Cell The Unit of Life
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• Endomembrane system
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Cell: The Unit of Life 29
CELL: BASIC UNIT OF ORGANISMS LP LEARNING PLUS
The smallest and basic unit that is responsible for all the metabolic activities and life Learning Plus illustrate-Outside
processes of an organism is called cell. Since all organisms are made up of cells, cell is the NCERT concepts to enhance your
structural and functional unit of life of all living organisms. understanding
Based on the number of cells, organisms can be unicellular (composed of a single cell) and
multicellular (composed of multiple cells). LP
Unicellular organisms are capable of: The branch of science that deals with
the study of structure and function of
1. Independent existence a cell is called cytology.
2. Performing the essential functions of life
HISTORICAL BACKGROUND OF CELL LP
Cell was discovered by Robert Hooke. Discovery of cell
Anton Von Leeuwenhoek first saw and described a live cell. Robert Hooke examined thin slices
of cork and coined the term “Cellula”
Robert Brown discovered the nucleus for honey comb - like structure of
Cell is quite small and complex. So the complete and clear view of all its components is bottle cork (Greek cellulae = Hollow
revealed after the invention of electron microscopes. space) which later modified to cell.
He published his findings in his book
CELL THEORY ‘Micrographia’.
Cell theory was formulated by Schleiden (1838) and Schwann (1839).
Matthias Schleiden (German Botanist): He examined a large number of plants and observed
that all plants are composed of different kinds of cells which form the tissues of the plant. LP
Theodore Schwann (British Zoologist): He studied different types of animal cells and Discovery of living cell
reported that cells had a thin outer layer which is today known as the ‘plasma membrane’. Leeuwenhoek examined mud, semen,
Based on his studies on plant tissues, he concluded that the presence of cell wall is a unique saliva, blood, insects, etc., and
character of the plant cells. observe protozoans, sperm, bacteria,
RBC, muscle cells, etc. He called
On the basis of this, Schwann proposed the hypothesis that the bodies of animals and plants these tiny creatures as “Animalcules”
are composed of cells and products of cells.
Rudolf Virchow: Cell theory did not explain how new cells are formed. In 1855, Rudolf
Virchow first explained that cells divided and new cells are formed from pre-existing cells
(Omnis cellula-e cellula). He modified the cell theory to give it a final shape. LP
Features of cell theory Exceptions to Cell Theory
1. All living organisms are composed of cells and products of cells. Viruses because they lack cell
organization.
2. All cells arise from pre-existing cells.
Certain cells such as RBC and
3. Each cell has a unit of heredity. Genetic information is stored as DNA in the chromosome sieve tube because of absence of
present in nucleus. nuclei in the mature state.
Prokaryotes such as bacteria and
TYPES OF CELL cyanobacteria because they lack
well-organised nucleus.
On the basis of nuclear organisation, cells are classified mainly into two types: All acellular organisms and
protists.
1. Prokaryotic cell : Lack a well-developed nucleus and membrane-bound organelles.
E.g., bacterial cell
2. Eukaryotic cell : Have a well-developed nucleus and membrane bound organelles. E.g.,
plant cell and animal cell Key Note
Onion cell is a typical plant cell which has a distinct cell wall as its outer boundary and the Viruses represent a connecting
cell membrane just within it. link between living and non-
living things
Human cheek cell is an animal cell which have an outer membrane as the delimiting
structure of the cell. Cell wall is absent in animal cells.
30 Cell: The Unit of Life
CELL: SHAPE, SIZE AND STRUCTURE
LP
E.coli bacterium can form its colonies Dense membrane bound structure is found inside each cell which is called as nucleus. This
overnight where one colony have nucleus contains chromosomes which in turn contain the genetic material, DNA.
more than 1 million bacteria which
are formed by the division of single Cytoplasm is the main arena of cellular activities which is consisted of the whole matter
bacterium. E.coli usually divides inside plasma membrane except nucleus.
once in every 20 minutes.
Cells vary greatly in their shape. Cells also differ greatly in size. They may be disc-like,
polygonal, columnar, cuboid, thread-like, or even irregular. The shape of the cell may vary
with the function they perform.
Some examples of cells and their features are given in the table below:
Key Note Cell type Feature
Mycoplasma (Smallest cell) 0.3 µm in length
Mycoplasma is an exception
where the cell wall is absent Bacteria 3-5 µm
and thus it is pleomorphic in Ostrich egg Largest isolated single cell
nature. Columnar epithelial cell Long and narrow
Mesophyll cell Round and oval
Human red blood cell (erythrocyte) Round and biconcave shaped; about 7.0 µm in
diameter;
NCERT Fill-up Nerve cells (Longest cells in humans) Branched and long
___________ is the
fundamental structural and
functional unit of all living
organisms.
___________ and
___________ together
formulated the cell theory.
Who discovered the first
living cell? ___________
Cells that have membrane
bound nuclei are called
___________ whereas cells
that lack a nucleus are called
___________.
The main arena of cellular
activities is ___________.
Fig.-1: Diagram showing different shapes of the cells
PROKARYOTIC CELLS
These cells are represented by members of kingdom monera, i.e., bacteria, blue-green
Key Note algae (Cyanobacteria), mycoplasma or PPLO (Pleuro Pneumonia Like Organisms).
Cytosol is basically the They are generally smaller and multiply more rapidly than the eukaryotic cells.
whole content of cell
Prokaryotes may vary greatly in shape and size.
inside plasma membrane
except nucleus and all cell The four basic shapes of bacteria are bacillus (rod like), coccus (spherical), vibrio (comma
organelles. shaped) and spirillum (spiral).
Cytoplasm = Cell content – Coccus Spirillum
nucleus Spherical shaped Spiral shaped
Cytosol = Cytoplasm – cell
organelles and nucleus Bacteria
Bacillus Vibrio
Rod shape Comma shaped
All prokaryotes are surrounded by plasma or cell membrane which is surrounded by a cell
wall.
Cell: The Unit of Life 31
STRUCTURAL COMPONENTS OF PROKARYOTIC CELL
LP
1. Cell Envelope and its Modifications Functions of glycocalyx
Most prokaryotic cells, particularly the bacterial cells, have a chemically complex cell It provides definite shape to the
envelope which consists of a tightly bound three layered structure cell.
It helps in recognition of
(i) Glycocalyx – Outermost layer microbes for defence.
(ii) Cell wall – Dead, middle layer It protects the underlying plasma
membrane.
(iii) Plasma membrane – Living, innermost layer
They act together as a single protective unit but each layer of the envelope performs distinct
function as well. LP
Glycocalyx can be called slime layer (in the form of a loose sheath) in some while in Cell wall of archaebacteria is made
others, it may be called the capsule (thick and tough). up of pseudomurein
On the basis of differences in the cell envelopes and the manner in which they respond to
the staining procedure developed by Gram viz., bacteria can be classified into two groups:
LP
(i) Gram positive bacteria – Their cell envelope can take up the gram stain Cell wall of eubacteria is formed
(ii) Gram negative bacteria – Their cell envelope do not take up the gram stain up of peptidoglycan (polymer
of N-acetylglucosamine and
2. Cell Wall N-acetylmuramic acid).
It determines the shape of the cell. It provides a strong structural support to prevent the
bacterium from bursting or collapsing. NCERT Fill-up
3. Plasma membrane In bacteria, the infoldings
It is semi-permeable in nature and interacts with the outside world. This membrane is of cell membrane is called
structurally similar to that of the eukaryotes (lipid bilayer with proteins embedded in it). __________, which is the
characteristic of prokaryotes.
A specialised differentiated form of cell membrane called mesosome is the characteristic
Many bacteria have small
of prokaryotes. circular DNA in addition to
It is formed by the infoldings/extension of cell membrane. These extensions are in the form genomic DNA and is called
of vesicles, tubules and lamellae. __________.
Reserve material in
Functions of mesosomes prokaryotic cell is stored
Formation of cell wall in cytoplasm in the form of
DNA replication and distribution to daughter cells __________.
Helps in respiration (equivalent to eukaryotic mitochondria), secretion processes, increase
the surface area of the plasma membrane and enzymatic content.
In some prokaryotes like Cyanobacteria, there are other membranous extensions into the LP
cytoplasm called chromatophores (equivalent to eukaryotic chloroplast) which contain Types of flagella
pigments. Monotrichous-Single flagella;
Vibrio cholerae
Motility
Amphitrichous-Single flagella on
Bacterial cells may be motile (have a thin filamentous extension of cell wall called flagella) each of the opposite ends
or non-motile.
Lophotrichous- Many flagella arise
Bacteria show a range in the number and arrangement of flagella. from same spot
Bacterial flagellum is composed of three parts: Peritrichous-Multiple flagella
present all round the bacteria; E.coli
(i) Filament – Longest portion and extends from the cell surface to the outside
(ii) Hook- Joins basal body to the filament
(iii) Basal body LP
Pili: It is elongated tubular structure made of a special protein. Conjugation is the partial DNA
transfer from donor to recipient
Fimbriae: They are small bristle like fibres sprouting out of the cell. In some bacteria,
bacterium. Sex pili are formed by
they are known to help attach or anchorage the bacteria to rocks in streams and also to the
this process.
host tissues.
32 Cell: The Unit of Life
4. Ribosomes
Ribosomes are smallest cell organelle.
Prokaryotic ribosomes are about 15 nm by 20 nm in size.
Key Note Made up of two sub units-50S and 30S units which together form 70S.
In prokaryotes, ribosomes are associated with the plasma membrane of the cell.
Within the cell, ribosomes
are found not only in the Ribosomes are known as protein factories as they are site of protein synthesis of the cell.
cytoplasm but also within the 5. Inclusion bodies
two organelles – chloroplasts Inclusion bodies store the reserve material in prokaryotic cells inside the cytoplasm.
(in plants) and mitochondria
These are not bound by any membrane and lie free in the cytoplasm. Phosphate granules,
and on rough ER. cyanophycean granules and glycogen granules are some examples of inclusion bodies.
Gas vacuoles are found in blue-green and purple and green photosynthetic bacteria.
EUKARYOTIC CELLS
The eukaryotes include all the kingdoms, i.e., protista, fungi, plantae, animalia except
kingdom monera.
Membrane bound organelles are present in eukaryotes which leads to extensive
compartmentalisation of cytoplasm.
LP
Table: Difference Between Prokaryotic and Eukaryotic Cell
Gas vacoules provide ability to float
and maintains buoyancy. They also Feature Prokaryotes Eukaryotes
protect bacteria from UV light.
Nucleus, nucleolus Absent Present
and nuclear enve-
lope
Chromosomes Nucleoid contains single Nucleus contains 2 to many
chromosome. chromosomes.
Size 0.5-10 µm 10-15 µm
Cell wall Present Present in some protists, most
fungi and all plants but absent in
animals.
LP
Plasma membrane Present Present
Mostly eukaryotes do not possess
plasmids but some lower eukaryotes Cell organelles Lacks membrane bound cell Membrane bound cell organelles
such as yeast can have plasmids. E.g. organelles are present.
Saccharomyces cerevisiae.
Ribosomes 70S type 80S type
Plasmids and pili Present Absent
Centrioles Absent Present but absent in plants
Protein synthesis Takes place in cytoplasm Takes place in nucleus and
ribosomes
Examples Bacteria, cyanobacteria, All plant and animal cells
mycoplasma, etc.
Protein Takes places in cytoplasm Transcription in nucleus &
LP synthesis translation in cytoplasm on
Nuclear material of prokaryotes ribosomes.
consists of nucleoid and circular
dsDNA. Prokaryotes have nucleoid Examples Bacteria, Cyanobacteria All plant & Animal cells
associated proteins instead of (BGA) Mycoplasma (PPLO), including human cells, protista,
histones. Rickettsias, Actinomycetes. algae, fungi, protozoa.
Cell: The Unit of Life 33
Table: Difference between animal cell and plant cell
NCERT Fill-up
Animal Cell Plant Cell
What are the two subunits
Cell walls absent Possess cellulosic cell walls of prokaryotic ribosomes?
Plastids (chloroplasts) absent Plastids present __________.
Several ribosomes may attach
Large central vacuole is not present Large central vacuole present due to which to a single mRNA and form a
nucleus is not central chain called __________.
Have centrioles and centrosomes so they Do not have centrioles In bacteria, __________
have astral cell division determines the shape of
Reserve food is glycogen Reserve food is starch cell and provides structural
support.
Surface structure present
in bacteria are flagella,
__________ and
__________.
The largest isolated single
cell is __________
LP
Term cell membrane or plasma
membrane was given by Nageli
Fig.-2: Animal Cell and Cramer.
Term unit membrane was
given by Robertson.
LP
Sandwich or Trilamellar
Model of plasma membrane
Fig.-3: Plant Cell Proposed by Danielli and
Davson in 1935.
STRUCTURAL COMPONENTS OF EUKARYOTIC CELL In this the bilayered phospholipid
is sandwitched in between two
Plasma Membrane layers of protein molecule.
It is outermost boundary of animal cell.
Plasma membrane is a thin selective permeable. Plasma membrane facilitates the transport
of the molecules across it.
It is flexible and porous membrane.
It is composed of lipids, proteins and carbohydrates.
The ratio of protein and lipid varies considerably in different cell types. Fig.: Sandwich Model
In human beings, the membrane of the erythrocyte has approximately 52 per cent protein
and 40 per cent lipids.
34 Cell: The Unit of Life
Fluid Mosaic Model
This model was proposed by Singer and Nicolson in 1972. It is the latest and most
LP
accepted model.
Unit Membrane Model According to this model, the quasi-fluid nature of lipid enables lateral movement of
Proposed by J. David Robertson proteins within the overall bilayer. This ability to move within the membrane is measured
in 1959. as its fluidity.
According to this model, all
the cellular and organelle
The fluid nature of the membrane is also important for other functions like cell growth,
membranes are structurally & formation of intercellular junctions, secretion, endocytosis, cell division, etc.
functionally similar (difference Lipids are arranged within the membrane with the polar head towards the outer sides
in chemical structure & size).
and the hydrophobic tails towards the inner part. This ensures that the non-polar tail of
saturated hydrocarbons is protected from the aqueous environment. The lipid component
of the membrane mainly consists of phosphoglycerides.
Within phospholipid bilayer, proteins are arranged in two forms:
1. Extrinsic or peripheral proteins
Fig.: Unit membrane Model
2. Intrinsic or integral proteins
Key Note
Lipids can move from one
leaflet to the other via flip-flop
movement which is absent in
proteins due to its large size
Fig.-4: Fluid mosaic model
but can show lateral movement
within the leaflet. Table: Difference between Extrinsic and Intrinsic proteins
Extrinsic Proteins Intrinsic proteins
Arranged superficially on the outer and Partially or wholly remain embedded in
LP inner surfaces of membrane phospholipid
Chemical composition of Soluble and unstable Some intrinsic proteins are confined in lipid
plasma membrane bilayer (Stable protein).
Can be easily removed by mild treatment Cannot be separated easily
Proteins Carbohydrates Lipids such as change in pH
58-60% 1-2% 20-40%
Transport of Molecules Across Membrane
1. Active transport
Occurs from lower concentration to higher concentration.
Energy is utilized in the form of ATP, e.g., Sodium-potassium pump.
2. Passive transport
Occurs from higher concentration to lower concentration.
LP
Energy is not required.
3. Diffusion
Movement of molecules from their high concentration to low concentration. If carriers are
required, then called facilitated diffusion.
As the polar molecules cannot pass through the non-polar lipid bilayer, they require a
carrier protein of the membrane to facilitate their transport across the membrane.
Water and neutral solutes may move across the membrane by simple diffusion.
Cell: The Unit of Life 35
4. Osmosis
Osmosis always occurs through semipermeable membrane in which movement of solvent LP
(water) occur. Oligosaccharides of the glycolipids
& glycoproteins on the outer surface
Functions of Plasma Membrane of plasma membranes are involved in
cell to cell recognition mechanism.
Due to the flexible nature of cell membrane, cell can grow without breakage and can divide
as well.
Formation of intercellular junctions for communication and exchange of substances.
It is protective and supportive layer.
Conduction of nerve impulse takes place through plasma membrane of nerve cell.
Plasma membrane plays an important role in recognition of various cells. E.g., macrophages
engulfs only dead RBC.
The sites for cell recognition are located on the surface of plasma membrane.
Cell Wall
Cell wall is an outer covering of plasma membrane.
It is non-living, rigid structure.
Due to presence of cell wall, plant cell can be differentiated from animal cell.
LP
Structure of the Cell Wall:
Types of osmosis
Minerals (CaCO3) (i) Endosmosis: In this,
Cellulose
Mannans which water enters from
surrounding medium in to
Galactans Hemicellulose
the cells; observed when cell
Cellulose Plants
is immersed in hypotonic
Pectins
solution.
Bacteria Algae
(Peptidoglycan) Proteins (ii) Exosmosis: In this, water
goes out of the cell into
surrounding medium;
Cell wall
observed when cell immersed
(Non-living, rigid structure) in hypertonic solution.
Primary wall Secondary wall
characteristics
Capable of growth
Cell wall of young Formed inner side of
plant cells the cell
(Towards membrane)
Diminishes as cell
matures
Middle lamella: This layer is mainly composed of calcium pectate. It holds or glues the
different neighbouring cells together.
The cell wall and middle lamella may be traversed by plasmodesmata which connect the
cytoplasm of neighbouring cells.
Functions of Cell Wall:
Cell wall protects the cell from a mechanical damage and infection.
Cell wall gives a particular size & shape to cell & functions in formation of exoskeleton LP
of cell. Fruits become soft and juicy due to
dissolving of middle lamella.
Cell wall provides barrier to undesirable micromolecules.
Cell wall helps in cell-to-cell interaction.
36 Cell: The Unit of Life
CELL ORGANELLES
LP
Mitochondria was first Cell organelles are organised cytoplasmic structure capable of growth and, in some cases,
discovered by Kolliker (1880)
as cytoplasmic granules in multiplication. They can be single or double membrane-bound.
straited muscles of insect. Cell Organelles
It was named ‘mitochondria’ by
C. Benda.
Double membrane Single membrane Non-membranous
bound bound
Nucleus, Mitochondnia Lysosomes, microbodies, Ribosome and
& plastids golgi complex, ER centriole
LP
In prokaryotes, the respiratory Mitochondria
enzyme are present on the cell Mitochondria are the sites of aerobic respiration. They produce ATP and hence is known as
membrane instead of mitochondria
power house of cell or energy currency of the cell.
(mesosome)
It is the second largest organelle in animal cells. It is semi-autonomous organelle.
Mitochondria divides by fission.
Occurrence
Mitochondria is present in all cells except RBC and prokaryotes.
LP
It is distributed throughout the cytoplasm and are localised at the sites engaged in higher
Outer membrane of mitochondria
(permeable) has more phospholipids
metabolic activities.
(phosphatidyl choline) and
Shape and size
cholesterol as compared to inner
membrane (selectively permeable). The number of mitochondria per cell is variable depending on the physiological activity
of the cells.
It is sausage-shaped or cylindrical.
It has a diameter of 0.2-1.0µm (average 0.5µm) and length 1.0-4.1µm.
Structure
LP Mitochondria is double membrane bound structure. It consists of two membranes.
Each mitochondrial membrane is 60- (i) Inner membrane forms a number of infoldings called the cristae towards the matrix.
75 Å thick and separated by a space
called perimitochondrial space. (ii) Outer membrane forms the continuous limiting boundary of the organelle.
This space is rich in coenzymes and
enzymes required for oxidation of The two membranes have their own specific enzymes associated with the mitochondrial
fats and pyruvic acid. function.
The outer and inner membrane divides its lumen distinctly into two aqueous compartments,
i.e., the outer compartment and the inner compartment.
