment, E. coli is grown in a medium containing 14NH4Cl. (14N is the light

isotope of Nitrogen) followed by growing it for six generations in a medium having heavy
isotope of nitrogen (15N). After six generations, their DNA was extracted and subjected to
CsCl density gradient centrifugation. Identify the correct density (Light/Hybrid/Heavy) and
ratio of the bands of DNA in CsCl density gradient centrifugation.
(A) Hybrid : Heavy, 1 : 16 (B) Light : Heavy, 1 : 31
(C) Hybrid : Heavy, 1 : 31 (D) Light : Heavy, 1 : 05

3. Assertion (A) : Primary transcripts in eukaryotes are subjected to splicing to remove the
introns.
Reason (R) : Primary transcripts contain both exons and introns and the introns are non-
functional in eukaryotes.

4. A DNA fragment has 3000 nucleotides, out of which 160 are Guanine. How many bases
having double hydrogen bonds between them does this DNA fragment possess ?
(A) 160 (B) 320 (C) 1340 (D) 2680
5. Given below is a list of steps Meselson and Stahl carried out in their experiment to prove
that DNA replication is semi-conservative. Select the option that gives the correct sequence
of steps followed by them.
(i) Bacteria transferred to a N14 medium and sampled every 20 minutes.
(ii) All bacteria contain hybrid DNA (N14 DNA and N15 DNA).
(iii) Bacteria grown in N15 medium for many generations.
(iv) All bacteria contain N15 DNA.
(v) Bacteria contain either all N14 DNA or all hybrid DNA.

6. DNA profiles of the child and three individuals 1, 2 and 3 who claim to be the parents of
the child are given below. Select the option that shows the correct actual parent/parents of the
child.

(a) Individual 1 and 3

(b) Individual 1 and 2
(c) Individual 2 and 3
(d) Individual 1 is the only parent of the child amongst 1, 2 and 3
7. Identify the element used by Hershey and Chase to label the protein in their experiment,
from the following options :
(a) P32 (b) S32 (c) S35 (d) P35
8. Assertion (A) : The Covid-19 virus has a shorter life-span and evolves into new strains at a
fast speed.
Reason (R) : RNA being unstable, mutates at a faster rate.
9. Assertion (A) : For DNA sequencing, the total DNA from a cell is isolated and converted
into random fragments of relatively smaller sizes.
Reason (R) : Human genome is said to have approximately 3 × 10 9 bp and the total estimated
cost for sequencing is very high.
10. A short piece of DNA, having 20 base pairs, was analyzed to find the number of
nucleotide bases in each of the polynucleotide strands. Some of the results are
shown in the table.
 How many nucleotides containing Adenine were present in strand 2?
a) 2 b) 4 c) 5 d) 7

11. What is the smallest part of a DNA molecule that can be changed by a point
mutation?
a) Oligonucleotide b) Codon c) Gene d) Nucleotide

12. Assertion: Ribosomal RNA is synthesized in the nucleus of the cell.

Reason: It is translated with the enzyme RNA polymerase III.

Questions:

1.

2
1. (a) (i) How many types of RNA polymerases are there in a eukaryote cell? Mention which
one of them transcribes hnRNA.
(ii) Write the changes that hnRNA undergoes before it leaves the nucleus as mRNA.
[3]
OR
(b) The length of DNA in any cell is far greater than the dimension of its nucleus.
Explain how this enormous DNA is packaged in a eukaryotic cell. [3]

2. Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA
and r-RNA. Explain the role of each of them during the process of protein synthesis in
prokaryotes. [5]

3. (a) (i) Draw a labelled diagram of a replication fork in a prokaryote indicating the process
of DNA replication.
(ii) Differentiate between the two newly synthesised DNA strands within the fork.
(iii) Name the enzymes involved in the process of DNA replication.
(iv) Name the eukaryote where the semi-conservative mode of replication was
experimentally proved. 5
5. Given below is a stretch of DNA showing the coding strand of a structural gene of a
transcription unit ? 5
5’--ATG ACC GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TAA—3’

a) Write the corresponding template strand and the mRNA strand that will be transcribed,
along with its polarity.
b) If GUA of the transcribed mRNA is an intron, depict the sequence involved in the
formation of mRNA /the mature processed hnRNA strand.
i. In a bacterium
ii. In humans
c) Upon translation, how many amino acids will the resulting polypeptide have? Justify.

