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membrane-bound sacs, and contain powerful oxidative enzymes. Their chief
function is to remove toxic substances.

attached to the rough endoplasmic reticulum. Ribosomes contain RNA


the spindle during cell division.

the membrane. It is in the mitochondria that the sugar is finally burnt during
these compounds and for mechanical work.
Structure of mitochondria
Plastids: These organelles are found only in plant cells.
Plastids are of three types
Chloroplasts :

presence of chlorophyll. Chromoplasts


They are colourless and found in roots, seeds and underground stems.


Chromoplasts impart colour to flowers to attract insects for pollination.

The nucleus is composed of the following structures:
Nuclear Membrane
Chromatin network

Structure of a nucleus

Nuclear membrane:
cytoplasm. The nuclear membrane has minute pores which allow the
selective transfer of material between the nucleoplasm and the cytoplasm.

chromatin network lie suspended in the nucleoplasm.

Nucleolus: This dense, spherical granule found in the nucleus contains RNA

Chromatin network:
transmitting hereditary characteristics from one generation to another. A gene is
A Typical Animal Cell:

A Typical Plant Cell

A Generalised Animal Cell as observed under an Electron Microscope.

Endoplasmic Reticulum (ER)
types of endoplasmic reticula are seen -
Tubes with a smooth surface are called smooth endoplasmic reticula. They
secrete lipids.
Tubes with spherical bodies (ribosomes) attached are known as rough
endoplasmic reticula.

enzymes secreted by the cell.

Golgi Apparatus


along with some vacuoles and clusters of vesicles. The function of the Golgi Body
peroxisomes. The Golgi body is usually found close to the nucleus.

Their main function is digestion. They contain powerful destructive enzymes
Lysosomes present in white blood cells are capable of digesting bacteria and

membrane-bound sacs, and contain powerful oxidative enzymes.
Their chief function is to remove toxic substances.
Discovery of Cell Robert Hooke at first examining a thin slice of dead cork [the
bark of a tree] through a self-designed microscope in 1665. Robert Hooke predicts
boxes. He called these boxes cells. He described about this in his book

Cell is a Latin word which means ‘a little room’. The word cell was derived from a
Greek word “Cellulae” which means small room. First living cell was discovered by
A.V. Leeuwenhoek with the improved microscope in pond water.
Q. What are Living Organisms made up of?
Answer: All living organisms that we observe around us are made up of cells.

Q. Who gave the cell theory? What does it state? Which organism is an
exception of cell theory?
Answer: Two biologists, “Schleiden and Schwann” gave the “Cell theory” which
was later on expanded by “Rudolf Virchow”. Cell theory states that
(a) All plants and animals are composed of cells. (b) Cell is the basic unit of life. (c)
All cells arise from pre-existing cells. Viruses are the exceptions of cell theory.Þ


(a) New cells are formed from pre-existing cells.

(b) Movement of water molecules from their higher concentration to their

lowerconcentration through a semi- permeable membrane is called Osmosis.
(c) The functional components of cell are plasma membrane, cytoplasm &

(d) Protoplasm has two parts- cytoplasm & nucleoplasm.

(e) Nucleus, mitochondria & plastids have their own DNA & ribosomes.

(f) The shrinkage or contraction of the contents of the cell away from the cell wall
is known as plasmolysis.

(g) The process by which Amoeba can engulf a food particle is endocytosis.

(h) Biogenesis is the manufacture of lipids required for making cell membrane.

(i) A cell that lacks nuclear membrane is called a prokaryotic cell & the nuclear
region is called nucleoid.

(j) Movement of materials in & out of the cell takes place by diffusion & osmosis.

2. What is the advantage of multicellularity over unicellularity?

Ans- Division of labour.

3. What are the chromosomes made up of?

Ans- DNA & proteins

cell to swell up.

5. Why are lysosomes known as “suicidal bags”?

damaged cell

6.Why is the nucleus so significant in a cell?

Ans- Nucleus has the following important functions-
(i) It controls all cell activities
generation to the next(iii) It helps in cell division

7. Differentiate between plant and animal cells.

3- Do not possess lysosomes.
4- Nucleus is towards the periphery.
5- Centrioles are absent

1- Surrounded only by cell / plasma membrane.
2-Do not possess plastids.
3-Possess lysosomes
4-Nucleus is in the center ..
5-Centrioles present & help in cell division.

8. Give the major functions of the following cell organelles-

has ribosomes attached to it SER- Synthesis of lipids required for making
cell membrane
a source of energy.
(d) Ribosomes ---Protein synthesis
(e) Golgi ApparatusStorage & packaging of various products.
(f) LysosomesDigestion of worn out & damaged organelles

Q. Why do we put peel off the skin of onion (called epidermis) immediately in a
watch-glass containing water?
Answer: This will help to keep peel wet.

Q. All cells come from pre-existing cells .Justify?

Answer: All organisms around are made up of cells. There are single cells
organism called unicellular like amoeba where as some single body are made up
of many cells called multi-cellular organism. Cells divide to produce cells of their
own kind. Hence, all cells come from pre-existing cells.

Q. What are the types of cell on the basis of type of organization?

Answer: (i) Prokaryotic cells: Cells having less developed nucleus without nuclear
membrane and nucleolus. E.g. Bacteria. These are primitive and incomplete cells.

(ii) Eukaryotic cells: Cells having well developed nucleus with unclear membrane
and nucleolus. e.g. Plants and animals.