LP
Mitochondrial matrix
constituents 1% of total DNA in
Fig.-5: Structure of mitochondrion (LS)
a cell and rich in G-C content
Enzymes for replication and Inner Membrane
transcription of DNA like It is projected into the central space in the form of finger like projections called cristae.
DNA polymerase and RNA
polymerase are also found in The cristae increases the surface area and provide abundant space for metabolism.
mitochondrial matrix.
It is selectively permeable and contains all enzymes of electron transport chain.
Cell: The Unit of Life 37
F0-F1–particles
These are present on the inner membrane of mitochondria. LP
If outer membrane of mitochondria is
F0-F1 particles contain enzyme of electron transport system and oxidative phosphorylation. removed, then structure is called as
F1 headpiece is a peripheral membrane protein complex. It contains the site for synthesis of mitoplast.
ATP from ADP and inorganic phosphate.
F0 is an integral membrane protein complex. It forms the channel through which protons
LP
cross the inner membrane.
Mitochondria also help in formation
Matrix of yolk during the development of
ovum (vitellogenesis)
Mitochondrial matrix have enzymes for Kreb’s cycle.
The matrix possesses single circular DNA molecule, a few RNA molecules, ribosomes
(70S). LP
It contains all the components required for the synthesis of proteins. Leucoplast are found in those cells
in which light is not available, e.g.,
Functions of Mitochondria underground stem and root
Mitochodria is the site for cellular respiration because it contains all enzymes required
for it.
LP
Since mitochondria is a site of cellular respiration, energy (ATP) is formed in it.
Mitochondria has important role in
During sperm maturation mitochondria help in formation of middle piece of sperm. cytoplasmic inheritance.
Plastids
Plastids are found in all plant cells and in euglenoids. They may be colourless or with LP
colour. Red colour of chillies and red
tomatoes is due to the red pigment
Based on the type of pigments, there are three types of plastids, namely leucoplast, lycopene of chromoplasts.
chromoplast and chloroplast.
Plastid NCERT Fill-up
Mitochondria and chloroplast
Leucoplast Chloroplast Chromoplast are __________ membrane-
(colourless) (Green coloured) (Coloured) bound structures.
(Store food mainly) The inner compartment
of mitochondria is called
Aleuroplast Carotene
__________ and possesses
Amyloplast (Proteins) Xanthophyll __________ DNA molecules.
(Starch) Phycoerythrin The cell organelle __________
Elaioplast
E.g., potato Phycocyanin is the site of aerobic respiration
(Fats & oil) and it divides by fission.
The __________ connect the
Table: Characteristic features of types of plastids thylakoid of different grana.
The space limited by the inner
Leucoplast Chromoplast Chloroplast membrane of chloroplast is
called __________.
White or colourless Blue, red or yellow Green
Plastids are classified, based
Their shapes and sizes varies Contains fat soluble Contains chlorophyll and on the __________, into
with stored nutrients: carotenoid pigment like carotenoid pigments which chloroplasts, __________ and
__________.
Amyloplasts store carotene, xanthophylls are responsible for trapping
carbohydrates (starch), e.g., light energy essential for The space limited by inner
membrane of the chloroplast is
potato. photosynthesis. called __________.
Elaioplsts store oils and Colour giving pigments are
fats, e.g., oil seed present in __________ type of
plastid.
Aleuroplasts store proteins, Chloroplast contain __________
e.g., maize type of ribsomes.
38 Cell: The Unit of Life
Chloroplast
LP Due to the presence of chlorophyll, leaves and other parts of plants exhibits green colour.
Quantasomes are photosynthetic These are found in the mesophyll cells of leaves and chlorenchyma region of higher plants.
functional units, which consists
of about 230 to 400 molecules of Shape and size
various pigments (Chl-a, Chl-b, These are lens-shaped, oval, spherical, discoid or even ribbon-like organelles.
carotenes, xanthophylls etc.)
They are variable in length (5-10 μm) and width (2-4 μm). Their number varies from 1 per
cell of Chlamydomonas, a green alga, to 20-40 per cell in mesophyll.
Structure
It is a double membrane bound organelle with an outer membrane (permeable) and an
inner membrane (less permeable).
Key Note The space limited by the inner membrane of the chloroplast is called the stroma.
The ribosomes of the A number of organized flattened membranous sacs called the thylakoids, are present in
chloroplasts are smaller (70S) the stroma
than the cytoplasmic ribosomes Thylakoids are arranged in stacks like the piles of coins (one above other) called grana.
(80S).
There are flat membranous tubules called the stroma lamellae that connect the thylakoids
of the different grana.
The membrane of the thylakoids encloses a space called lumen.
The stroma of the chloroplast contains enzymes required for the synthesis of carbohydrates
and proteins.
Chlorophyll is the main pigment of chloroplast. It is present in thylakoid. The following
LP
types of chlorophylls are found in plants:
Carotenoids
Yellowish - orange colour of (i) Chlorophyll a: Found in all photosynthetic organism except photosynthetic bacteria,
fruits are due to α-carotene, so it is also called as universal chlorophyll.
β-carotene and γ-carotene. (ii) Chlorophyll b: Found in all higher plants and in green algae but not present in algae
Xanthophylls : Yellow of other group.
coloured carotenoids are also
(iii) Chlorophyll c: Found in brown algae and diatoms.
called Xanthols.
Fucoxanthin is found in brown (iv) Chlorophyll d: Found in red algae.
algae which provides brown Functions:
colour to algae.
Chloroplasts are the sites of photosynthesis. Light reaction occurs in thylakoids while dark
reaction occurs in stroma.
Chloroplasts help in maintaining balance of oxygen and carbon dioxide in atmosphere.
ENDOMEMBRANE SYSTEM
All organelles are quite different in terms of structure and function but many of these are
considered together as endomembrane system as their functions are coordinated.
Endomembrane system includes Endoplasmic Reticulum, Golgi Complex, lysosomes
and vacuoles.
Mitochondria, chloroplast and peroxisomes are not considered as the parts of endomembrane
system because their functions are not coordinated with ER, golgi complex, lysosomes and
vacuoles.
Endoplasmic reticulum
Endoplasmic reticulum is a network of tiny tubular structures scattered in the cytoplasm.
LP Its one end is connected with nuclear membrane whereas the other end with plasma
membrane.
ER is absent in prokaryotes, present
in all eukaryotes except germinal ER divides the intracellular space into two distinct compartments
cells and mature mammalian (i) Luminal compartment (inside ER)
erythrocytes.
(ii) Extra luminal (cytoplasm) compartment
Cell: The Unit of Life 39
It consists of three morphological forms viz., cisternae, vesicles and tubules.
LP
Cisternae
These are elongated flattened,
unbranched tubular structure
which are found arranged in
parallel rows.
These are generally granular due
to presence of ribosome.
They are mainly found in cells
actively indulged in protein
synthesis like in liver, pancreas,
etc.
Fig.-6: Endoplasmic reticulum LP
Types of Endoplasmic Reticulum Sarcoplasmic Reticulum is SER
occurs in skeletal and cardiac
SER(Smooth Endoplasmic reticulum) - Ribosomes are absent.
muscles. It stores Ca+2 and energy rich
RER(Rough Endoplasmic Reticulum) - Ribosomes are found on the surface of ER. compounds required for contraction
of muscles.
Table: Difference between SER & RER
Rough endoplasmic reticulum (RER) Smooth endoplasmic reticulum (SER)
Ribosomes are present on their surface Due to absence of ribosomes, they appear
LP
smooth
In the plant cells, a number of Golgi
Involved in active synthesis of proteins and Site for synthesis of lipid, steroidal hormones bodies are scattered regularly in
secretion processes (in animal cells) and their storage. the cytoplasm. These are called
Eg. Adipose tissue, Muscles Eg. Liver, Pancreas dictyosomes.
Functions:
ER acts as cytoskeleton and provide mechanical support and shape to the cell.
SER helps in lipid synthesis of lipids and steroid hormones. LP
RER is frequently observed in the cells actively involved in protein synthesis and secretion. Golgi bodies are pleomorphic
structures because component of
Golgi Complex Golgi body are differ in structure &
shape in different cells.
It was discovered by Camilo Golgi (1898) who observed densely stained reticular structures
near the nucleus.
They consist of many flat, disc-shaped sacs or cisternae of 0.5µm to 1.0µm diameter.
Cisternae are stacked parallel to each other. Varied number of cisternae are present in a LP
Golgi complex. All the macromolecules which are to
be sent outside the cell, move through
Each Golgi stack or cisternae has two faces
the Golgi body. Hence, Golgi body
(a) Cis or forming or convex face is termed as ‘Principal director of
(b) Trans or maturing or concave face macromolecular traffic in cell’ or
‘Middle men of cell’.
The cis and the trans faces of the organelle are entirely different, but interconnected.
LP
Vesicles
These are rounded, oval
structures found well-scattered
in the cytoplasm and granular.
They are mainly found in protein
Fig.-7: Golgi complex forming cells.
40 Cell: The Unit of Life
Functions
LP Sort and package materials, to be delivered either to the intracellular targets or secreted
Tubules outside the cell.
These are irregular, tubular, Modify ribosomal proteins in the cisternae before they are released from its trans face.
highly branched structures Site of formation of glycoproteins and glycolipids.
found near the cell membrane.
It appears smooth due to lack of Why the golgi apparatus remains in close association with the endoplasmic reticulum?
ribosomes. Because the materials to be packaged in the form of vesicles from the ER fuse with the
These are mainly found in cis face of the golgi apparatus and move towards the maturing face.
cells associated with synthesis
of cholesterol, glycerides,
hormones, etc. Lysosome
These are membrane bound vesicular structures formed by the process of packaging in the
golgi apparatus.
LP The isolated lysosomal vesicles have been found to be very rich in almost all types of
hydrolytic enzymes (hydrolases – lipases, proteases, carbohydrases) optimally active at
Cis face receives vesicles the acidic pH.
containing enzyme or protein
from the ER. It is directed ●● Lipases- Catalyzes breakdown of lipids
towards nucleus. ●● Proteases- Catalyzes breakdown of proteins
Trans face releases modified ●● Carbohydrases- Catalyzes breakdown of carbohydrates
enzymes or proteins containing
Golgi vacuoles. It is directed ●● Nucleases- Catalyzes breakdown of nucleic acids
towards plasma membrane.
Ribosome
Ribosomes are the granular structures. They are first observed under the electron microscope
as dense particles by George Palade (1953).
LP Ribosome are also known as “organelle within an organelle” and “protein factory of
When ER is broken into fragments cell”.
and centrifuged, small granular
In eukaryotes, ribosomes are scattered in the cytoplasm and attached to endoplamic
structures are obtained called
microsomes.
reticulum and outer nuclear membrane.
Ultrastructure:
Key Note Each ribosome composed of two subunits, i.e., larger and smaller subunits.
Ribosome is composed of ribonucleic acid (RNA) and Protein (ribonucleoprotein).
When cells are old, diseased or
injured, lysosomes attack their Types:
cell organelles and digest them. Ribosome is mainly of two types:
In other words lysosomes are
autophagic, i.e., self devouring. 1. 70S Ribosome
Therefore, lysosomes are also ●● It
is found in prokaryotes. 70S ribosome have two subunits: 50S (larger) and 30S
called suicidal bags. (smaller).
2. 80S ribosomes
●● It is found in eukaryotes. It is composed of two subunits 60S (larger) and 40S (smaller)
LP
●● Here
‘S’ (Svedberg’s Unit) stands for the sedimentation coefficient; it is indirectly a
Lysosome involves in the digestion
measure of density and size.
of excessive secretory granules
of hormone in endocrine gland
lysosomes. This event is called Polyribososmes or Polysome: At the time of protein synthesis, many ribosomes get
crinophagy. attached with mRNA and known as polyribosome or polysome.
mRNA
LP
Ribosome
Lysosome get originated from :–
Plasma membrane by the process
of pinocytosis or phagocytosis.
Golgi complex. DNA Polyribosome
Endoplasmic reticulum.
Cell: The Unit of Life 41
Function of ribosome
Main function of ribosome is protein synthesis, thus called protein factory or cell engine. LP
Cytoskeleton Cell secretion Involve Three Steps :
(i) Golgi body recieve the materials
An elaborate network of filamentous proteinaceous structures present in the cytoplasm is from ER through its cis-face.
collectively referred to as the cytoskeleton. (ii) Materials are chemically
Functions of Cytoskeleton modified by Golgi body. For e.g.,
Glycosidation (Glycosylation)
Mechanical support of proteins and lipids takes
Motility place in Golgi body and it yields
glycoprotiens and glycolipids).
Maintenance of the shape of the cell
(iii) After chemical modification,
Cilia and Flagella materials are packed in vesicles.
These vesicles are pinched off
Small structures work like oars from trans face of golgi body
Cilia Causing the movement of either and discharged outside the cell
the cell or the surrounding fluid (reverse pinocytosis).
Cilia and
Flagella
Hair like outgrowths of the cell membrane
and are covered with cell membrane
Emerge from centriole like structure called
the basal bodies
NCERT Fill-up
Core ‘or’ filament is called axoneme con-
tain number of microtubules What is the main function of
Comparatively longer and ribosomes? __________.
Flagella responsible for cell movement Which type of ribosomes are
present in prokaryotic cell
?__________
The endomembrane system
includes __________ and
__________.
The ER, bearing __________ on
their surface is called RER.
The Golgi cisternae are
concentrically arranged near the
nucleus with distinct convex
‘cis’ or the __________ face and
concave ‘trans’ or __________
Fig.-8: Diagrammatic representation of internal structure of cilia/flagella face.
The lysosomal vesicles are rich
Table: Difference between cilia and flagella in __________ enzymes that are
optimally active in __________
Cilia Flagella
pH.
Size Small (5-10μm) Long (up to 150 μm)
Number per cell Very large Few in number
Movement Cilia beat in a coordinated manner Flagella beats independently
(non-coordinated manner)
Function They take part in locomotion, Flagella involved in locomotion.
attachment, feeding and sensation. LP
Microtubules form a
Centrosome & Centrioles cytoskeleton and are responsible
Centrosome is an organelle usually containing two cylindrical structures called centrioles. for maintaining the shape of the
cell.
They are surrounded by amorphous pericentriolar materials.
Microtubules radiate from the
Both the centrioles in a centrosome lie perpendicular to each other in which each has an centrosphere around centriole
organisation like the cartwheel. and form spindle fibre.
They are made up of nine evenly spaced peripheral fibrils of tubulin protein.
42 Cell: The Unit of Life
Each of the peripheral fibril is a triplet. The adjacent triplets are also linked.
LP The central part of the proximal region of the centriole is also proteinaceous and called
Microfilaments are composed of the hub.
contractile protein actin.
Hub is connected with tubules of the peripheral triplets by proteinaceous radial spokes.
Functions
Key Note
Formation of basal body of cilia and flagella
In many cells, food vacoules
Helps in formation of spindle apparatus during cell division in animal cells
are formed by engulfing the
food particles. E.g., protists. Vacuole
The vacuole is the membrane-bound space found in the cytoplasm. It is bound by a single
membrane called tonoplast.
In plant cells, the vacuoles can occupy up to 90 per cent of the volume of the cell.
NCERT Fill-up It contains water, sap, excretory product and other materials not useful for the cell.
A network of filamentous Functions of vacuole
proteinaceous structures present
in the cytoplasm is called
In plants, the tonoplast facilitates the transport of a number of ions and other materials
__________ against concentration gradients into the vacuole, hence their concentration is significantly
Which cell organelle is higher in the vacuole than in the cytoplasm.
surrounded by amorphous
pericentriolar material?
In Amoeba, the contractile vacuole is important for osmoregulation and excretion.
__________.
Cilia and flagella are emerge Nucleus
from centriole – like structure The cell nucleus was discovered by Robert Brown in 1831.
called __________.
The space between two parallel Later the material of the nucleus stained by the basic dyes was given the name chromatin
membranes of nuclear envelope by Flemming.
is called __________.
Nucleus is double membrane bound organelle, which controls all cellular metabolism and
The nuclear matrix is called
__________, which contain encloses the genetic information of cell.
__________ and chromatin.
Structure:
Nucleolus is a main site for
synthesis of __________ 1. Nuclear envelope
The spherical structure
present in the nucleoplasm is Electron microscopy has revealed that the nuclear envelope which consists of two parallel
______________. membranes.
The interphase has highly The space between two membranes (10 to 50 nm) called the perinuclear space. It forms a
extended and elaborate
nucleoprotein fibres called barrier between the materials present inside the nucleus and that of the cytoplasm.
______________. The outer membrane usually remains continuous with the endoplasmic reticulum and also
bears ribosomes on it.
At a number of places the nuclear envelope is interrupted by minute pores called nuclear
pores, which are formed by the fusion of its two membranes.
Nuclear pore allows the movement of RNA and protein molecules in both directions
between the nucleus and the cytoplasm.
Key Note 2. Nucleoplasm
Normally, there is only one Nuclear matrix or the nucleoplasm contains nucleolus and chromatin.
nucleus per cell, variations in
the number of nuclei are also (a) Nucleolus
frequently observed. Some ●● The content of nucleolus is continuous with the rest of the nucleoplasm as it is not a
mature cells even lack nucleus,
e.g., erythrocytes (RBCs) of membrane bound structure.
many mammals and sieve tube
●● Nuceolus is a site for active ribosomal RNA synthesis. Larger and more numerous
cells of vascular plants.
nucleoli are present in cells actively carrying out protein synthesis.
Cell: The Unit of Life 43
(b) Chromatin
●● The interphase nucleus (nucleus of a cell when it is not dividing) has highly extended
and elaborate nucleoprotein fibres called chromatin, nuclear matrix and one or more
LP
spherical bodies called nucleoli. The nucleoli are spherical structures present in the Chromatin is of two types:
(a) Euchromatin: Lightly stained
nucleoplasm. and diffused part of chromatin.
It is transcriptionally or
●● Chromatin are loose and indistinct network of nucleoprotein fibres. genetically more active. It lies at
central part of nucleus.
●● Chromatin contains DNA and some basic proteins called histones, some non-histone (b) Heterochromatin: Dark
stained, thick and condensed part
proteins and also RNA. of chromatin. It is genetically
less active chromatin and forms
stop point in transcription. It
Chromatin = DNA + RNA + histone proteins + non-histone proteins occurs near nuclear membrane.
●● Chromatin contains genetic material in the form of chromosomes.
Functions of Nucleus:
Nucleus contains genetic information in the form of multiple linear DNA molecules
organised into structures called chromosomes . LP
It transfers genetic information from one generation (parent cell) to next (daughter cell). Calcium is essential for maintenance
of nucleolus. It disappears during late
Division of nucleus is pre-requisite to cell division. prophase and reappears in telophase
stage.
Nucleus controls metabolism of cell by sending mRNA in cytosol
Variation develops due to change in genetic material of nucleus.
Chromosomes
A single human cell has approximately two metre long thread of DNA distributed among
its forty six (twenty three pairs) chromosomes.
Every chromosome essentially has a primary constriction or the centromere. Key Note
Formation of ribosome is the
Chromosomal theory of inheritance was given by Sutton & Boveri. chief function of nucleolus,
thus called ribosome factory of
Structure
the cell.
Chromosomes are rod-like, elongated structures.
Each chromosome consist of a single long thread of DNA associated with histone.
Centromere (Primary constriction)
Every chromosome (visible only in dividing cells) essentially has a primary constriction or
the centromere on the sides of which disc shaped structures called kinetochores are present.
Centromere holds two chromatids of a chromosome.
Kinetochores contitute the actual site of attachement of spindles to chromosomes during
cell division.
At the region of centromere, the chromosome is comparatively narrower than remaining
part of chromosome, thus it is termed as primary constriction.
44 Cell: The Unit of Life
Types of chromosomes
LP On the basis of position of centromere, chromosome are of 4 types.