CBQ
1.

2. The diagram below shows the sequence of amino acids in part of a

haemoglobin molecule. 2

a) If the base T* was substituted with A, how would it affect the haemoglobin chain?
b) Name the condition and the effects associated with the above substitution.
Evolution
1. Identify the option that gives the correct type of evolution exhibited by the two animals
shown, living in the same habitat in Australia.

Mouse Marsupial mouse

(a) Convergent Evolution
(b) Disruptive Selection
(c) Divergent Evolution
(d) Homologous Ancestry

2. During the 1850s in the pre-industrialisation era in England, the

expected effect of natural selection on the number of dark-winged moths
as compared to white-winged moths was :
(A) more in number (B) less in number
(C) both were equal in number (D) both were less in number

3. S.L. Miller in 1953, to support the theory of chemical evolution, created

conditions in the closed flask that included :
(A) CH3, O2, NH3, H2O vapour at 1800 C
(B) CH4, H2, NH3, H2O vapour at 800 C
(C) CH4, CO2, H2, H2O vapour at 1800 C
(D) CH4, NH4, SO2, H2O vapour at 800 C
4. Louis Pasteur dismissed the theory of spontaneous generation by his
experiments using pre-sterilised flasks and :
(A) Live yeast (B) Killed yeast
(C) Live bacteria (D) Killed bacteria
5. The origin of life according to the early Greek philosophers was transfer
of unit of life from outer space to the different planets in the form of :
(A) seeds (B) spores
(C) gemmules (D) gametes
6. Assertion (A) : The number of white winged moths decreased drastically
after industrialisation in England.
Reason (R) : Effects of industrialisation were more marked in rural areas of England.
7. Assertion (A) : Homo sapiens have evolved from chimpanzee-like ancestors.
Reason (R) : There is no difference between the two in the amino acid sequence of the protein
Cytochrome-C.
8. Which one of the following was not present during the Mesozoic Era of
the geological time scale ?
(a) Ferns (b) Horsetails
(c) Ginkgos (d) Bryophytes
9. Variations caused due to mutations are
a) random and directionless
b) random and directional
c) random and small
d) random, small and directional

Questions:
1.(a) Darwin's theory of Natural Selection is widely accepted but some limitations have been
identified by modern biologists. Mention the limitations identified.
(b) Name and state the most accepted theory of evolution in modern times.
(c) Mention any two ways the limitations identified in Darwin's theory of evolution are
explained in modern biology. [3]
CBQ

1) The graphs below show three types of natural selection. The shaded areas marked with
arrows show the individuals in the population which are not selected. The dotted vertical
lines show the statistical means.
a) What names are given to the types of selection shown in graphs A, B and C.
b) After the selection has operated for several generations in the above populations indicated
as Graph A, B and C, graphically illustrate the probable results. 3
Microbes in human welfare

1.

2. Which one of the following fixes the atmospheric nitrogen but is not an
autotroph ?
(a) Oscillatoria (b) Rhizobium
(c) Anabaena (d) Nostoc
Questions

1. (a) Write the first step the primary effluent undergoes when it enters the secondary treatment plant and
state the purpose.
(b) What is the level of B.O.D indicative of in the secondary treatment plant? Mention its significance. [2]

2. Explain the role of microorganisms in the following:

(a) Reducing the sugar content in grape juice
(b) Production of a fuel [2]

3. (a) Name the two institutes which developed the technology of biogas production in India.
(b) Explain the main principle used in this technology. [2]

4. Name the bioactive molecule and its microbial source generally

used by physicians to treat the patients for : 3
(i) Myocardial infarction
(ii) High blood cholesterol level
(iii) Organ transplantation

CBQ
1) The aeration tank of a sewage treatment plant is not functioning properly. Explain in detail
the impact of this on the treatment of sewage and BOD of the effluent. 3