Chromosomes can be best studied 1. Metacentric chromosome: Centromere is located in the middle which forms two equal
at metaphase stage because size
arms of the chromosome
of chromosome is shortest during
metaphase due to highly condensed 2. Sub-metacentric chromosome: Centromere is located slightly away from the middle of
chromatin threads. the chromosome and results into one shorter arm and one longer arm
3. Acrocentric chromosome: Centromere is situated close to its end forming one extremely
short and one very long arm
4. Telocentric chromosome: Centromere is situated at one end.
LP
Secondary constriction
Besides primary constrictions, one
or two other constriction may also
present on some chromosome,
these are known as secondary
constriction. Secondary constriction
is also known as NOR (Nucleolar Telocentric
Acrocentric
organiser region) sub- Metacentric
metacentric
Fig.-9: Types of chromosomes
Microbodies
Microbodies are single membrane bound small spherical structures found in both plant
and animal cells. They contain various enzymes.
Topic-wise Questions
8. Cells in which nucleus is bounded by membrane are known
An Overview Of Cell & Cell Theory
as
1. Robert Hooke discovered a. Prokaryotic cell b. Eukaryotic cell
a. Cell wall b. Mitochondria c. Bundle sheath cell d. All of these
c. Cytoplasm d. Nuclei
9. Which of the following is present in both prokaryotic and
2. Living beings are made up of cells. This statement belongs
eukaryotic cell?
to
a. Vacuoles b. Vesicle
a. Lamarck b. Von Helmont
c. Plastids d. Cell membrane
c. Hugo de Vries d. Schleiden and Schwann
10. The easiest way to differentiate a prokaryotic cell from a
3. Theodore Schwann named the outer layer of the cell which is
today known as eukaryotic cell is to check for
a. Plasma membrane b. Cell membrane a. Cell membrane b. Nucleus
c. Basement membrane d. Biological membrane c. DNA d. Carbohydrates
4. Who proposed the theory that “cells arise only from the pre- 11. On the basis of size the correctly matched pair is
existing cells”? a. Mycoplasma – 0.3 μm
a. Mohl b. Virchow b. Bacteria – 3-5 μm
c. Haeckel d. Brown
c. RBC – 7 μm in diameter
5. Cell theory as understood today describes that:
d. All of these
a. All living organisms are composed of cells and products of
cells 12. Which organelle is not visible when student observes a
b. All cells evolve from pre-existing cells human cheek cell under a microscope?
c. Plants and animals possess exactly same type of Cellular a. Nucleus b. Endoplasmic reticulum
components is plant and animals are same c. Nucleus d. Chloroplast
d. More than one option is true 13. Which of the following is the smallest cell of human body?
6. Which of the following statement is false? a. Erythrocyte b. Monocyte
a. Single celled organisms are capable of independent c. Leucocytes d. Blood platelets
existence
14. The largest isolated single cell is
b. Any structure less than a complete structure of a cell does
not ensure independent living a. Red Blood cells b. PPLO
c. According to Matthias Schleiden, a German zoologist, the c. Ostrich egg d. Mast cells
body of animals are composed of cells and its products
15. Read the following statements:
d. Schledien and Schwann together formulated the cell
theory A. The shape of cell may vary with the function they
perform
7. Which of the following statements depicts the fundamental
B. Nerve cells are the longest cells
features of cell theory?
A. All cells share similar physiology and chemistry C. Egg of an ostrich is the largest isolated single cell
B. All living organisms are made up of cells and their D. Blue-green algae is a eukaryote
products. E. Prokaryotic cells are generally smaller and multiply
C. Each cell is made up of a small mass of protoplasm slowly than eukaryotic cells
having a nucleus inside and a plasma membrane with or choose the incorrect statements.
without a cell wall. a. Two b. Four
D. Activities of an organism are the sum total of activities
and interaction of its constituents cells. c. Three d. One
Correct option with respect to the statement is 16. Which is not found in prokaryotic cell?
a. Only B is correct b. A and C are correct a. Plasma membrane b. Nuclear membrane
c. A, C and D are correct d. All of these c. Cell wall d. Ribosomes
46 Cell: The Unit of Life
17. Which of the following is present only in prokaryotic cell? 28. The basic shape of bacteria is/are
a. Phagosome b. Lysosome a. Bacillus b. Vibrio
c. Mesosome d. ER c. Spirillum d. All of these
18. Jelly like semifluid complex of cytoplasm is called 29. Which one of the following cell is long and narrow in shape?
a. Endoplast b. Cytosol a. Mesophyll cell
c. Cytoplasmic matrix d. Both (b) and (c) b. WBC
19. Which of the following organelles are not bounded by c. Columnar epithelial cells
membrane?
d. Tracheid
a. Nucleus & golgi body
30. Which of the following cell is branched and long?
b. Mitochondria & vacuoles
a. RBC b. WBC
c. Nucleolus & ribosome
c. Nerve cell d. Mesophyll cell
d. Golgi body & endoplamic reticulum
31. Human red blood cell is
20. Non-membranous organelle is
a. Round and biconcave b. Flat and discoid
a. Chloroplast b. Nucleolus
c. Discoid d. Round and flat
c. Centriole d. Both (b) and (c)
32. Select the odd one out w.r.t. shapes of bacteria:
21. Which of the following organelles is/are double membrane-
a. Coccus – Spherical
bound?
a. Nucleus b. Chloroplast b. Bacillus – Comma
c. Mitochondria d. All of the above c. Spirillum – Rod-like
22. A single unit membrane organelle is d. Vibrio – Rod-like
a. Ribosomes b. Mitochondria
Prokaryotic Cells
c. Chloroplast d. Lysosomes
23. In a prokaryotic cell, 33. Genetic material of prokaryotic cells is known as
A. Genetic material is enveloped a. Nucleus b. Centrosome
B. Absence of ribosomes c. Nucleoid d. Chromosome
C. An organised nucleus is absent. 34. Out of the following which structure is not present in a
The correct option is prokaryotic cell?
a. Only B b. Only A a. Nuclear envelope b. Mesosome
c. Only C d. All of these c. Pili d. Cell membrane
24. Which of the following structures would you expect to find in 35. Cell wall of prokaryotes is made up of
a bacterium? a. Chitin b. Sulphur
a. RER b. Plasma membrane c. Cellulose d. Peptidoglycan
c. Golgi apparatus d. Lysosome 36. In bacteria, small circular DNA is present outside the genomic
25. Out of lysosomes, peroxisomes and mitochondria, unit DNA. This is called
membrane is present in a. Mesosome b. Plastid
a. Both peroxisomes and lysosomes
c. Plasmid d. Inclusion body
b. Both peroxisomes and mitochondria
c. Only lysosomes 37. Which of the following option is correct w.r.t. plasmids?
d. All of these a. They are much smaller than nucleoid
26. Which of the following is NOT a true organelle? b. They confer some unique phenotypic character to the
a. Lysosome b. Ribosome concerned bacteria
c. Chloroplast d. Mitochondria c. These are covalently closed double stranded circular DNA
27. Within the cell, ribosomes are found not only in cytoplasm d. All of these
but also within the two organelles. This statement is true for- 38. How plasmid and mesosomes are same?
a. All prokaryotic organisms a. Both of them are made up of nucleotides
b. All eukaryotic organisms b. Both of them are concerned with molecular respiration
c. All bacterial and animal cells c. Both of them are seen in prkaryotic cell
d. Both (a) and (c) d. Both of them are seen in eukaryotic cell
Cell: The Unit of Life 47
39. Mesosomes are the infolding of cell membrane. They 49. Gas vacuoles are found in
A. Helps in cell wall formation, DNA replication and a. Blue-green photosynthetic bacteria
respiration. b. Purple and green photosynthetic bacteria
B. Increases the surface area of plasma membrane. c. Both (a) and (b)
C. Are present in both prokaryotic and eukaryotic cells. d. All bacteria
Choose the correct option. 50. Which type of ribosomes are found in Nostoc cells?
a. B and C b. A and C a. 50S b. 60S
c. A and B d. A, B and C c. 70S d. 80S
40. In prokaryotes, chromatophores are
Eukaryotic Cells
a. Specialized granules responsible for colouration of cells.
b. Structures responsible for organizing the shape of the 51. Which of the following is a characteristic feature that
organism. differentiate plant cell from animal cell?
c. Inclusion bodies lying free inside the cells for carrying out a. Presence of chloroplast b. Presence of mitochondria
various metabolic activities. c. Presence of vacuoles d. Absence of cell wall
d. Internal membrane system which becomes extensive and 52. Animal cells do not have cell wall because
complex in photosynthetic bacteria. a. They are adapted to move their body
41. Bacteria show a range in the number of arrangement of b. They have muscles and nerves
flagella. Bacterial flagellum is made up of c. They have to change the size of their body during
a. Two parts – pili and fimbriae locomotion
b. Three parts – filament, hook and shaft d. All are correct
53. A plant cell constitutes
c. Three parts – filament, shaft and basement membrane
a. Rigid cell wall and a large central vacuole
d. Three parts – filament, hook and basal body
b. A centriole for spindle formation
42. The longest part of the bacterial flagellum that extends from
c. A centrosome inactive in non-dividing cells
the cell surface to the outside is known as
d. Absence of plasma membrane
a. Filament b. Hook
54. Which of the following statement is correct?
c. Basal body d. Shaft
a. Both plant cell and animal cell possess plastids.
43. Which of the following is correct for Pili? b. Only animal cells possess plastids.
a. It is a surface structure of bacteria help in motility c. Only plant cells possess plastids.
b. Found in both gram positive and gram negative bacteria d. Both plant cell and animal cell lack plastids.
c. Made up of pilin and flagellin
d. Helps in mating process Cell Membrane
44. Small bristle like fibres present in bacteria are: 55. Plasmalemma is another term for
a. Inclusion bodies b. Pili a. Cell wall b. Middle lamella
c. Flagella d. Fimbriae c. Microfibrils d. Plasma-membrane
45. Prokaryotic ribosomes are 56. The barrier between the protoplasm and the outer environment
in an animal cell is
a. 40 S b. 80 S
a. Cell wall b. Plasma membrane
c. 70 S d. 50 S
c. Nuclear membrane d. Cytoplasm
46. Larger subunit of ribosome is in prokaryotic cell is
57. Lipid bilayers in biomembranes are barrier to
a. 40 S b. 70 S
a. Polar molecules
c. 50 S d. 80 S b. Non-polar molecules
47. Several ribosomes may attach to a single mRNA strand and c. Both polar and non-polar molecules
form a chain known as d. None of these
a. Polyribosome b. Polysome
58. According to the fluid mosaic model of plasma membrane
c. Mesosome d. Both (a) and (b)
a. The top layer is hydrophilic and non-polar in nature
48. Polyribosomes are aggregates of b. Polar layer is hydrophobic
a. Only rRNA b. DNA and rRNA c. Phospholipids form a middle bimolecular layer
c. Ribosomes and mRNA d. Lysosomes d. Middle layer is formed by proteins
48 Cell: The Unit of Life
59. Glycoproteins are known to play an important role in cell 68. The fluid nature of the membrane is important because it is
recognition, the specificity of this recognition is largely involved in
provided by a. Cell growth and cell division
a. Lipid portion of glycoproteins b. Endocytosis and secretion
b. Protein portion of glycoproteins c. Intercellular junction formation
c. Carbohydrate portion of glycoproteins d. All of these
d. Both carbohydrate and protein components of 69. One of the following does not support facilitated transport.
glycoproteins a. This requires energy input
60. Which macromolecules are present in the cell membrane? b. This is passive process
a. Only proteins c. Solutes are moved by a change in shape in the carrier
protein
b. Lipids and proteins
d. The solute can move in either direction
c. Lipids, proteins and carbohydrates
70. One of the following methods for transporting substances
d. Only lipids across a membrane does not involve a change in extrinsic
61. Most abundant lipid found in plasma membrane is and intrinsic proteins
a. Glycolipids b. Phospholipids a. Na-K pump b. Active transport
c. Integral lipids d. Cholestrol c. Simple diffusion d. Facilitated diffusion
62. Cell membranes posses lipid, protein and carbohydrate. The 71. Read carefully and mark the incorrect
ratio of protein and lipid varies considerably in different a. Na+ & K+ can move across membrane through active
cell types. In human beings, the membrane of the RBCs has transportation
approximately b. Water can pass with the concentration gradient through the
a. 40 per cent lipids and 52 per cent carbohydrates nonpolar lipid bilayer
b. 40 per cent protein and 52 per cent lipids c. Non polar molecules can not pass through nonpolar lipid
c. 40 per cent lipids and 52 per cent proteins bilayer
d. 40 per cent protein and 52 per cent carbohydrates d. Neutral solute can move according to concentration
gradient across the nonpolar lipid bilayer
63. Plasma membrane, particularly in animal cells, is elastic due
to 72. Chemical nature of carrier molecules facilitating transport
across plasma membrane is
a. Carbohydrates b. Proteins
a. Starchy b. Sugary
c. Lipids d. None of these
c. Proteinaceous d. Fatty acidic
64. On the basis of ease of extraction, membrane proteins can be
categorized as 73. Sodium-Potassium (Na+/K+) pump is an example of:-
a. Unsaturated proteins and saturated a. Passive transport b. Translocation
b. Hydrophobic proteins and hydrophilic c. Active transport d. Osmosis
c. Integral and peripheral proteins Cell Wall
d. Acidic, basic and neutral proteins
74. In algae, cell wall is made up of
65. The quasifluid nature of _________ allows _________
movement of proteins within the bilayer of a cell membrane a. Cellulose b. Galactans & Mannans
c. Calcium carbonate d. All of the above
a. Protein, Lipid b. Lipid, lateral
c. Protein, flip-flop d. Lipid 75. Cell wall in higher plants is made up of
a. Cellulose + Lignin b. Cellulose + Pectin
66. Which of the following is not a characteristic of the fluid
c. Cellulose + Suberin d. Cellulose + Lipid
mosaic model for biological membranes?
a. Fluidity 76. Choose the correct sequence of layers of bacterial cell
envelope is
b. Components are symmetrically distributed
a. Cell membrane → Glycocalyx → Cell wall
c. Membrane components that can move about
b. Glycocalyx → Cell wall → Cell membrane
d. Structure reflects function
c. Cell wall → Glycocalyx → Cell membrane
67. Which of the following is true regarding fluid mosaic model? d. Glycocalyx → Cell membrane → Cell wall
a. Single phospholipid layer is present over protein layer 77. Which of the following layer is present nearest to the plasma
b. Phospholipid bilayer is present over carbohydrate layer membrane in plant cell?
c. Intrinsic proteins are embedded in phospholipid bilayer a. Tonoplast b. Middle lamella
d. Between two layers of protein, phospholipid is present c. Primary wall d. Secondary wall
Cell: The Unit of Life 49
78. On which side of the plasma membrane, the secondary wall 88. Organelle involved in modification and transportation of
is formed? newly synthesised proteins to their destination is
a. Outer (towards middle lamella) side of the cell a. Chromoplast b. Vacuoles
b. Inner (towards middle lamella) side of the cell c. Glyoxysomes d. Endoplasmic reticulum
c. Inner (towards membrane) side of the cell 89. Which structures are responsible for lipid synthesis
d. Outer (towards primary cell wall) side of the cell respectively in plants and animal cells?
79. Which of the following statement is incorrect? a. Smooth E. R.
a. Middle lamella is mainly made up of calcium pectate b. Smooth and rough E. R.
b. Primary cell wall is the cell wall of a young plant cell c. Smooth E. R. and sphaerosomes
c. Plasmodesmata are cytoplasmic bridges that connect the
d. Sphaerosomes and smooth E. R.
neighbouring plant cells
d. Secondary wall is formed on the outer side of the cell Golgi Apparatus
80. The cytoplasm of neighbouring cells are connected through
a. Vacuole b. Plasmodesmata 90. Diameter of Golgi cisternae is:
c. Polysomes d. Middle lamella a. 0.5 µm – 1.0 µm b. 0.2 – 1.0 µm
81. Which of the following depicts the function of cell wall? c. 1.0 – 4.1 µm d. 10 – 50 nm
a. Provide shape of the cell and protects the cell from the 91. The components of Golgi apparatus are
mechanical damage and infection a. Single membrane bound
b. Helps in interacting with surrounding cells
b. Double membrane bound
c. Act as a barrier to undesirable macromolecules
c. Single membrane bound cisternae and double membrane
d. All of these
bound
82. A structure that connect the cytoplasm of surrounding cells,
and another which attaches different neighbouring cell d. Single membrane bound cisternae and double membrane
together are called bound tubules and vacuole
a. Plasma membrane and middle lamella, respectively 92. Select the three morphological forms of Golgi apparatus
b. Plasmodesmata and middle lamella, respectively a. Lamellae, tubules and cisternae
c. Middle lamella and peroxisomes, respectively b. Cisternae, tubules and vesicles
d. Cell wall and plasmodesmata, respectively c. Granum, tubules and vesicles
d. Granum, thylakoids and lamellae
Endoplasmic Reticulum
93. Which organelle of plant cells secretes polysaccharide and
83. Select the organelle which is directly attached to the outer
protein to make cell walls?
membrane of the nucleus in a eukaryotic cell?
a. Golgi bodies b. Lysosome
a. Plastids b. Mesosome
c. Golgi apparatus d. Endoplasmic reticulum c. Mitochondria d. Chloroplast
84. An organelle in which there is interconnected membranous 94. Which of the following is not a function of golgi apparatus?
network of vesicles, flattened sacs and tubules is a. Synthesis of glycoproteins
a. Mitochondria b. Endoplasmic reticulum b. Packaging materials
c. Vacuoles d. Plastids c. Modification of proteins
85. Function of RER is d. Secretion of hydrolytic enzymes
a. Synthesis of proteins b. Formation of microbodies 95. Golgi body is associated with
c. Synthesis of lipids d. Synthesis of glucose
a. Packaging and storage of material
86. What is the function of smooth endoplasmic reticulum?
b. Cell plate formation
a. Protein synthesis
c. Secretion of different substance
b. Cell wall formation
c. Lipid synthesis d. All of the above
d. Chloroplast synthesis 96. Which of the face, Golgi complex is associated with ER?
87. Which cell organelle is associated with synthesis of lipid-like a. Forming face, i.e., Trans-face
steroidal hormones? b. Maturing face, i.e., Trans-face
a. Golgi body b. RER c. Both forming and maturing face
c. SER d. Vesicles d. Forming face or Cis-face
50 Cell: The Unit of Life
108. Cristae are present in
Lysosomes
a. Surface of grana
97. Which cell organelles contains hydrolytic enzymes? b. Plasma membrane’s surface
a. Mesosome b. Lysosome c. Mitochondrial inner membrane
c. Peroxisomes d. Golgi apparatus d. Membrane of nucleus
98. Which cell organelle secretes lipases, proteases, 109. Respiratory enzymes are present in
carbohydrases? a. Mitochondria b. Chloroplasts
a. Golgi body b. SER c. Golgi bodies d. Lysosomes
c. Nucleus d. Lysosomes 110. Oxidative enzymes occurs mostly in
99. Lysosomal enzymes are active at a. Lysosomes b. Golgi bodies
a. Neutral pH b. Basic pH c. Mitochondria d. Ribosomes
c. Acidic pH d. Any of these 111. Which one separates the mitochondrial core from outside?
a. Outer membrane b. Inner membrane
Vacuoles c. Perimitochondrial space d. All the above
100. Outer covering of vacuole is called 112. The inner compartment of mitochondria is filled with a dense
a. Sarcolemma b. Plasmalemma homogeneous substance called
c. Cell wall d. Tonoplast a. Matrix b. Stroma
101. In Amoeba, the contractile vacuole is important for c. Cisternae d. Cristae
a. Osmoregulation b. Respiration 113. Outer and inner membranes of mitochondria are
c. Cell secretion d. Food storage a. Structurally and functionally similar
102. In plant cells, _______% volume of the cell is occupied by b. Structurally and functionally dissimilar
vacuole. c. Structurally similar but functionally different
a. 80 b. 65 d. Structurally different but functionally similar
c. 95 d. 90
114. Small particle projecting from inner surfaces of cristae and
inner mitochondrial membrane are
Mitochondria
a. Microsomes b. Oxysomes
103. Given below are the features of Mitochondria:- c. Myeloid bodies d. Informosomes
A. They are easily visible under the microscope (without
specifically stained) 115. Which of the following representation correctly explain the
B. They are sausge-shaped or cylindrical shaped function of mitochondrion
C. They are bounded by double membrane O2 H 2O
D. They possess two aqueous compartments.
a. A, D are correct and B, C are incorrect a. ADP M ATP
b. A, B are correct and C, D are incorrect
c. A is incorrect and B, C & D are correct CO2
d. A, D are incorrect and B, C are correct Phosphate
CO2 H2O
104. Infoldings of inner mitochondrial membrane are called
a. Cristae b. Cisternae
c. Thylakoids d. Grana b. ADP M AMP
105. Organelles which helps in the production of energy is
Phosphate CO2
a. E.R b. Ribosomes
c. Mitochondria d. Golgi body
CO2 H 2O
106. F0 - F1 particles are found in
a. Inner mitochondrial membrane
c. ADP M AMP
b. Mitochondrial surface
c. Grana
Phosphate O2
d. Intermembrane space
107. In which of the following cell organelles would you expect to CO2 H2O
find the biochemical reactions that harness energy from the
breakdown of sugar molecules to synthesise large amounts of
ATP? d. ADP M ATP
a. Lysosome b. Vesicles
c. Chloroplast d. Mitochondria Phosphate O2
Cell: The Unit of Life 51
116. Organelles which are referred as ‘power house’ of the cell 127. In green plants, majority of chloroplasts are present in
and in which the oxidative phosphorylation takes place is a. Mesophyll cells b. Bundle sheath cells
called c. Vascular cells d. Spongy cells
a. Plastids b. Endoplasmic reticulum
128. Aleuroplast is responsible for the storage of
c. Golgi apparatus d. Mitochondria a. Vitamins b. Chlorophyll
c. Proteins d. Water
Plastids 129. Ripen fruits are brightly coloured due to
117. Which of the following stores oils and fats? a. Aleuroplast b. Elaioplast
a. Aleuroplast b. Amyloplast c. Amyloplasts d. Chromoplasts
c. Leucoplast d. Elaioplast 130. Extra chromosomal DNA occurs in
a. Chloroplast b. Ribosomes
118. Carbohydrates are stored in c. Nucleus d. Chromosomes
a. Leucoplast b. Aleuroplast 131.. Which of the following plastid contain photosynthetic
pigment?
c. Amyloplast d. Elaioplast
a. Leucoplasts b. Chloroplasts
119. Stacks of membranous flattened discs in chloroplasts are
c. Chromoplasts d. None of these
called
a. Cristae b. Thylakoids 132. Carotene, xanthophylls are the types of pigments found in
c. Grana d. Stroma a. Chloroplasts b. Amyloplasts
c. Chromoplasts d. None of these
120. The number of chloroplast varies from 1 per cell of ...A... to
...B... per cell in the mesophyll. 133. Select the semi-autonomous cell organelles from the
a. A—Chlorella, B—15 to 20 following
b. A—Chlamydomonas, B—20 to 40 a. Nucleus and golgi body
c. A—Chlamydomonas, B—15 to 20 b. Chloroplast and mitochondria
d. A—Chlamydomonas, B—10 to 40 c. Lysosomes and Golgi complex
d. Ribosome and mitochondria
121. Both mitochondria and chloroplasts
134. The thylakoid in chloroplast are arranged as
a. Have double membranes.
a. Interconnected disc b. Interconnected sacs
b. Have highly structured inner membranes.
c. Stacked discs d. None of these
c. Present only in eukaryotic cells.
d. All of these Ribosomes
122. Colourless plastids are known as 135. Ribosomes are first observed under the electron microscope
a. Chloroplast b. Leucoplast as dense particles by
c. Protoplast d. Chromoplast a. Palade b. Robert Brown
123. Select the colorless plastid which is involved in fat storage? c. Schwann d. Matthian Schleiden
a. Aleuroplast b. Chromoplast 136. The larger subunit of 80S ribosome is
c. Etaioplast d. Etioplast a. 50S b. 60S
124. Grana and stroma are the parts of which cell organelles? c. 40S d. 30S
a. Mitochondria b. Chloroplast 137. Select the nucleoprotein structure from the following?
a. Virus b. Ribosome
c. Ribosome d. Golgi bodies
c. Chromatin d. All of these
125. What is the function of amyloplasts?
138. Which one is not correctly matched?
a. Store carbohydrates or starch a. Golgi apparatus-Breaking of complex macromolecules
b. Provide colour to various flowers and fruits. b. Endoplasmic reticulum-Protein synthesis
c. Mitochondria-Oxidative phosphorylation
c. Help in photosynthesis.
d. Chloroplasts-Photosynthesis
d. Provide support to the plants 139. Sedimentation coefficient(s) in ribsomes is used as a measure
126. The plastids that aids in storage of nutrients are of
a. Lycopene b. Leucoplasts a. Size b. Density
c. Elaioplast d. Chromoplast c. Volume d. Both (a) and (b)
52 Cell: The Unit of Life
140. In an animal cell, protein synthesis takes place 147. Select the incorrect statement with respect to centrosome and
a. On ribosomes present in cytoplasm as well as in centrioles:-
mitochondria. A. Centrosomes are surrounded by amorphous pericentriolar
material
b. On ribosomes present in the Plastids as well as in
B. In centrosome, both centrioles lie parallel to each other
cytoplasm.
in which each has an organisation like the cartwheel
c. Only on ribosmes attached to the golgi apparatus and C. Centrioles are composed of nine unevenly placed
endoplasmic reticulum. peripheral fibrils of dynein protein
d. Only on the ribosomes present in cytoplasm. D. Hub is the central proteinaceous part of centriole
E. Proteinaceous radial spokes connect hub to peripheral
Cytoskeleton, Cilia and Flagella triplets
a. A, B & E b. Only C
141. Which of the following provides mechanical support and
c. B & C d. All are correct
shape to the cell?
148. Protein tubulin is absent in
a. Golgi complex b. Centrioles
a. Nucleus b. Centrosome
c. Lysosomes d. Cytoskeleton
c. Chromatin d. Plasma membrane
142. An elaborate network of filamentous proteinaceous structures 149. The organelle devoid of DNA but capable of duplication is
consisting of microtubules, microfilaments and intermediate
a. Plastids b. Nucleus
filaments present in the cytoplasm is collectively referred to
c. Centriole d. Mitochondria
as
150. Centrosomes and centrioles are present in
a. Axoneme b. Centrosome
a. Green plants b. Animal cell
c. Cytoskeleton d. Centriole
c. Bacteria and protista d. Both (a) and (b)
143. Read the following statements:
151. Which of the following has centrioles?
A. Cilia and flagella work like an oar
B. Cilia are relatively longer as compared to flagella. a. Chromosomes b. Spindle fibres
C. The structure of Prokaryotic and eukaryotic flagella are c. Centrosomes d. Centromeres
same
D. Plasma membrane covers cilia and flagella in Nucleus and Microbodies
eukaryotes.
E. Axoneme is the core of cilia and flagella which 152. Read the given statements and select the ones which are true
has nine pairs of doublets of radially arranged (T) or false (F)
peripheral microtubules and a pair of centrally located A. Mitochondrial matrix have 70S ribosomes
B. DNA of E.coli is not associated with histone proteins
microtubules.
C. Plasmids are self replicating, extra chromosomal
How many of the above statements are correct?
segments of single stranded, circular, naked DNA
a. Three b. Two A B C
c. Four d. Five a. F T T
144. Flagellum and cilium arise from centriole-like structure b. T T F
known as c. T F T
a. Hook b. Filament d. F T F
c. Basal body d. Centromere 153. A chromosome in which centromere is sub-terminal is
145. The core of cilia or flagella possesses a number of called
a. Microtubules b. Microfilaments a. Metacentric b. Acrocentric
c. Intermediate filaments d. None of these c. Telocentric d. Sub-metacentric
154. Chromosome having centromere located in its middle is
Centrosome and Centrioles a. Acrocentric b. Telocentric
c. Metacentric d. Sub-metacentric
146. Which organelle is important in spindle formation during
nuclear division? 155. Active ribosomal synthesis takes place in
a. Centriole b. Endoplasmic reticulum a. Golgi body b. Mitochondria
c. Nucleus d. Mitochondria c. Nucleolus d. Cytoplasm
Cell: The Unit of Life 53
156. Match the following- c. Chromatin d. Both (a) and (c)
A. Robert Brown 1. Ribonucleoproteins 160. The material of the nucleus stained by the basic dyes was
B. Flemming 2. Nucleus as a cell organelle given the name chromatin by
C. Palade 3. Densely stained reticular a. Flemming b. Brown
structures c. Palade d. Golgi
D. Camillo Golgi 4. Staining of nucleus material 161. Which structure is present in chromosomes?
a. A-1 B-2 C-3 D-4 a. Nucleus b. Centromere
b. A-2 B-4 C-3 D-1 c. Centrosome d. Golgi body
c. A-2 B-4 C-1 D-3 162. Nucleous helps in the synthesis of
d. A-4 B-3 C-2 D-1 a. dsDNA b. Lysosomes
157. Name the type of chromosome, in which one arm is very long c. RNA d. ssDNA
and one other is very short? 163. The part of the nucleus that plays major role for synthesis of
a. Acrocentric b. Submetacentric ribosome:
c. Metacentric d. Telocentric a. Chromatin reticulum b. Nuclear pore
158. In which of the following nucleus is absent? c. Nucleoplasm d. Nucleolus
a. Mature RBC b. Mature sieve tube 164. Membrane bound minute vesicles that contain various
enzymes and found in both plant and animal cells are
c. In all matured cells d. Both (a) and (b)
a. Centrioles b. Chromosome
159. The nuclear matrix is made up of
a. Nucleolus b. DNA and RNA c. Microbodies d. Mesosomes
Morale Booster Questions
1. Which of the following cell organelle take part in 9. Fluid mosaic model of plasma membrane was put forward by
photorespiration? a. Melvin Calvin b. Schleiden and Schwann
a. Glyoxisome b. Peroxisome c. Singer and Nicolson d. Robert Hook
c. Dictyosome d. E.R.
10. Tonoplast can be defined as
2. All plastids have similar structure because they can a. Inner membrane of mitochondria
a. Store starch, lipids and proteins
b. Inter membrane space of chloroplast
b. Get transformed from one type to another
c. Membrane boundary of the vacuole of plant cells
c. Perform same function
d. Cell membrane of a plant cell
d. be present together
11. Select the incorrect option for an eukaryotic cell?
3. Which option does not hold true for ribosomes?
a. Cell wall is made up of peptidoglycans
a. Has two sub-units
b. Ribosome present in the cytoplasm is 80s type
b. Form polysome or polyribosome
c. May attach to mRNA c. Mitochondria has circular DNA
d. Has no role in synthesis of proteins d. Organelles present are bounded by membrane
4. Which one of these is not an example of eukaryotic cell? 12. What would happen if lysosomes get ruptured in a cell?
a. Euglena b. Anabaena a. Cell dies
c. Spirogyra d. Agaricus b. Cell shrinks
5. Golgi apparatus is absent in c. Cell swells up
a. Higher plants d. Nothing would happen
b. Yeast 13. Which of the following features mark the difference between
c. Bacteria and Blue-green algae mitochondria and plastids?
d. Liver cells a. Presence of double membrane
b. Presence of DNA
6. Satellite means
c. Presence of thylakoids
a. Terminal part of the chromosome beyond secondary
constriction. d. Presence of ribosome
b. Terminal part of the chromosome beyond primary 14. Which of the following is not a function of cytoskeleton in a
constriction. cell?
c. Terminal part of chromosome beyond tertiary constriction. a. Intracellular transport
d. None of the above b. Maintenance of cell shape and structure
c. Support of the organelle
7. Arrange the following cells in an ascending order of their
d. Cell motility
size.
15. Nucleosome contains
I. PPLO II. Egg of ostrich
a. Nucleolus b. Genes
III. Human RBC IV. Bacteria
c. Microfilaments d. Histones
Choose the correct option from the following
16. Centre of phosphorylation is
a. I, IV, III, II b. I, II, Ill, IV
a. Ribosome b. Mitochondria
c. II, I, III, IV d. III, II, I, IV
c. Vacuoles d. Lysosome
8. Outer and inner membranes of mitochondria are
17. Organelles are present only in prokaryotic cells are
a. Structurally and functionally similar
[Vacuoles, Mesosomes, Ribosomes, Flagella, Cell wall,
b. Structurally and functionally dissimilar Mitochondria]
c. Structurally similar but functionally different a. 1 b. 5
d. Structurally different but functionally similar c. 2 d. 6
Cell: The Unit of Life 55
18. Bacterial cells have a chemically complex cell envolope. The 27. In chloroplasts the chlorophyll is located in
cell envelope consists of a tightly bound three layer structure, a. Stroma b. Grana
i.e., the c. Pyrenoid d. Both A and B
a. Outermost cell wall followed by the plasma membrane 28. Hydrolytic enzymes such as lipases, carbohydrases and
and then the glycocalyx proteases are present it
b. Outermost glycocalyx followed by plasma membrane and a. Lysosome b. Inclusion bodies
the cell wall
c. Vacuoles d. Mitochondrion
c. Outermost cell wall followed by the glycocalyx and then
29. Select the correct axonemal arrangement of microtubules
the plasma membrane
from the following
d. Outermost glycocalyx followed by the cell wall and then
a. 8 peripheral pairs of doublets and one central pair of
the plasma membrane.
singlet
19. Given below are the statements with regard to the functions b. 6 peripheral pairs of doublets and one central singlet
performed by Golgi apparatus?
c. 9 peripheral pairs of doublets and one central pair of
(i) Transportation and chemical modifications of the singlet
materials present in it. d. 9 peripheral pairs and one central singlet
(ii) Performs the function of packaging materials. 30. Chloroplasts in higher plant are _____ shaped
(iii) Glycoproteins and glycolipids are formed in it. a. Kidney b. Lens
Which of the following is true? c. Bean d. Dome
a. (i) is wrong but (ii) and (iii) are correct 31. Which of the following sequence is correct for the origin of
b. (ii) is wrong but (i) and (iii) are correct lysosome
c. (ii) and (iii) are wrong but (i) is correct a. Endoplasmic reticulum - Golgi complex - Lysosomes
d. All options are correct b. Nuclear membrane - Golgi complex - Lysosomes
c. Endoplasmic complex - Vacuoles - Lysosomes
20. Organelle in which cristae are present
d. Mitochondria - Golgi complex - Lysosomes
a. Ribosome b. Mitochondrion
32. What is common between chloroplasts, chromoplasts and
c. Chloroplast d. Lysosome
leucoplasts?
21. Shape of chromosomes is determined by position of a. Presence of pigments
a. Centrosome b. Centromere b. Presence of thylakoids and grana
c. Telomere d. Mitcromere c. Storage of starch, proteins and lipids
d. Ability to multiply by a fission-like process
22. A cell organelle in prokaryotes is concerned with storage of
reserve food materials, such as cyanophycean granules, etc. 33. Order the following terms in a way that depicts how
It is not bonded by any membrane. Identify it among the membranes are likely to move through the cell
following A. Endoplasme B. Nuclear membrane
a. Lysosomes b. Peroxisomes C. Glolgi body D. Vesicle
c. Plastids d. Inclusion bodies E. Cell membrane
a. A → B → C → D → E
23. The chromosome which lacks a centromere is
b. A → D → B → A → C → B → E
a. Acentric b. Acrocentric
c. B → E → A → D → E → C
c. Metacentric d. Telocentric
d. B → A → D → C → D → E
24. Water soluble materials pass through 34. Structural element of chromatin is
a. Extrinsic proteins b. Channel proteins a. Histone b. Acid protein and DNA
c. Spectrin d. Glycoprotein c. Nucleosome d. Nuclear matrix
25. The lipid component of the cell membrane mainly consists of 35. Given below are some features of a cell organelle. Identify
a. Triglycerides b. Phosphoglycerides the organelle which shows all the features described above
c. Glycolipids d. Mono and diglycertides (i) It is a membrane bound space present in the
cytoplasm.
26. Which organelle is responsible for the production of
(ii) It is bound by a unit membrane known as tonoplast.
lysosomes?
a. Golgi complex b. Nucleus (iii) It contains water, sap, excretory products and other
materials not useful to the cell.
c. Plasma membrane d. Vacuoles
56 Cell: The Unit of Life
(iv) Concentration of sap is higher than the cytoplasm. 42. In “Singer and Nicolson” model of plasma membrane, the
extrinsic proteins are
a. Mitochondria b. Vescicles
a. Tightly associated with intrinsic protein and can be easily
c. Endoplasmic reticulum d. Vacuoles
separated
36. In cold weather, the fluidity of plasma membrane in plant cell b. Loosely associated with intrinsic protein
is maintained by,
c. Loosely associated with intrinsic protein and can be easily
a. By increasing the number of phospholipids with separated
unsaturated hydrocarbon tails. d. Loosely associated with intrinsic protein and can’t be
b. By increasing the proportion of integral proteins. easily separated
c. By increasing the concentration of cholesterol in 43. Chloroplast does not contain
membrane. A. Double membraned envelope
d. By increasing the number of phospholipids with saturated B. Grana and Stroma
hydrocarbon tail. C. Matrix and Cristae
37. Chromosomes are concerned with D. Circular DNA and 70S ribosomes
a. Respiration a. A and D b. A and C
b. Growth c. C only d. B and D
c. Transmission of hereditary characters 44. According to fluid mosaic model (proposed by Singer &
Nicolson), plasma membrane is composed of
d. Assimilation
a. Cellulose, hemicellulose
38. A student placed two cells in the same solution in two b. Phospholipid and integrated protein
different containers. The observation was given in the table. c. Phospholipid, extrinsic protein, intrinsic protein
Container Observation d. Phospholipid and hemicellulose
1. Cell burst 45. Keeping in view, the Fluid mosaic model for the structure
of cell membrane, which one of the following statements is
2. Cell does not change its shape
correct with respect to the movement of lipids and proteins
Which structure maintains the shape of the cell present in from one lipid monolayer to the other described as flip-flop
container 2 and provides the most significant difference movement?
between the two cells? a. Both lipids and proteins can flip-flop
b. While lipids can rarely flip-flop, proteins cannot
a. Nucleus b. Cell wall
c. While proteins can flip-flop, lipids cannot
c. Chloroplast d. Cell membrane d. Neither lipids, nor proteins can flip-flop
39. A cell organelle ‘X’ is divided into two types on the basis of a 46. Major function of golgi apparatus is,
cell organelle ‘Y’, that helps in the protein synthesis. Identify a. In trapping the light and transforming it into chemical
‘X’ and ‘Y’ respectively. energy
a. Golgi complex and ribosome b. Helps in digesting carbohydrates and proteins
b. SER and mitochondria c. Work as energy transferring organelles
c. RER and ribosome d. In post-translational modification of proteins and
d. Lysosome and ER glycosylation of lipids
40. If living cells similar to those found on earth, were found
47. Bacterial cells are often seen in hypotonic environment.
on another planet where there was no oxygen. Then the
Which of the following characteristics keeps them from
probability of absence of which cell organelle is high?
continuing to take on water from their environment?
a. Cell wall b. Ribosome
a. The presence of a cell wall allows a buildup of turgor
c. Mitochondria d. Centromere pressure that prevents any more water from entering the
41. If P - 70S ribosomes, Q - 80S ribosomes, R - single circular cell.
DNA, S - RNA molecules, T - double helical DNA, U - b. The presence of a cell wall allows a buildup of tonic
thylakoids and V - stromal lamelllae, which of the following pressure that prevents any more water from entering into
set is found in mitochondria? the cell.
a. Q, S, T, U b. S, T, U, V c. The cell excrete out water as soon as it takes it up.
c. P, S, T d. P, R, S d. All of these.
Cell: The Unit of Life 57
48. You are monitoring the diffusion of a colored molecule across likely which of the following?
a membrane. Which of the following will result in the fastest a. Cytosol b. Mitochondria
rate of diffusion?
c. Lysosomes d. Golgi bodies
a. An internal concentration of 5 percent and an external
concentration of 60 percent. 52. Most wild plants contain toxins that deter animals from
eating them. A scientist discovered that a toxin produced
b. An internal concentration of 60 percent and an external
by a certain plant was also toxic to the same plant if it was
concentration of 3 percent.
applied to the roots of the plants. As the first step in finding
c. An internal concentration of 35 percent and an external out why the plant was not normally killed by its own toxin, he
concentration of 40 percent. fractionated some plant cell and found that the toxin was in
d. Both (a) and (b) the fraction that contained the largest cell organelle. He also
found that the toxin was no longer toxic after it was heated.
49. You are asked to observe a cell using a powerful light
Which of the following statement are consistent with the
microscope. The image you see has a clearly defined nucleus
scientist’s observations?
and mitochondria. It also has a large central vacuole and
A. The toxin was stored in the central vacuole
plastids. From what group of organisms did this cell most
B. The toxin can cross the plasma membrane but not the
likely come? membrane of the organelle in which it is stored
a. Bacteria b. Slime moulds C. The toxin was stored in the chloroplast
c. Euglenoids d. Plants D. The toxin is likely to be lipid soluble
50. You have found a mass of cells in the sediment surrounding E. The toxin may be an enzyme
a thermal vent in the ocean floor, the salinity in the area is a. A, B and E b. A, D and E
quite high. On observing the cell under microscope you find c. B and C d. C and E
no evidence of membrane-bound organelles. How would you 53. It is important that certain free ribosomes bind to the outer
classify this cell? surface of the endoplasmic reticulum (ER) in order to
a. As a eukaryotic cell complete their protein synthesis because
a. The ER membrane will break down without the presence
b. As a prokaryotic cell of numerous ribosomes.
c. As a member of domain Archaeabacteria b. It helps in synthesis of certain proteins to be completed in
d. Both (a) and (b) the cytosol.
c. It prevents the possibility that the synthesis of certain
51. Centrifugation of a cell results in the rupture of the cell
proteins, such as lysosomal hydrolases, would go to
membrane and the contents compacting into a pellets in completion in the cytoplasm.
the bottom of the centrifuge tube. Bathing this pellet with d. Ribosomes associated with mitochondrial must transcribe
a glucose solution yields metabolic activity including the proteins encoded for, by mitochondrial DNA in this
production of ATP. One of the contents of this pellet is most manner.
Multi-Concept Questions
5. Find out the correct match with regard to stored food
Matching Type Questions
A. Aleuroplasts–Proteins
1. Match the columns I and II, and choose the correct B. Elaioplasts–Fats and Oils
combination from the following options. C. RER - Glycogen
D. Amyloplasts –Starch
Column I Column II
a. A & B only b. A, B, C & D
A. Osmosis 1. Without use of energy
c. A, B, & D d. A, C and D
B. Active transport 2. Utilization of energy
molecules like ATP 6. Match the columns and find out the correct combination
C. Passive transport A. Lysosomes 1. Synthesis of proteins
a. A-1 B-2 C-2 B. Ribosomes 2. Hydrolytic activity
b. A-2 B-1 C-2 C. SER 3. Synthesis of steroids
c. A-1 B-2 C-2 D. Centriole 4. Glycolytic activity
d. A-1 B-2 C-1 E. Chromosomes 5. Repository of genetic
2. Choose the incorrect match information
6. Formation of spindle
a. Nucleus — RNA
fibres
b. Lysosome — Protein synthesis
c. Mitochondria — Respiration a. A-2 B-1 C-3 D-6 E-5
b. A-6 B-3 C-4 D-5 E-1
d. Cytoskeleton — Microtubules
c. A-1 B-4 C-3 D-6 E-1
3. Match the columns and choose the correct option d. A-4 B-3 C-1 D-2 E-5
I II 7. Some cellular structures bounded by single or double
A. Viruses 1. 1.2 µm membranes, while some other without a membrane. Match
the organelle in List I with the nature of membrane in List II
B. PPLO 2. 10-20 µm
and select the correct answer using the codes given below the
C. Eukaryotic cell 3. About 0.1 µm lists.
D. Bacterium 4. 0.02-0.2 µm A. Mitochondria 1. Without membrane
B. Lysosomes 2. Single membrane
a. A-1 B-2 C-3 D-4
C. Ribosomes 3. Double membrane
b. A-4 B-3 C-2 D-1
D. Nucleus 4. Double membrane with pores
c. A-1 B-3 C-2 D-4
a. A-1 B-4 C-3 D-2
d. A-4 B-2 C-3 D-1
b. A-3 B-1 C-2 D-4
4. Study the following table about the discoverer and the c. A-3 B-2 C-1 D-4
function of a cell organelle. d. A-2 B-4 C-1 D-3
Cell organelle Discoverer Function 8. Match the columns and find out the correct combination
I. Ribosomes Palade Synthesis of proteins A. Suicidal bags 1. Mitochondria
II. Golgi complex Golgi Synthesis of DNA B. Power house 2. Lysosomes
C. Brain of cell 3. Nucleous
III. Chromatin Flemming Complex of DNA
and proteins D. Chlorophyll 4. Chloroplast
IV. Nucleus Robert brown Cell plate 5. Nucleus
a. A-2 B-4 C-5 D-3
Which two show the correct combination?
b. A-1 B-4 C-5 D-3
a. I and II b. II and III c. A-2 B-1 C-5 D-4
c. III and IV d. I and III d. A-2 B-4 C-5 D-1
Cell: The Unit of Life 59
9. Match the columns and find out the correct combination 13. Choose the correct match.
A. Cellular extensions 1. Pseudopodia A. Microtubules – Structural components of cilia
B. Contractile fibrils 2. Myonemes B. Centrioles – Store house of hydrolytic enzymes
C. Short hair like organelles 3. Cilia C. Amyloplasts – Store oil protein and starch in plants
D. Whiplike organelles 4. Flagella a. A, B and C b. B and B
c. A only d. A and C
a. A-1 B-2 C-3 D-4
b. A-1 B-3 C-4 D-2 Image Based Questions
c. A-4 B-3 C-1 D-2 14. Consider the following five statements ( A to E) w.r.t
d. A-3 B-2 C-1 D-4 chloroplast shown below. Select the correct option stating
which ones are True (T) and which ones are False (F)
10. Match the columns and find out the correct combination
A. Axoneme 1. Peripheral tubules of basal granule
B. Doublets 2. Core of flagella
C. Singlets 3. Pairs of arms
D. Triplets 4. Central tubules of axial filament
5. Peripheral tubules of axial filament
a. A-3 B-5 C-4 D-1 A. It is impermeable and lack porins
b. A-1 B-4 C-5 D-2 B. It is selectively permeable having carrier proteins for
c. A-2 B-5 C-4 D-1 transport
d. A-1 B-3 C-4 D-5 C. Stalked thylakoids one over other which is the site of
production of assimilatory power
11. Match the columns and find out the correct combination D. Present between two grana and contains enzymes of dark
A. Endoplasmic reticulum 1. Stack of cisternae reaction
B. SER 2. Store oils or fats E. It contains enzymes for the synthesis of sugar and
proteins
C. Dictyosome 3. Synthesis of lipids A B C D E
D. Peroxisome 4. Photorespiration a. F T T T T
E. Elaioplasts 5. Synthesis of proteins b. F T T F T
c. T F T T T
a. A-5 B-3 C-1 D-4 E-2 d. T F F T T
b. A-5 B-3 C-2 D-4 E-1 15. P, Q, R and S are four types of eukaryotic cells. Which of the
c. A-2 B-3 C-1 D-4 E-5 following statement is correct regarding the given cells?
d. A-4 B-3 C-1 D-5 E-2
e. A-3 B-5 C-1 D-4 E-2
12. Match the columns and find out the correct combination
P Q
A. Golgi apparatus 1. Forms and stores starch
B. Amyloplast 2. Involved in photorespiration
C. Peroxisomes 3. Glycoproteins and glycolipids
formation
D. Endoplasmic 4. Protein synthesis
reticulum
5. Osmoregulation
R S
a. A-2 B-3 C-5 D-1
a. S helps in the water and mineral transport in xylem
b. A-4 B-5 C-1 D-2 b. In P and S nucleus is absent
c. A-5 B-4 C-2 D-3 c. Q shows amoeboid movement
d. A-3 B-1 C-2 D-4 d. All of these
60 Cell: The Unit of Life
16. Identify correct options a. A - Satellite, B-Secondary constriction C- Short arm, D-
Long arm
b. A - A satellite, B - Centromere, C- Short arm, D- Long
arm
c. A - Secondary constriction, B - Satellite C - Long arm, D
- Short arm
d. A - NOR, B- secondary constriction C - Short arm, D -
Long arm
20. Provide a name to the structure labeled in the given figure of
a. 1 = Outer membrane, 3 = Granum, 6 = Stroma endoplasmic reticulum.
b. 2 = Inner membrane, 3 = Stroma, 6 = Stromal lamellae
c. 1 = Outer membrane, 4 = Thylakoid, 5 = Stroma
d. 2 = Inner membrane, 3 = Thylakoid, 6 = Matrix
17. For a substance passing through a membrane by simple
diffusion, select the curve in the following figure that best
shows the relationship between its concentration outsides the
membrane and its rate of movement through the membrane. a. Vescicles b. Cisternae
c. Cristae d. Ribosomes
21. Choose the incorrect statement w.r.t the given organelle
A
B
C D E
a. A and B are mitochondrial membranes
a. A b. B b. Oxysomes are located on E
c. C d. D c. Kreb’s cycle occur in C
18. Different parts of mitochondria is mentioned in the given d. Glycolysis occur in D
figure. Select the one which helps in increasing the surface
22. Match the components A, B, C, D and E in the diagram (cell
area.
membrane) below from the list (i) to (vii)
X
a. X b. Y
c. Z d. Both (a) and (c) (i) Sugar (ii) Protein
(iii) Lipid bilayer (iv) Integral protein
19. Find out the correct option on the basis of following (v) Cytoplasm (vi) Cell wall
diagrams (vii) External protein
a. A - (i) B - (vii) C - (iii) D - (iv) E - (v)
b. A - (i) B - (i) C - (iii) D - (iv) E - (v)
c. A - (i) B - (ii) C - (iii) D - (iv) E - (vi)
d. A - (i) B - (ii) C - (iii) D - (vii) E - (v)
Cell: The Unit of Life 61
23. Select the alternative giving correct identification and 27. Which of the following statement is correct regarding
function of the organelle ‘A’ in the diagram. vacuole?
a. It is membrane-bound and contains storage proteins and
lipids.
b. It is membrane-bound and contains water and excretory
substances.
c. It lacks membrane and contains air.
d. It lacks membrane and contains water and excretory
substances.
28. Select the wrong statement of a bacterial cell
a. Mesosome is formed by extensions of plasma membrane
into cell
b. Pili are elongated tubular structures made up of a protein
a. Endoplasmic reticulum -synthesis of lipids c. Flagellum is composed of filament, hook and basal body
b. Mitochondria - produce cellular energy in the form of ATP d. Ribosomes are 80s type.
c. Golgi body - provides packaging material
29. Choose the incorrect statement
d. Lysosomes - secrete hydrolytic enzymes
a. The shape of the cell may vary with the function they
Statement Based Questions perform.
b. The plasma membrane is the main area of cellular activities
24. Which of the following statement is true for a secretory in both, plant and animal cell.
cell? c. Ribosomes are not bounded by membrane.
a. Golgi apparatus is absent d. Animal cell contain a non-membrane bound organelle
b. Rough Endoplasmic Reticulum (RER) is easily observed called centriole which helps in cell division.
in the cell.
30. Incorrect statement is
c. Only Smooth Endoplasmic Reticulum (SER) is present
a. All eukaryotic cells are not identical.
d. Secretory granules are formed in nucleus
b. Plant cells possess cell walls, plastids and a large central
25. The correct statement w.r.t to bacterial cell is/are? vacuole, which are absent in animal cell.
(i) Extensions of plasma membrane into the cell leads c. Animal cells have centrioles and dictyosomes which are
to the foromation of mesosome.
absent in almost all plant cells.
(ii) Has elongated tubular structures made up of a d. Eukaryotic genetic material is organised into chromosomes.
protein called pilli.
31. “Many membrane bound minute vesicles called microbodies
(iii) Flagellum is composed three parts namely filament,
hook and basal body. that contain various enzymes are present in both plant and
animal cells”.
(iv) Ribosomes are 80s type.
Above statement is correct for:
a. (i), (ii) and (iii) b. (ii) and (iii) a. Organelle participating in photorespiration along with
c. (ii) and (iii) d. None of these chloroplast and mitochondria.
26. Read the following statements and choose the correct one b. Plant lysosomes.
A. In prokaryotic cell, outgrowth of plasma membrane into c. Organelle having catalase as a marker enzyme.
cell is called polysome. d. All of these
B. SER is major site for synthesis of glycoprotein. 32. Choose the correct statement.
C. RuBisCO is most abundant protein of biosphere.
a. Unicellular organisms can exist independently
D. Mitochondria, chloroplasts and glyoxysomes are not
b. Single celled organisms are able to perform all essential
part of endomembrane system. functions of life
Which of the following statements are correct?
c. Anything less than a complete structure of a cell does not
a. C and D b. C and B ensure independent existence
c. B and D d. A and B d. All of these
62 Cell: The Unit of Life
33. Read the following statement and state true (T) or false (F). 38. Which out of the following, statements regarding osmosis is
A. The content of nucleolus is in continuation with the rest not correct.
part of the nucleoplasm. a. Osmosis refers to the movement of water across the
B. In the chromoplast, water soluble carotenoid pigments concentration gradient.
like carotene and xanthophyll are present. b. In osmosis, water moves to equalize solute concentrations
C. 9 + 2 arrangement of microtubules is seen the basal body on either side of the membrane.
of flagellum of bacteria. c. If osmosis occurs across a membrane, then diffusion will
a. T, F, F b. F, T, T not occur.
c. T, F, T d. T, T, F d. The water movement across a membrane can affect the
wall pressure of some cells.
34. Choose the correct set of statements.
A. In plants and animals cytoplasm act as the main arena of
Assertion & Reason
cellular activities.
B. Cell envelope in bacteria is loosely linked 8 - layered Directions: These questions consist of two statements each,
structure. printed as Assertion and Reason. While answering these questions,
C. Semi-autonomous organelles are not included in you are required to choose any one of the following four responses.
endomembrane system.
D. Convex side of golgi bodys is called a maturing face. A. If both Assertion and Reason are True and Reason is
correct explanation of the Assertion.
a. A & D b. A & C
B. If both Assertion and Reason are True but Reason is
c. A, B, D d. All of these
not correct explanation of the Assertion.
35. Incorrect statement is/are C. If Assertion is True but Reason is False.
A. All cells arise from pre-existing cells. D. If Assertion is False but Reason is True.
B. Various chemical reactions occur in cytoplasm to keep
39. Assertion: Cell membrane shows quasifluid behavior.
the cell in the living state.
C. Plant cell have centrioles which are absent in almost all Reason: In cell membrane, integral proteins are partially or
animal cells. totally buried in the membrane.
D. The lipid component of the plasma membrane mainly 40. Assertion: Cells are variable in shape, they may be round,
consists of phosphoglycerides. biconcave, amoeboid, columnar or even irregular.
a. A, C and D b. C only Reason: Different cell perform different functions.
c. B and D d. B only
41. Assertion: The cristae decreases the surface area of the inner
36. Statement which are true w.r.t mitochondria and Chloroplast. membrane.
A. Both the organelle helps in generation of ATP. Reason: The cristae is the folding of inner membrane of
B. Outer membrane has more surface area in both of them mitochondria.
C. They posses circular naked DNA, RNA and 70S
42. Assertion: Larger and more numerous nucleoli are present in
ribosomes cells actively carrying out protein synthesis.
D. Both take part in oxidative phosphorylation
Reason: Nucleolus is the main site for active ribosomal
a. Only A b. Only B
protein synthesis.
c. A and C d. A and B
43. Assertion: Mesosomes are analogues to mitochondria.
37. Unicellular organism like Amoeba engulf complete cells for
Reason: Mesosomes are invaginations of cell membrane in
food. Which of the following depicts the manner in which bacterial cytoplasm.
amoeba “eat”?
a. Amoeba binds only what it has receptors for, the amoeba’s Statement Type Questions
cell membrane surrounds the cell to be digested, a vesicle
forms, and the vesicle fuses with a lysosome for digestion. Directions: These questions consist of two statements each,
printed as Statement-I and Statement-II. While answering these
b. Amoeba’s cell membrane surrounds the cell to be digested
in a vesicle, and the vesicle fuses with a lysosome for questions, you are required to choose any one of the following
digestion. four responses.
c. The cell is taken into the vacuole of Amoeba a vesicle A. Both Statement-I and Statement-II are correct.
is formed, and the vesicle fuses with a lysosome for B. Both Statement-I and Statement-II are incorrect.
digestion. C. Statement-I is correct & Statement-II is incorrect.
d. All of these D. Statement-I is incorrect & Statement-II is correct.
Cell: The Unit of Life 63
44. Statement-I: Rudolf Virchow modified the hypothesis of Statement-II: Material to be packaged in the form of vesicle
Schleiden and Schwann to give the cell theory a final shape. from the ER fuse with trans face of the Golgi-apparatus.
Statement-II: Cell theory does not explain “how new cells
47. Statement-I: Nuclear pores are formed by the fusion of two
were formed”.
parallel membranes with perinuclear space.
45. Statement-I: Cell wall is present in all eukaryotic cell.
Statement-II: The nuclear pores are the passages through
Statement-II: Cell wall is always flexible and selectively
which movement of molecules take place bi-directionally.
permeable.
48. Statement-I: Ribosomes perform protein synthesis.
46. Statement-I: In cell, golgi apparatus remains in close
association with the ER. Statement-II: Ribosomes are membrane bound organelle.
NEET Past 10 Year Questions
1. Which of the following is an incorrect statement? (2021) 6. Which is the important site of formation of glycoproteins and
a. Microbodies are present both in plant and animal cells. glycolipids in eukaryotic cells? (2020)
b. The perinuclear space forms a barrier between the materials a. Peroxisomes b. Golgi bodies
present inside the nucleus and that of the cytoplasm. c. Polysomes d. Endoplasmic reticulum
c. Nuclear pores act as passages for proteins and RNA 7. The biosynthesis of ribosomal RNA occurs in: (2020-Covid)
molecules in both directions between nucleus and
a. Golgi apparatus b. Microbodies
cytoplasm.
d. Mature sieve tube elements possess a conspicuous nucleus c. Nucleolus d. Ribsosomes
and usual cytoplasmic organelles. 8. Inclusion bodies of blue-green, purple and green photosynthetic
bacteria are: (2020-Covid)
2. Match List- 1 with List- 2 (2021)
a. Gas vacuoles b. Centrioles
List- 1 List - 2
c. Microtubules d. Contractile vacuoles
A. Cristae (i) Primary constriction in
chromosome 9. Match the following columns and select the correct option:
B. Thylakoids (ii) Disc-shaped sacs in Golgi (2020-Covid)
apparatus
Column-I Column-II
C. Centromere (iii) Infoldings in mitochondria
1. Smooth Endoplasmic (i) Protein synthesis
D. Cisternae (iv) Flattened membranous sacs in Reticulum
stroma of plastids
2. Rough endoplasmic (ii) Lipid synthesis
Choose the correct answer from the options given below. reticulum
a. A-i B-iv C-iii D-ii 3. Golgi complex (iii) Glycosylation
b. A-iii B-iv C-i D-ii 4. Centriole (iv) Spindle formation
c. A-ii B-iii C-iv D-i
(1) (2) (3) (4)
d. A-iv B-iii C-ii D-i
a. (iii) (i) (ii) (iv)
3. When the centromere is situated in the middle of two equal b. (iv) (ii) (i) (iii)
arms of chromosomes, the chromosome is referred as: (2021) c. (i) (ii) (iii) (iv)
a. Telocentric b. Sub-metacentric d. (ii) (i) (iii) (iv)
c. Acrocentric d. Metacentric 10. The size of Pleuropneumonia - like Organism (PPLO) is:
4. The organelles that are included in the endomembrane system (2020-Covid)
are: (2021) a. 1 - 2 μm b. 10 - 20 μm
a. Endoplasmic reticulum, Golgi complex, Lysosomes and c. 0.1 μm d. 0.02 μm
Vacuoles. 11. The shorter and longer arms of a submetacentric chromosome
b. Golgi complex, Mitochondria, Ribosomes and Lysosomes. are referred to as (2019)
c. Golgi complex, Endoplasmic reticulum, Mitochondria and a. s-arm and l-arm respectively
Lysosomes. b. p-arm and q-arm respectively
d. Endoplasmic reticulum, Mitochondria, Ribosomes and c. q-arm and p-arm respectively
Lysosomes. d. m-arm and n-arm respectively
5. Which of the following statements about inclusion bodies is 12. Which of the following pair of organelles does not contain
incorrect? (2020) DNA? (2019)
a. These are involved in ingestion of food particles. a. Mitochondria and Lysosomes
b. They lie free in the cytoplasm b. Chloroplast and Vacuoles
c. These represent reserve material in cytoplasm c. Lysosomes and Vacuoles
d. They are not bound by any membrane d. Nuclear envelope and Mitochondria
Cell: The Unit of Life 65
13. Which of the following statements is not correct? (2019) 22. Which of the following cell organelles is responsible
a. Lysosomes have numerous hydrolytic enzymes. for extracting energy from carbohydrates to form ATP?
b. The hydrolytic enzymes of lysosomes are active under (2017-Delhi)
acidic pH. a. Lysosome b. Ribosome
c. Lysosomes are membrane bound structures. c. Chloroplast d. Mitochondrion
d. Lysosomes are formed by the process of packaging in the 23. Which of the following components provides sticky character
endoplasmic reticulum.
to the bacterial cell? (2017-Delhi)
14. The concept of “Omnis cellula-e cellula” regarding cell a. Cell wall b. Nuclear membrane
division was first proposed by (2019)
c. Plasma membrane d. Glycocalyx
a. Rudolf Virchow b. Theodor Schwann
c. Schleiden d. Aristotle 24. The correct sequence of involvement of cell organelles in
secretion of proteins from the cell is: (2017-Gujarat)
15. Which of the following statements regarding mitochondria is
incorrect? (2019)
a. Nucleus → Endoplasmic reticulum → Ribosomes → Golgi
apparatus → Secretory vesicles → Plasma membrane
a. Outer membrane is permeable to monomers of
carbohydrates, fats and proteins. b. Nucleus → Ribosomes → Endoplasmic reticulum → Golgi
b. Enzymes of electron transport are embedded in outer apparatus → Secretory vesicles → Plasma membrane
membrane. c. Nucleus → Ribosomes → Endoplasmic reticulum →
c. Inner membrane is convoluted with infoldings. Lysosomes → Plasma membrane
d. Mitochondrial matrix contains single circular DNA d. Nucleus → Endoplasmic reticulum → Ribosomes →
molecule and ribosomes. Golgi apparatus → Lysosomes → Plasma membrane
16. Which among the following is not a prokaryote? (2018) 25. Which of the following pathways is involved for packaging
a. Saccharomyces b. Mycobacterium of secretory proteins? (2017-Gujarat)
c. Nostoc d. Oscillatoria a. RER → Trans face of Golgi body → Cis face of Golgi
17. Which of the following is true for nucleolus? (2018) body → Secretory vesicles
a. Larger nucleoli are present in dividing cells. b. Trans face of Golgi body → Cis face of Golgi body →
b. It is a membrane-bound structure. RER → SER → Secretory veiscles
c. It takes part in spindle formation. c. RER → Cis face of Golgi body → Trans face of Golgi
d. It is a site for active ribosomal RNA synthesis body → Secretory vesicles
d. Cis face of Golgi body → Trans face of Golgi body →
18. The Golgi complex participates in (2018)
RER → Secretory vesides
a. Fatty acid breakdown
b. Formation of secretory vesicles 26. The type of ribosomes is same in (2017-Gujarat)
c. Respiration in bacteria a. Eukaryotic cytoplasm, mitochondria and endoplasmic
reticulum
d. Activation of amino acid
b. Cytoplasm of eukaryotic cells, their mitrochondria and
19. Which of the following events does not occur in rough
chloroplasts
endoplasmic reticulum? (2018)
a. Protein folding c. Cytoplasm of eukaryotic cells, their chloroplasts and
microbodies
b. Protein glycosylation
d. Prokaryotes, mitochondria and chloroplasts
c. Cleavage of signal peptide
d. Phospholipid synthesis 27. Reserved material in prokaryotic cells is stored as:
(2017-Gujarat)
20. Many ribosomes may associate with a single mRNA to form
multiple copies of a polypeptide simultaneously. Such strings a. Basal body b. Inclusion bodies
of ribosomes are termed as (2018) c. Mesosome d. Polysome
a. Polysome b. Polyhedral bodies 28. A complex of ribosomes attached to a single strand of mRNA
c. Plastidome d. Nucleosome is known as: (2017-Gujarat)
21. Select the incorrect match: (2018) a. Okazaki fragment b. Polymer
a. Lampbrush chromosomes – Diplotene bivalents c. Polyribosome d. Polypeptide
b. Allosomes – Sex chromosomes
29. A cell organelle containing hydrolytic enzymes is: (2016 - II)
c. Submetacentric – L-shaped chromosomes
chromosomes a. Ribosome b. Mesosome
d. Polytene chromosomes – Oocytes of amphibians c. Lysosome d. Microsome
66 Cell: The Unit of Life
30. Select the wrong statement: (2016 - II) 39. The structures that are formed by stacking of organized
a. Cyanobacteria lack flagellated cells. flattened membranous sacs in the chloroplasts are: (2015)
b. Mycoplasma is a wall-less microorganism a. Stroma lamellae b. Stroma
c. Bacterial cell wall is made up of peptidoglycan. c. Cristae d. Grana
d. Pilli and fimbriae are mainly involved in motility of 40. Nuclear envelope is a derivative of: (2015)
bacterial cells a. Microtubules
31. Select the mismatch: (2016 - II) b. Rough endoplasmic reticulum
a. Protists - Eukaryotes c. Smooth endoplasmic reticulum
b. Methanogens - Prokaryotes d. Membrane of Golgi complex
c. Gas vacuoles - Green bacteria 41. DNA is not present in: (2015)
d. Large central vacuoles - Animal cells a. Nucleus b. Mitochondria
32. A complex of ribosomes attached to a single strand of RNA is c. Chloroplast d. Ribosomes
known: (2016 - I) 42. Match the columns and identify the correct option. (2015 Re)
a. Polysome b. Polymer Column-I Column-II
c. Polypeptide d. Okazaki fragment A. Thylakoids (i) Disc-shaped sacs in Golgi
33. Microtubules are the constituents of: (2016 - I)
apparatus
a. Cilia, Flagella and Peroxisomes B. Cristae (ii) Condensed structure of DNA
b. Spindle fibres, Centrioles and Cilia C. Cisternae (iii) Flat membranous sacs in stroma
D. Chromatin (iv) Infoldings in mitochondria
c. Centrioles, Spindle fibres and Chromatin
d. Centrosome, Nucleosome and Centrioles a. A-(iii), B-(iv), C-(i), D-(ii)
34. Spindle fibres attach on to: (2016 - I) b. A-(iii), B-(i), C-(iv), D-(ii)
a. Telomere of the chromosome c. A-(iii), B-(iv), C-(ii), D-(i)
d. A-(iv), B-(iii), C-(i), D-(ii)
b. Kinetochore of the chromosome
c. Centromere of the chromosome 43. Cellular organelles with membranes are: (2015 Re)
d. Kinetosome of the chromosome a. Chromosomes, ribosomes and endoplasmic reticulum
b. Endoplasmic reticulum, ribosomes and nuclei
35. Mitochondria and chloroplast are
A. Semi-autonomous organelles c. Lysosomes, Golgi apparatus and mitochondria
B. Formed by division of pre-existing organelles and they d. Nuclei, ribosome and mitochondria
contain DNA but lack protein synthesizing machinery 44. Balbiani rings are sites of: (2015 Re)
Which one of the following options is correct? (2016 - I)
a. Nucleotide synthesis
a. Both (A) and (B) are correct b. Polysaccharide synthesis
b. (B) is true but (A) is false c. RNA and protein synthesis
c. (A) is true but (B) is false d. Lipid synthesis
d. Both (A) and (B) are false
45. Chromatophores take part in: (2015 Re)
36. Which one of the following is not an inclusion body found in a. Growth b. Movement
prokaryotes? (2015)
c. Respiration d. Photosynthesis
a. Glycogen granule b. Polysome
46. The structures that help some bacteria to attach to rocks and /
c. Phosphate granule d. Cyanophycean granule or host tissues are: (2015 Re)
37. The chromosomes in which centromere are situated close to a. Fimbriae b. Mesosomes
one end are: (2015) c. Holdfast d. Rhizoids
a. Telocentric b. Sub-metacentric
47. Which of the following structures is not found in a prokaryotic
c. Metacentric d. Acrocentric cell? (2015 Re)
38. Select the correct matching in the following pairs: (2015) a. Ribosome b. Mesosome
a. Rough ER – Synthesis of glycogen c. Plasma membrane d. Nuclear envelope
b. Rough ER – Oxidation of fatty acids 48. Which of the following is not membrane-bound? (2015 Re)
c. Smooth ER – Oxidation of phospholipids a. Ribosomes b. Lysosomes
d. Smooth ER – Synthesis of lipids c. Mesosomes d. Vacuoles
Cell: The Unit of Life 67
49. The motile bacteria are able to move by: (2014) 56. The Golgi complex plays a major role: (2013)
a. Pili b. Fimbriae a. In post translational modification of proteins and
c. Flagella d. Cilia glycosidation of lipids
b. In trapping the light and transforming it into chemical
50. The solid linear cytoskeleton elements having a diameter of 6
energy
nm and made up of a single type of monomer are known as:
c. In digesting proteins and carbohydrates
(2014)
d. As energy transferring organelles
a. Lamins b. Microtubules
57. Which one of the following cellular parts is correctly
c. Microfilaments d. Intermediate filaments
described? (2012 Mains)
51. The osmotic expansion of a cell kept in water is chiefly a. Thylakoids - flattened membranous sacs forming the grana
regulated by: (2014) of chloroplasts
a. Ribosomes b. Mitochondria b. Centrioles - sites for active RNA synthesis
c. Vacuoles d. Plastids c. Ribosomes - those on chloroplasts are larger (80S) while
52. Which structures perform the function of mitochondria in those in the cytoplasm are smaller (70S)
bacteria? (2014) d. Lysosomes - optimally active at a pH of about 8.5
a. Mesosomes b. Nucleoid 58. Which one of the following structures is an organelle within
an organelle? (2012 Mains)
c. Ribosomes d. Cell wall
a. Ribosome b. Peroxisome
53. Match the following and select the correct answer: (2014)
c. ER d. Mesosome
A. Centriole i. Infoldings in mitochondria
59. Select the correct statement from the following regarding cell
B. Chlorophyll ii. Thylakoids membrane: (2012 Pre)
C. Cristae iii. Nucleic acids
a. Fluid mosaic model of cell membrane was proposed by
D. Ribozymes iv. Basal body cilia or flagella Singer and Nicolson
a. A-iv B-iii C-i D-ii b. Na+ and K+ ions move across cell membrane by passive
b. A-iv B-ii C-i D-iii transport
c. A-i B-ii C-iv D-iii c. Proteins make up 60 to 70% of the cell membrane
d. A-i B-iii C-ii D-iv
d. Lipids are arranged in a bilayer with polar heads towards
54. Which one of the following organelle in the figure correctly the inner part
matches with its function? (2013)
60. What is true about ribosomes? (2012 Pre)
a. These are self-splicing introns of some RNAs
b. The prokaryotic ribosomes are 80S, where “S” stands for
sedimentation coefficient
c. These are composed of ribonucleic acid and proteins
d. These are found only in eukaryotic cells
61. Which one of the following does not differ in E.coli and
a. Rough endoplasmic reticulum, protein synthesis Chlamydomonas? (2012 Pre)
b. Rough endoplasmic reticulum, formation of a. Cell membrane
glycoproteins b. Ribosomes
c. Chromosomal Organisation
c. Golgi apparatus, protein synthesis
d. Cell wall
d. Golgi apparatus, formation of glycolipids
62. Ribosomal RNA is actively synthesised in:
55. A major site for synthesis of lipids is: (2013) (2012 Pre)
a. Nucleoplasm b. RER a. Ribosomes b. Lysosomes
c. SER d. Symplast c. Nucleolus d. Nucleoplasm
Answer Key
Topic-wise Questions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
d d a b d c d b d b d d a c a b c
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
d c d d d c b a b b d c c a a c a
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
d c d c c d d a a d c c d c c c a
52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
d a c d b a c c c b c c c b b c d
69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
a c c c c d b b d c d b d b d b a
86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
c c d d a a b a d d d b d c d a d
103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119
c a c a d c a c a a c b a d d c b
120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136
b d d c b a b a c d a b c b c a b
137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153
d a d a d c b c a a c b c b c b b
154 155 156 157 158 159 160 161 162 163 164
c c c a d d a b c d c
Morale Booster Questions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
b b d b c a a b c c a a c a d b a
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
d d b b d a b b a b a c b a d d c
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
d a c b c c d c c c b d a d d b b
52 53
a c
Multi-Concept Questions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
d b b d c a c c a c a d c a d a d
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
c b d d a b b a a b d b c d d c b
35 36 37 38 39 40 41 42 43 44 45 46 47 48
b c b c b a d c b a b c d c
NEET Past 10 Year Questions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
d b d a a b c a d c b c d a b a d
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
b d a d d d b c d b c c d d a b b
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
c b d d d b d a c c d a d a c c c
52 53 54 55 56 57 58 59 60 61 62
a b a c a d a a c a c
8-Cell: The Unit of Life
21. (d) Double membrane-bound organelles are mitochondria,
Topic-wise Questions
nucleus and chloroplast.
1. (d) 2. (d) 3. (a) 22. (d)
4. (b) Rudolf Virchow was the first person to explain that cells 23. (c) In prokaryotes, membrane bound organelles are is absent
divide and new cells are formed from pre-existing cell but ribosomes are present. They genetic material is naked.
(Omnis cellula a cellula).
24. (b) Bacteria is a prokaryotic cell. It lacks membrane bound
5. (d) Cell theory as understood today describes that nucleus and other organelles.
• All cells evolve from pre-existing cell.
25. (a) Both peroxisomes and lysosomes are bounded by single
• Body of animals and plants are composed of cell and its
membrane. Mitochontria is double-membrane bound
product.
structure.
The cellular component of plant and animal is quite same
but plant cell has three different components such as 26. (b) 27. (b) 28. (d)
vacuole, cell wall and chloroplast. 29. (c) Cells vary greatly in their shape. They may be disc-
6. (c) Statement (c) is incorrect as Matthias Schleiden was a like, polygonal, columnar, cuboid, thread like, or even
german botanist. irregular. Different shape of different cell:
• Mesophyll cell: Round and oval
7. (d) 8. (b) • WBC: Amoeboid
9. (d) Plasma or cell membrane is present in all cells. • Columnar epithelial cell:Long and narrow
• Tracheid:Elongated
10. (b) Well-defined nucleus is absent in prokaryotic cell.
30. (c) 31. (a)
11. (d)
Organism Size 32. (a) The four basic shapes of bacteria are bacillus (rod like),
Mycoplasm 0.3 µm coccus (spherical), vibrio (comma shaped) and spirillum
(spiral).
Bacteria 3-5 µm
In the question all the options are incorrect according to
RBC 7-8 µm the shape of bacteria except coccus (spherical).
Thus, the correct option is “d”.
33. (c) 34. (a)
12. (d) 35. (d) Prokaryotic cell wall is composed of peptidoglycan.
13. (a) The size of blood platelets are 2-3 μm in diameter but they 36. (c)
are considered to be fragment of cell rather than being an
37. (d) Many bacteria consist of small circular DNA outside the
individual cell. Thus, erythrocytes are considered as the
genomic DNA. These smaller DNA are called as plasmid.
smallest cell.
They are much smaller than nucleoid. The plasmid DNA
14. (c) Ostrich egg is the largest isolated single cell. confers certain unique phenotypic characters to such
15. (a) In the given statements, two statements are incorrect as bacteria. One such character is resistance to antibiotics.
follows: Therefore, all the options are correct with respect to
• Prokaryotes are generally smaller and multiply more plasmid.
rapidly than the eukaryotic cells
38. (c)
• Blue-green algae are an example of prokaryotes.
• Mesosome: They are infoldings of cell membrane in
16. (b) Membrane bound nucleus is absent in prokaryotic cell. prokaryotic cell.
• Plasmid: A plasmid is a double-stranded, circular DNA
17. (c) Mesosome is found only in prokaryotic cell.
molecule that is different from the chromosomal DNA of
18. (d) Cytosol or intracellular fluid or cytoplasmic matrix is a a cell.
jelly-like semifluid complex of cytoplasm. Both mesosome and plasmid, perform different function
19. (c) and are present in prokaryotic cell.
20. (d) Non-membranous organelles are nucleolus, ribosome and 39. (c) Mesosome is a membranous structure, which is formed
centriole. by the extension of cell membrane into the cell. These
Cell: The Unit of Life 39
extensions are present in the form of vesicles, tubules 58. (c) 59. (c)
and lamellae. They help in cell wall formation, DNA 60. (c) Lipids, proteins and carbohydrates are present in the cell
replication, etc, they also help in respiration and secretion membrane.
processes and increases the surface area of the plasma
membrane and enzymatic content. They are present in 61. (b)
prokaryotes only. 62. (c) The ratio of protein and lipid differs from one cell to
40. (d) Membranous extension into the cytoplasm called another. In humans, the membrane of the RBCs has
chromatophores containing pigments are present in some approximately 40 per cent lipids and 52 per cent proteins.
prokaryotes such as cyanobacteria. 63. (c)
41. (d) Flagella of bacteria is made up of three parts namely— 64. (c) On the basis of ease of extraction, membrane proteins can
filament, hook and basal body. be categorized as integral and peripheral proteins.
42. (a) The longest part of the bacterial flagella which extends 65. (b) The quasifluid nature of lipid allows lateral movement of
from the surface of cell to the outside is known as filament. protein within the bilayer of a cell membrane.
43. (a) Pili are surface structures of the bacteria but do not 66. (b) Components of membranes such as proteins, glycolipids,
play any role in motility. The pili are elongated tubular and glycoproteins, are distributed asymmetrically.
structures made up of a special protein (pilin). They are 67. (c) Intrinsic proteins are found embedded in phospholipid
present in gram negative bacteria only. They help in bilayer.
mating process. Therefore, the correct option is (d).
68. (d) The fluid nature of the membrane is important to perform
44. (d) Small bristle-like fibres present on the bacterial cell functions like cell division, cell growth, secretion and
surface are referred to as fimbriae. endocytosis, formation of intercellular junctions.
45. (c) Prokaryotic ribosomes are made of two subunits 30 S and 69. (a) Facilitated transport is the movement of substances along
50 S, which when present together form 70 S. the concentration gradient without using energy via
46. (c) Larger and smaller subunit of prokaryotic ribosome is 50 specific carrier proteins.
S and 30 S respectively. 70. (c) Both facilitated and active transport diffusion is mediated
47. (d) Polysome or polyribosome is formed by the attachment of via membrane protein (intrinsic or extrinsic protein)
ribsosomes to single mRNA. that changes their conformation during the process of
48. (c) diffusion. However, simple diffusion doesn’t require any
carrier protein for the transport of molecules.
49. (c) Gas vacuoles are found in green, blue and purple
photosynthetic bacteria. 71. (c) A polar molecule cannot pass through the non-polar lipid
bilayer or we can say that lipid bilayer is impermeable.
50. (c) Nostoc is a prokaryote therefore 70S type of ribosomes
are present. 72. (c) The chemical nature of carrier molecules facilitating
transport across plasma membrane is proteinaceous.
51. (a) Animal cell lacks chloroplast. Chloroplast performs
photosynthesis in plants. 73. (c) Different molecules or ions move across the membrane
against their concentration gradient, from lower to higher
52. (d) Plant cells have a cell membrane as well as a cell wall
concentration. Active transport is an energy-dependent
whereas; animal cells only have a cell membrane. Cell
process that utilizes ATP, for example, Na+/K+ Pump.
wall helps in maintaining the shape and rigidity of the
cell. Animal cell do not have cell wall because: 74. (d) Cell wall of algae is composed of cellulose, galactans,
• They consist of muscles and nerves mannans and minerals.
• They do not have any fixed shape 75. (b) In higher plants, the cell wall is composed of cellulose,
• They can move their body pectin, hemicellulose and proteins.
• They have to change the size of their body during
locomotion
76. (b) The cell envelope of bacteria constitutes three layers
namely glycocalyx, cell wall and cell membrane.
53. (a) 54. (c) 55. (d) Glycocalyx- It is the outermost mucilage layer of the cell
56. (b) Plasma membrane or the cell membrane is the barrier envelope.
between protoplasm and outer environment in an animal Cell Wall- It is rigid outer covering, which maintains
cell. shape and provide structural support to the cell. It lies
57. (a) The lipid bilayer prevents the passage of ions and large between plasma membrane and glycocalyx.
polar molecules across the membrane. Thus, the lipid Plasma/cell membrane-It forms the innermost layer of
membrane acts as a barrier of polar molecules. cell envelope.
40 Cell: The Unit of Life
77. (d) Secondary wall is present nearest to plasma membrane. • It is cylindrical or sausage-shaped having a diameter of
0.2-1.0 µm.
78. (c) The secondary wall is formed inner to the cell membrane
• It is a double membrane-bound structure with the outer
of the plant cell.
membrane and the inner membrane dividing its lumen
79. (d) The secondary cell wall is a structure present between the distinctly into two aqueous compartments.
primary cell wall and the plasma membrane in many plant
104. (a)
cells. The primary wall (the cell wall of a young plant cell)
is capable of growth, which gradually diminishes as the 105. (c) Mitochondria is called the powerhouse of the cell because
cell matures and the secondary wall is formed on the inner it is responsible for production of energy.
(towards membrane) side of the cell. Therefore, statement 106. (a)
(d) is incorrect.
107. (d) As the bulk of the reactions and synthesis of energy in the
80. (b) form of ATP take place in mitochondria, it is also known
81. (d) Cell wall perform various functions such as it provide as powerhouse of the cell.
shape and protects the cell from the mechanical damage 108. (c)
and infection, helps in cell-to-cell interaction and act as
109. (a) Respiratory enzymes associated with the process of
barrier to undesirable macromolecules.
cellular respiration such as oxidase, dehydrogenase, or
82. (b) Plasmodesmata helps in connecting the cytoplasm of catalase are present in the mitochondria.
neighbouring cells middle lamella glues the different
neighbouring cell together. 110. (c) The process of oxidative phosphorylation occurs in the
mitochondria. Thus, mitochondria consist of oxidative
83. (d) The outer membrane of the nucleus is continuous with enzyme.
ER, so the space between the inner and outer nuclear
membrane is directly connected with the lumen of ER. 111. (a) Mitochondrion is a double membrane -bound structure in
which outer membrane separates the mitochondrial core
84. (b) Endoplasmic reticulum is an interconnected membranous
from surrounding.
network of the cell which consists of vesicles, flattened
sacs and tubules. 112. (a)
85. (a) 113. (c) Mitochondria is a double membrane-bound organelle
with the outer membrane and the inner membrane. The
86. (c) The smooth endoplasmic reticulum is the major site for
outer membrane forms the continuous limiting boundary
synthesis of lipid.
of the organelle. The inner membrane forms a number of
87. (c) infoldings called the cristae towards the matrix. The two
88. (d) Endoplasmic reticulum helps in the modification membranes have their own specific enzymes associated
and transportation of newly formed proteins to their with the mitochondrial function. Both the membranes of
destination. mitochondria are structurally and functionally different.
89. (d) The main function of sphaerosomes is to aid in lipid 114. (b) F0-F1 particles also called oxysomes are small particles
metabolism. These are also called plant lysosomes. In projecting from inner surfaces of cristae and inner
animal cells, smooth endoplasmic reticulum helps in mitochondrial membrane.
synthesis of lipids. 115. (a) Mitochondria take part in cellular respiration in which
90. (a) 91. (a) 92. (b) 93. (a) • Oxygen is used to breakdown the glucose and release CO2
and water.
94. (d) 95. (d) 96. (d)
• ATP is generated by using ADP through oxidative
97. (b) Lysosome contains hydrolytic enzymes. phosphorylation in which water is released as bi-product.
98. (d) 99. (c) 100. (d) 116. (d) Mitochondria is known as power house of the cell because
101. (a) In Amoeba, the contractile vacuole is important for it acts as site of ATP production.
osmoregulation. 117. (d) 118. (c) 119. (b)
102. (d) Vacuole is a membrane-bound organelle. Which consists 120. (b) The number of chloroplast differs from 1 per cell in
of water, sap, excretory product, and other non-cellular Chlamydomonas to 20 to 40 per cell in the mesophyll cell
materials. In plant cells, 90% volume of the cell is of leaves.
occupied by vacuole.
121. (d) 122. (d)
103. (c) Characteristic features of mitochondria are:
123. (c) Plastid involved in storage of fat is known as elaioplast.
• It is not easily visible under the microscope unless
specifically stained. 124. (b) 125. (a) 126. (b)
Cell: The Unit of Life 41
127. (a) Chloroplasts of the green plants are found mostly in the 156. (c)
mesophyll cells. 157. (a) In acrocentric chromosome, the centromere is present
128. (c) close to its end where one arm is very long and other is
129. (d) Chromoplasts are developed from proplastids, leucoplasts very short.
and chloroplasts. Transformation of chloroplasts is 158. (d) Nucleus is a dense membrane bound structure in cell
observed during ripening of fruit (e.g., tomato, chilli) however; nucleus is not present in each and every cell. It
when they change their colour from green to reddish is absent in the sieve tubes (plant cells). Sieve tubes cells
orange. are conducting cells that lack a nucleus and ribosomes.
130. (a) Extra chromosomal DNA is found in organelles like Also, matureRBCs lack nucleus or DNA.
mitochondria and chloroplast. 159. (d) The nuclear matrix or the nucleoplasm contains nucleolus
131. (b) 132. (c) 133. (b) and chromatin.
134. (c) Thylakoids are arranged in stacks like the piles of coins 160. (a) 161. (b)
called grana or the intergranal thylakoids. 162. (c) 163. (d)
135. (a) 136. (b) 164. (c) Microbodies are membrane bound small vesicles which
137. (d) Chromatin, ribosome and virus are the nucleoprotein consist of different enzymes and are found in both plant
structures. and animal cells.
138. (a) Lysosome helps in breaking complex macromolecules
Morale Booster Questions
139. (d) Sedimentation coefficient(s) indirectly is a measure of
size and density is indirectly mesured.. 1. (b) Photorespiration is a plant metabolic process in which
140. (a) Ribosomes are associated with synthesis of proteins. In three organelles namely chloroplasts, peroxisomes, and
animal cells, protein synthesis takes place on ribosomes mitochondria are involved. Therefore, option (B) is
found in cytoplasm and mitochondria. correct.
141. (d) 142. (c) 2. (b) Plastids are present in all plant cells and euglenoids. They
can divide into different forms depending on the cells
143. (b) Here, statements D and E are correct. Only cilia works requirement because all plastids have the same structure.
like an oar. Also, flagella are comparatively longer and
responsible for cell movement. The prokaryotic bacteria 3. (d) Ribosomes are not bounded by membrane and they play
also possess flagella but they are structurally different an important role in protein synthesis. Thus, the statement
from that of the eukaryotic flagella saying that ribosomes is not involved in protein synthesis is
wrong.
144. (c) Cilia and flagella emerge from centriole-like structure
known as basal body. 4. (b) In the given options, Anabaena is the only organism
which is not an eukaryotic and only possess prokaryotic
145. (a) characteristic, i.e., absence of membrane-bound organelles
146. (a) During nuclear division, centriole is important in the and nucleus.
formation of spindle apparatus. 5. (c) In prokaryotic cells (mycoplasma, blue-green algae, and
147. (c) A centrosome is an organelle that consists of two cylindrical bacteria), the Golgi apparatus or Golgi complex is absent.
structures referred to as centrioles. In centrosome, the It is present in all eukaryotic cells except plant sieve tubes,
centrioles place perpendicular to each other in which each bryophyte,pteridophyte sperm, and mammalian red blood
has an organization like the cartwheel. They are made up corpuscles.
of nine evenly spaced peripheral fibrils of tubulin protein.
6. (a) Satellite is a small chromosomal segment apart from the
Therefore, statements (B) and (C) are incorrect.
main body of the chromosome separated by a secondary
148. (b) 149. (c) constriction. In humans, it is usually associated with the
150. (b) Centrioles and centrosomes are found in the animals cells. short arm of an acrocentric chromosome. They play an
important role in the formation of the nucleolus after the
151. (c)
process of cell division. Chromosomes number 13, 14, 15,
152. (b) Statement (c) is false because plasmids are self-replicating 21 and 22 are examples of SAT (satellite) chromosomes.
extra chromosomal segments of double-stranded circular
7. (a) Cells in an organism differs greatly in their size, shape and
DNA.
volume.
153. (b) 154. (c) I. Smallest cell is mycoplasmas with size only 0.3 μm.
155. (c) Nucleolus is responsible for the synthesis of ribosomes. II. Size of bacterial cell is 3 - 5 μm.
42 Cell: The Unit of Life
III. Human red blood cells are of about 7.0 µm in diameter. center of phosphorylation is oxysomes. It is present
IV. Ostrich eggs are among the largest cell with size inside the cristae of the mitochondria. They are generally
(15 × 13) cm. involved in ATP synthesis and are also referred to as fo-f1
particles. Therefore, they are referred to as a functional
8. (b) A mitochondrion is a membrane-bound structure having unit of mitochondria.
two aqueous compartments, the outer compartment and
the inner compartment. 17. (a) Prokaryotic cells are the only one to which consist of
• The outer membrane forms the continuous limiting mesosomes.
boundary of the organelle. 18. (d) The cell envelope consists of a tightly bound three layers,
• The inner membrane forms several infolding referred to i.e., the outermost glycocalyx followed by the cell wall
as the cristae towards the matrix. The cristae enhance the and then the plasma membrane.
surface area.
19. (d) All the functions written are performed by Golgi
The two membranes have their specific enzymes
apparatus.
associated with mitochondrial function. Therefore, both
the inner and outer membrane of mitochondria is different The Golgi apparatus is an organelle found in most
from each other structurally and functionally. eukaryotic cells. Golgi apparatus is an important site of
formation and packaging of glycoproteins and glycolipids.
9. (c) Singer and Nicolson (1972) put forward the fluid mosaic
model of cell membrane which states that plasma membrane 20. (b) Cristae are formed as a result of infoldings of the inner
is made up of lipid bilayer and quasi fluid nature of liipds mitochondrial membrane.
helps in the movement of proteins within the cell membrane.
21. (b) A centromere is a confined area of a chromosome that
10. (c) In plant cell, the vacuole is bound by unit membrane known divides it into two arms; short arm and a long arm. The
as tonoplast. The tonoplast helps in the transport of ions and centromere holds two chromatids of a chromosome. The
other material against the concentration gradient into the chromosomes can be divided into four categories based
vacuole. Therefore, their concentration is high as compared on the position of the centromere.
to the cytoplasm.
22. (d) Inclusion bodies are not bounded by membrane. They
11. (a) Cell wall that is composed of peptidoglycan is present in are concerned with storage of reserve food materials, like
bacteria and not in eukaryotes. The cell wall of eukaryotes cyanophycean granules, etc.
is made up of cellulose, hemicellulose, pectin, chitin etc.
23. (a) In acentric chromosome,centromere is absent.
12. (a) Lysosomes are membrane-bound vesicular structures formed
24. (b) A channel protein is a type of transport protein that acts
by the process of packaging in the Golgi apparatus. They
like a pore in the membrane to allow water molecules or
comprise of different types of hydrolytic enzymes such as
small ions to pass through it quickly.
lipase, carbohydrases, and protease that are active at low
pH (acidic). They can easily digest carbohydrates, proteins, 25. (b) Phosphoglycerides are present in lipid part of cell
lipids, and nucleic acids. If a lysosome ruptures within a cell, membrane.
cell death (autolysis) occurs and the entire cell, including 26. (a) Lysosomes are single membrane bound vesicular
the cell organelles is digested because of the presence of the structures. It is formed during the process of packing of
hydrolytic enzyme. proteins in the Golgi apparatus.
13. (c) Presence of thylakoids, mark the difference between 27. (b) The chloroplasts consist of chlorophyll and carotenoid
chloroplast, and mitochondria. Thylakoids are flattened pigments which are responsible for trapping light energy
sacs like structure that contains chlorophyll which help in essential for photosynthesis. Chlorophyll pigment is
photosynthesis. present in the grana of the chloroplast.
14. (a) Cytoskeleton is not associated with functions 28. (a) Lysosomal vesicles are rich in hydrolytic enzymes-such
like intracellular transport. The microtubules and as proteases, lipases and carbohydrases.
microfilaments are a part of cytoskeleton and are
29. (c) The axoneme has nine pairs of doublets of radially
responsible for cellular and intercellular movements.
arranged peripheral microtubules, and a pair of centrally
15. (d) A single nucleosome is made up of around 150 base pairs located microtubules. Such an arrangement of axonemal
of DNA wrapped around a core of histone proteins. The microtubules is referred to as the 9 + 2 array.
nucleosomes are organized together like beads. They are 30. (b) Most chloroplasts of the green plants are present in the
repeatedly folded to make a chromosome. Therefore, the mesophyll cells of the leaves. These are lens-shaped,
nucleosome consists of histones. spherical, oval, discoid or even ribbon-like organelles
16. (b) A mitochondrion is a cell organelle where different having variable length (5-10µm) and width (2-4µm). In
oxidative-phosphorylation reaction takes place. The higher plants, they are lens shaped.
Cell: The Unit of Life 43
31. (a) Endoplasmic reticulum produces lysosomal enzymes, 41. (d) The matrix of mitochondria has single circular DNA
which are packaged within the vesicles of the Golgi molecule, a few molecules of RNA, ribosomes (70S) and
apparatus. These vesicles then buds off from the Golgi other structures required for the production of proteins.
complex leading to the formation of lysosome. Therefore,
42. (c) Membrane proteins are of two types: integral and
the correct sequence is:
peripheral. Integral proteins are partially or totally buried
Endoplasmic Reticulum → Golgi complex →Lysosomes
in the membrane while peripheral proteins lie on the
32. (d) All three possess the ability to multiply by process such as surface of membrane.
fision. 43. (c) Matrix and cristae found in cell organelle called
33. (d) The typical flow of membrane within the cell is follow; mitochondria
From nuclear envelope (B) to rough ER (A), then from 44. (c) According to fluid mosaic model (proposed by Singer
rough ER (A) to Golgi apparatus (C), and from Golgi
& Nicolson), plasma membrane is composed of
apparatus (C) to the cell membrane (E). Membrane
phospholipids, extrinsic protein and intrinsic protein.
movement between nuclear envelope, Golgi appartus, and
ER is through veiscles (D). 45. (b) The plasma membrane is composed of lipid bilayer,
extrinsic and intrinsic proteins. The movement of lipid
34. (c) The nucleosome is the most basic component of
molecules from one lipid monolayer to another monolayer
chromatin. Each nucleosome is composed of a histone
is called flip-flop movement. Flip-flop movement is
octamer, which is made up of DNA wrapped around a set
rarely found in lipid molecules whereas it remain absent
of eight proteins called histones. Therefore, the correct
in protein molecules.
option is (c) that is nucleosome (d).
46. (d) Golgi apparatus is an important site of production of
35. (d) The given features depict cell organelle - vacuole. Vacuole
is a unit membrane bound, found in both animal and plant glycoproteins and glycolipids. Of all the post-translational
cells but are much larger in plant cells. They are enclosed modifications, phosphorylation (addition of phosphate
space, filled with water containing inorganic and organic group) and glycosylation (addition of saccharide) are the
molecules which includes enzymes in solution. Though major players in many of the protein functions.
in some cases they may contain solids which have been 47. (a) Turgor pressure act as limiting factor for osmosis, and
engulfed. They might store food or variety of nutrients once a cell becomes turgid, no more water may be taken
that a cell might need to survive. They can even store on.
waste products to protect the cell from infections.
48. (d) Diffusion may occur in either direction across a membrane
36. (a) The concept of membrane fluidity refer to the fact that and always along the concentration gradient. The larger
both lipids and proteins can show lateral movement within the gradient, the faster diffusion will occur.
the bilayer. In cold weather, the fluidity of membranes in
49. (d) Plastids are found exclusively in plants cell.
a plants can be maintained by increasing the number of
phospholipids with unsaturated hydrocarbon tails. 50. (b) Prokaryotes lack membrane-bound organelles. They
possess the ability to survive in high salinity and
37. (c) Chromosome consists of the genetic material (DNA) that temperature.
helps in the transmission of hereditary character from one
51. (b) The pellet is undergoing cellular respiration i.e.,
generation to another.
production of ATP. It occurs in mitochondria.
38. (b) The cell wall protects the cell, maintains its shape and
52. (a) The statements which are consistent with the scientist’s
provides supports and strength to it. Nucleus controls the
observation are:
cell’s activities. Chloroplast is a cell organelle that makes
A. The toxin was stored in the central vacuole
food for the plant cell. The cell membrane holds the parts
of the cell together and also separates the cell from its B. The toxin can caross the palsma membrane but not the
surroundings. membrane of the organelle in which it is stored
39. (c) Presence and absence of ribosome, divides ER into two E. The toxin may be an enzyme.
types namely RER and SER. RER is involved in synthesis 53. (c) Many proteins must be deposited into the ER lumen
of proteins and SER helps in lipid synthesis. (membranous sacs) as they are made. Some of these are
40. (c) Mitochondria are the sites of aerobic respiration. They to be secreted out of the cell and must start their journey
forms cellular energy in the form of ATP. Therefore, they in the ER: others are simply too dangerous to synthesize
are known as ‘power house’ of the cell. In absence of in the cell’s cytoplasm (cytosol), such as lysosomal
oxygen, respiration will not take place hence mitochondria hydrolases that would digest away parts of the cell if
will be absent. allowed to freely float around the cell after synthesis.
44 Cell: The Unit of Life
nutrients that a cell might need to survive. They can even
Multi-Concept Questions
store waste products in order to protect rest of cell from
1. (d) contamination.
Osmosis and passive Without use of energy 28. (d) The incorrect statement is (d) because ribosomes are 70s
transport type.
Active transport Utilization of energy 29. (b) The main arena of cellular activities in both plant and
molecules like ATP.
animal cells is the cytoplasm.
2. (b) Protein synthesis occurs in ribosomes, which are attached
30. (c) Plant cells contain smaller Golgi body like vesicles, which
to surface of E.R. About 50 hydrolytic enzymes are
are known as dictyosomes. The centrioles are absent in
present in the lysosome such as proteases, nucleases,
plant cell.
glycosidases, lipases, phospholipases, phosphatases and
sulphatases. All enzymes are acid hydrolases and are 31. (d) Microbodies are membrane-bound minute vesicular
active at pH-5.0. organelles. They are found in both plant and animal
cells. They contain various enzymes and proteins, but not
3. (b) 4. (d)
genetic material.
5. (c) SER is involved in synthesis & storage of glycogen in
skeletal muscle and liver cells. 32. (d)
6. (a) 7. (c) 8. (c) 9. (a) 33. (c) The content of nucleolus is continuous with the
nucleoplasm as it is not a bounded by membrane. In
10. (c) 11. (a) 12. (d)
the chromoplasts, fat soluble carotenoid pigments like
13. (c) Pair A is true. carotene, xanthophylls and others are found. The axoneme
Centrioles – It is made up of tubulin protein. has nine pairs of doublets of radially arranged peripheral
Lysosomes – It consist of hydrolytic enzymes. microtubules, and a pair of centrally located microtubules.
Amyloplasts – They are responsible for the synthesis and Such an arrangement of axonemal microtubules is known
storage of starch granules. as the 9+2 array.
Elaioplasts – It stores fats and oil. 34. (b) The cell envelope of bacteria is made up of three layer
Aleuroplasts – It stores proteins. i.e., the outermost glycocalyx followed by the cell wall
and then the cell membrane. Convex side of golgi body is
14. (a) Chloroplasts have a highly permeable outer membrane; a
called forming face.
much less permeable inner membrane, in which membrane
transport proteins are embedded. 35. (b) In an animal cells, centrioles are present which are absent
in almost all plant cells.
15. (d) 16. (a)
36. (c) Mitochondria and chloroplast both are considered as sites
17. (d) The rate of simple diffusion of a solute always increases
of production of cellular energy. They contain circular
directly proportional to the with solute concentration.
naked DNA, RNA and 70S ribosomes.
Thus, it increases with solute concentration.
37. (b) An Amoeba engulfs its prey by forming pseudopodia
18. (c) 19. (b) 20. (d)
and a part of the cell membrane cut off to form a food
21. (d) Glycolysis occurs in cytoplasm vacuole inside the cell. The vacuole fuses with lysosome,
22. (a) NCERT (XI) Ch - 8, Pg. 131, Fig. 8.4 a membranous sac containing hydrolytic enymes, that
23. (b) NCERT (XI) Ch - 8, Pg. 128, Fig. 8.2 digest the prey. The resulting small food molecules are
absorbed into the cytoplasm.
24. (b) Rough Endoplasmic Reticulum (RER) are found in the
cells that are actively synthesizing and secreting protein 38. (c) Process like diffusion and osmosis are not mutually
exclusive and can take place at the same time.
25. (a) In bacterial cell 70s type ribosomes are found.
39. (b) Cell membrane show quasifluid behavior that enables
26. (a) When group of ribsome binds to an mRNA molecules is
lateral movement of proteins within the bilayer.
called polysome. Golgi apparatus is the important site of
formation of glycoproteins and glycolipids. 40. (a) According to the functions, cell possess different structure.
Some are round, some are biconcave. Some have nucleus
27. (b) Vacuole is a membrane bound organelle, present in both
while some are enucleated.
animal and plant cells but are large in plant cell. Vacuoles
are enclosed compartments that are filled with water 41. (d) Inner foldings of inner membrane of mitochondria is called
containing organic and inorganic molecules including cristae which increases the surface area of membrane
certain enzymes in solution. Vacuoles might store food or toward the matrix.
Cell: The Unit of Life 45
42. (c) Nucleoli are prominent in cells actively carrying out Every chromosome essentially has a primary constriction
protein synthesis because it is a site for active ribosomal or the centromere. Centromere holds two chromatids of a
RNA synthesis. chromosome.
43. (b) Mesosomes performs the same function as mitochondria Cisternae are flat, disc-shaped sacs stacked parallel to
does. In eukaryotes, they are said to be analogous each other in Golgi apparatus.
to mitochondria. They are the invaginations of cell 3. (d) NCERT (XI) Ch - 8, Pg. 139
membrane found in bacteria. Metacentric – Centromere is present in the middle thus
forming two equal arms of the chromosome.
44. (a) Rudolf Virchow (1855) explained that cells divide and
new cells are formed from pre-existing cells. Schleiden Sub-metacentric – Centromere is located slightly away
from the middle of the chromosome resulting into one
and Schwann proposed that all living organisms are
shorter arm and one longer arm.
composed of cells and products of cells. This cell theory
given by Schleiden and Schwann did not explain how new Acrocentric – Centromere is situated near to the end of the
cells are formed. So, Rudolf Virchow modified this theory chromosome leading to the formation of one extremely
to new one. short arm and one very long arm.
Telocentric – Centromere is present at the terminal end of
45. (b) In eukaryotes, cell wall is present in fungi and plants
the chromosome.
only. Fungal cell wall is composed of chitin, a structural
homoglycan and plant cell wall has cellulose as a major 4. (a) NCERT (XI) Ch - 8, Pg. 133
constituent. Cell wall can be tough, flexible and sometimes Endoplasmic reticulum, Golgi complex, Lysosomes
rigid. and vacuoles are included in endomembrane system
46. (c) The pathway involves secretion of protein is as follows: because their functions are coordinated. Mitochondria
RER→Golgi apparatus → secretory vesicles→ plasma is semi-autonomous cell organelle and ribosome is non-
membrane membranous cell organelle.
So, Golgi apparatus remains in close association with 5. (a) NCERT (XI) Ch - 8, Pg. 129
ER for protein synthesis. RER would fuse to Golgi in Reserve material in prokaryotic cells are stored in the
form of vesicles and there undergo further modification cytoplasm in the form of inclusion bodies. These are
and packaging. Materials to be packaged in the form of not bound by any membrane system and lie free in the
vesicles from ER fuses with the cis or forming face of cytoplasm.
golgi apparatus & moves towards the trans or maturing
Lysosomes are involved in ingestion of food particle.
face.
6. (b) NCERT (XI) Ch - 8, Pg. 134
47. (d) Nuclear envelope is interrupted by minute pores,
Golgi bodies are the important site of formation of
called nuclear pores, formed by fusion of two nuclear
glycoproteins and glycolipids.
membranes. Through these pores, materials (RNA,
protein) are transported into or out of the nucleus. 7. (c) NCERT (XI), Ch - 8, Pg. 138
48. (c) Ribosomes plays a very important role in protein synthesis Nucelolus is a site for active ribosomal RNA synthesis.
but it is not membrane bound. There are free ribosomes in Larger and more numerous nucleoli are present in cells
cell. actively carrying out protein synthesis.
8. (a) NCERT (XI), Ch - 8, Pg. 129
NEET Past 10 Year Questions Reserve material in prokaryotic cells are stored in the
cytoplasm in the form of inclusion bodies. These are
1. (d) NCERT (XI) Ch - 8, Pg. 138 & 140 and Ch - 6, Pg. 88 not bound by any membrane system and lie free in the
Microbodies are membrane bound minute vesicles that cytoplasm, e.g., phosphate granules, cyanophycean
contain various enzymes and are present in both plant and granules and glycogen granules. Gas vacuoles are found in
animal cells. blue green and purple and green photosynthetic bacteria.
Mature sieve tube elements have peripheral cytoplasm 9. (d) NCERT (XI), Ch - 8, Pg. 133, 134, 138
and large vacuole. The nucleus is absent in it.
The smooth endoplasmic reticulum is the major site for
2. (b) NCERT (XI) Ch - 8, Pg. 133, 135, 138, 139 synthesis of lipid. In animal cells lipid-like steroidal
The inner membrane of mitochondria forms a number of hormones are synthesised in SER.
infoldings called the cristae towards the matrix. RER is frequently observed in the cells actively involved
Thylakoids are organized flattened membranous sacs in protein synthesis and secretion. They are extensive and
present in the stroma of chloroplasts. continuous with the outer membrane of the nucleus.
46 Cell: The Unit of Life
Golgi apparatus is the important site of formation of 23. (d) NCERT (XI) Ch - 8, Pg. 128
glycoproteins and glycolipids. Sticky character of the bacterial wall is due to glycocalyx
The centrioles form the basal body of cilia or flagella, and or slime layer. This layer is rich in glycoproteins.
spindle fibres that give rise to spindle apparatus during 24. (b) The correct sequence of involvement of the cell organelles
cell division in animal cells. in secretion of proteins from the cell is Nucleus →
Ribosomes → Endoplasmic reticulum → Golgi apparatus
10. (c) NCERT (XI), Ch - 8, Pg. 128, fig. 8.2
→ Secretory vesicles → Plasma membrane.
The prokaryotic cells are represented by bacteria, blue-
25. (c) NCERT (XI) Ch - 8, Pg. 134
green algae, mycoplasma and PPLO (Pleuro Pneumonia
Like Organisms). The size of PPLO is 0.1 µm. Materials to be packaged in the form of vesicles from
the RER fuse with the cis face of the Golgi apparatus
11. (b) NCERT (XI) Ch - 8
and move towards the maturing face and then they are
Shorter arm and longer arm of chromosome is designated released from its trans face.
as ‘p’ arm (p = petite i.e. short) and ‘q’ arm respectively.
26. (d) NCERT (XI) Ch - 8, Pg. 134-136
12. (c) NCERT (XI) Ch - 8, Pg. 135-136
The mitochondrial, chloroplast and prokaryotic ribosomes
Lysosomes and vacuoles do not contain DNA.
are 70S.
13. (d) NCERT (XI) Ch - 8, Pg. 134
Lysosomes bud off from trans face of Golgi bodies. 27. (b) NCERT (XI) Ch - 8, Pg. 129
Precursor of lysosomal enzymes are synthesised by RER Reserve material in prokaryotic cells is stored in the
and then send to Golgi bodies for further processing. cytoplasm in the form of inclusion bodies.
14. (a) NCERT (XI) Ch - 8, Pg. 126 28. (c) NCERT (XI) Ch - 8, Pg. 129
The concept of “Omnis cellula-e cellula” regarding cell In the cytoplasm, several ribosomes attach to a single
theory was first proposed by Rudolf Virchow. strand of mRNA, forming a structure known as a
15. (b) NCERT (XI) Ch - 8, Pg. 135 polyribosome or polysome.
In mitochondria, enzymes for electron transport are 29. (c) NCERT (XI) Ch - 8, Pg. 134
embedded in the inner membrane. The isolated lysosomal vesicles have been found to
16. (a) Saccharomyces is a genus of yeast. be very rich in almost all types of hydrolytic enzymes
17. (d) NCERT (XI) Ch - 8, Pg. 138 (hydrolases – lipases, proteases, carbohydrases) optimally
Nucleolus is a small dense spherical structure in nucleus active at the acidic pH.
of cell. It is the site of ribosome biosynthesis. 30. (d) NCERT (XI) Ch - 8, Pg. 129
18. (b) NCERT (XI) Ch - 8, Pg. 134 The pili are elongated tubular structures made of a special
Golgi complex (apparatus) is a packaging organelle like protein. The fimbriae are small bristle like fibres sprouting
ER. It modifies the proteins and lipids from ER and out of the cell. In some bacteria, they are known to help
concentrate them and packs them into secretory vesicles. attach the bacteria to rocks in streams and also to the host
tissues but they do not play a role in motility.
19. (d) NCERT (XI) Ch - 8, Pg. 133
Phospholipid synthesis occurs in the cystosol adjacent 31. (d) NCERT (XI) Ch - 8, Pg. 129
to ER membrane. In smooth endoplasmic reticulum, Plant and animal cells are different as plant cells
phospholipids are synthesised from phosphatidic acid and possess cell walls, plastids and a large central vacuole
1, 2 - diacylglycerol. which are absent in animal cells. On the other hand,
animal cells have centrioles which are absent in almost
20. (a) NCERT (XI) Ch - 8, Pg. 129
all plant cells.
Polysome or polyribosome is a cluster of ribosomes held
together by a strand of mRNA. 32. (a) NCERT (XI) Ch - 8, Pg. 129
Ribosomes are the site of protein synthesis. Several
21. (d) NCERT (XI) Ch - 8, Pg. 139
ribosomes may attach to a single mRNA and form a chain
Polytene chromosomes are present in salivary glands of called polyribosomes or polysome.
Dipteran larvae.
22. (d) NCERT (XI) Ch - 8, Pg. 135 33. (b) NCERT (XI) Ch - 8, Pg. 137
Mitochondria is the site of aerobic oxidation of Microtubules are the constituents of spindle fibres,
carbohydrates to generate ATP. centrioles and cilia.
Cell: The Unit of Life 47
34. (b) NCERT (XI) Ch - 8, Pg. 139 45. (d) NCERT (XI) Ch - 8, Pg. 129
Spindle fibres attach on to kinetochore of the In some prokaryotes like cyanobacteria, there are other
chromosome membranous extensions besides mesosomes, into
35. (c) NCERT (XI) Ch - 8, Pg. 135 the cytoplasm called chromatophores which contain
Mitochondria and chloroplast both are semi-autonomous photosynthetic pigments.
organelles and both contains single circular DNA, a few 46. (a) NCERT (XI) Ch - 8, Pg. 129
RNA molecules, ribosomes (70S) and the components
The fimbriae are small bristle like fibers sprouting out
required for the synthesis of proteins.
of the cell. They are known to help in attachment of the
36. (b) NCERT (XI) Ch - 8, Pg. 129 bacteria to rocks in streams and also to the host tissues.
Reserve material in prokaryotic cells are stored
47. (d) NCERT (XI) Ch - 8, Pg. 127
in the cytoplasm in the form of inclusion bodies,
e.g., phosphate granules, glycogen granules and Prokaryotic cells do not have membrane bound organelles.
cyanophycean granules. They lack a membrane bound nucleus.
37. (d) NCERT (XI) Ch - 8, Pg. 139 48. (a) NCERT (XI) Ch - 8, Pg. 133
In acrocentric chromosomes, the centromere is situated Ribosome’s are the granular structures mainly composed
close to its ends forming one extremely short and one very of RNA and proteins. They are not surrounded by any
long arm. membrane.
38. (d) NCERT (XI) Ch - 8, Pg. 133 49. (c) NCERT (XI) Ch - 8, Pg. 129
RER - Synthesis of protein.
Flagella aids motility. While pili and fimbriae do not play
SER - Synthesis of lipid and steroidal hormones. a role in motility.
39. (d) NCERT (XI) Ch - 8, Pg. 136 50. (c) Microfilament has a diameter of 5-7 nm and made up of
A number of organised flattened membranous sacs called single monomer.
the thylakoids, are present in the stroma. Thylakoids are
51. (c) NCERT (XI) Ch - 8, Pg. 134
arranged in stacks like piles of coins called grana.
Vacuoles are meant for osmoregulation.
40. (b) NCERT (XI) Ch - 8, Pg. 138
Nucleus is a double membrane bound organelle. Its 52. (a) NCERT (XI) Ch - 8, Pg. 128
outer membrane usually remains continuous with the Mesosome helps in respiration in prokaryotes analogous
endoplasmic reticulum bearing ribosomes. to mitochondria.
41. (d) NCERT (XI) Ch - 8, Pg. 136 53. (b) NCERT (XI) Ch - 8, Pg. 137
Except ribosomes, nucleus, chloroplast and mitochondria
Centriole - Basal body cilia on flagella
have DNA. Ribosomes are composed of ribonucleic
acid (RNA) and proteins and are not surrounded by any Chlorophyll - Thylakoid
membrane.
Cristae - Infoldings in mitochondria
42. (a) NCERT (XI) Ch - 8, Pg. 133, 135 and 136
Ribozymes - Nucleic acid
In chloroplasts, a number of organised flattened
membranous sacs called the thylakoids, are present in 54. (a) NCERT (XI) Ch - 8, Pg. 133
the stroma. The inner mitochondrial membrane forms SER: Ribosome absent, involved in lipid synthesis
a number of infoldings called the cristae towards the
matrix. Golgi bodies consists of many flat, disc-shaped RER: Ribosome present, involved in protein synthesis
sacs or cisternae, stacked parallel to each other, of 0.5 µm 55. (c) NCERT (XI) Ch - 8, Pg. 133
to 1.0 µm diameter.
SER is the site for lipid synthesis.
43. (c) NCERT (XI) Ch - 8, Pg. 136
56. (a) NCERT (XI) Ch - 8, Pg. 134
Ribosomes are the granular structures first observed by
Major role in post translational modification of protein
George Palade (1953). They are not surrounded by any
and glycosidation of lipids. It also help in packaging.
membrane.
57. (a) NCERT (XI) Ch - 8, Pg. 135
44. (c) Polytene chromosomes first seen in salivary gland of
Centriole - Helps in cell division
Chironomus tantans. They show puff or balbiani rings
which develops lateral loops where DNA becomes active Nucleolus - Sites for active RNA synthesis
and produce copies of RNA. Lysosome - Acidic pH
48 Cell: The Unit of Life
58. (a) NCERT (XI) Ch - 8, Pg. 126 Na+ and K+ ions move across cell membrane by active
Ribosome is found within two organelles - chloroplasts transport.
(in plants) and mitochondria. 60. (c) NCERT (XI) Ch - 8, Pg. 129
59. (a) NCERT (XI) Ch - 8, Pg. 132 Ribosomes are non-membrane bound organelles found
in all cells – both eukaryotic as well as prokaryotic. In
The detailed structure of the membrane was studied only
prokaryotes, ribosomes are associated with the plasma
after the advent of the electron microscope in the 1950s.
membrane of the cell. They are about 15 nm by 20 nm
An improved model of the structure of cell membrane was
in size and are made of two subunits - 50S and 30S units
proposed by Singer and Nicolson (1972) widely accepted which when present together form 70S prokaryotic
as fluid mosaic model. ribosomes. Ribosomes are the site of protein synthesis.
In human beings, the membrane of the erythrocyte Ribosomes are composed of ribonucleic acid and
has approximately 52 per cent protein and 40 per cent proteins
lipids. 61. (a) Cell membrane of prokaryotes is structurally similar to
The lipids are arranged within the membrane with the that of eukaryotes. So, it does not differ in E.coli and
polar head towards the outer sides and the hydrophobic Chlamydomonas.
tails towards the inner part. This ensures that the nonpolar 62. (c) NCERT XI Ch - 8, Pg. 138
tail of saturated hydrocarbons is protected from the Ribosomes are the site of protein synthesis. Nucleolus is a
aqueous environment. site of active ribosomal RNA synthesis.
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