Q. How do all cells look alike in terms of shape and size?

Answer: Cells are of variable shapes and sizes. Their shape is according to the
function. Generally cells are spherical but they may be long and branched(nerve
cell), Kidney shaped (guard cell in plant’s leaves), discoidal (RBC), spindle shaped
(muscle cell) etc.
Size of cell varies from 0.2 mm to18 cm in diameter. Some are microscopic while
some are visible with naked eyes.
For example:

Þ Size of a typical cell in a Multicellular organism ranges from 20-30 mn.

Þ The largest cell is ostrich egg (15 cm. in diameter with shell & 8 cm. in diameter
without shell)

Þ The longest cell is nerve cell. (up to 1m. or more) and Red Blood cells are the
smallest cell in our body.

Þ Smallest cells so far known are PPLOs e.g. mycoplasma (0.1mm in diameter.)

Þ Human egg is 0.1 mm. in diameter.

Þ Unicellular alga, Acetabularia is about 10cm long.

Q. How does a living cell perform basic functions?

Answer: a living cell perform basic functions by division of labour among specific
components within it known as cell organelles.

In Text:

1. Who discovered cells, and how?

Answer: Robert Hooke at first examining a thin slice of dead cork [the bark of a
tree] through a self-designed microscope in 1665 and discovered cell.

2. Why is cell called the structural and functional unit of life?

Answer: All living things are made up of small structures called cells. Cells also
perform all the basic functions in all living things. This is why cell is called the
structural and functional unit of life.

Q. What is a cell made up of?

Answer: A cell is made up of plasma membrane, nucleus and cytoplasm

Q. What is the function of plasma membrane?

Answer: plasma membrane is the outermost covering of the cell present in both
plants [below the cell wall] and animal cell.
Singer and Nicholson gave the fluid mosaic model of plasma membrane according
to him it consists of a protein layer between two layers of lipids.

(a) It separates the contents of the cell from its external environment.

(b) It allows the entry and exit of some materials in and out of the cell.

Q. How does the movement of substances take place into the cell?
Answer: Some substances like carbon dioxide or oxygen can move across the cell
membrane by a process of diffusion whereas water can move across the cell
membrane by a process of osmosis.

Q. What are diffusion and osmosis?

Answer: Diffusion is a spontaneous movement of a substance from a region of
high concentration to a region to a region of concentration is low through a
selectively permeable membrane.
The movement of water molecules through a selectively permeable membrane
is called osmosis. Therefore, osmosis is a special case of diffusion through a
selectively permeable membrane.

Q. How do substances move out of the cell?

Answer: As there is a difference of concentration of CO2 inside and outside a cell,
low concentration outside the cell by the process of diffusion.

Q. What will happen if we put an animal cell or a plant cell into a solution of
sugar or salt in water?
Answer: The cell swell up as the cell will gain water by osmosis. This happens
because the concentration of the solution outside the cell is lesser than that of
cytoplasm of cell.

Q. What are isotonic solution, hypertonic solution and hypotonic solutions?

Answer: Types of solution on the basis of concentration:

(A)Isotonic solution: When the concentration of the solution outside the equal to
the Concentration of cytoplasm of the cell it is called as isotonic solution.

(B) Hypertonic solution: When the f concentration of the solution outside the cell
is more than that inside the cell. Due to this cell looses water and becomes

(C) Hypotonic solution: When the concentration of the solution outside the cell is
lesser than that of cytoplasm of cell. Due to this cell swells up and bursts.

Q. Remove the shell of an egg by dissolving it into dilute hydrochloric acid. Put
the egg in pure water and left it for 5 minutes. What do we observe?
Answer: The egg swells because the cell will gain water by osmosis. This happens
because the medium surrounding the cell has a higher water concentration than
the cell

Q. When we put dried raisins or apricots in plain water and leave them for some
time they swell. Why?
Answer: Each dried raisins or apricots gains water by osmosis and swells when
placed in water.
independent existence.


semi permeable membrane and selectively permeable membrane?
called a selectively permeable membrane.

Ans: Mature erythrocytes don't have mitochondria

Q.What are plastids? Write their functions?

2. Chloroplasts provide colored to various flowering parts.
3. Leucoplasts help in storage of protein, starch and oil


Ans: Centrioles.

Q. Name two semi- autonomous organelles?

Ans: Chloroplast and mitochondria

Q. Which cell organelle is rich in acid hydrolases?

Ans: Lysomes are loaded with acid hydrolases

Q. Which cell organelles are called ribonucleoprotine particle?

Ans: Ribosome.

Q. Differentiate between SER and RER

as ribosomes are concerned with protein synthesis.
lipid synthesis in intestinal cells and with steroid formation in adrenals

Q. what is the difference between eukaryotes and prokaryotes?

Prokaryotes Eukaryotes
They are mainly multicellular except for
They are mainly unicellular
They have only a few organelles Many organelles
DNA is circular DNA is linear
DNA lies in the cytoplasm (Nucleus
DNA is inside the nucleus
Cell division occurs mostly through binary
Mitosis, meiosis or both take place.

Q .What is the difference between osmosis and diffusion.

Osmosis Diffusion
It is the movement of water. It is the movement of solute particle.
Membrane is required Membrane is not required.
Movement from low concentration to Movement from high concentration to
high concentration of solute. low concentration of solute.
It is associated with liquids. It is associated with both liquid and

Q. Where are peroxisomes found ?

involved in photorespiration in plants.

Ans: 1. Cytoplasm- Reactions of glycolysis.
2. Mitochondria- Reactions of Kreb's cycle.
3. Nucleoplasm- Reactions involving formation of RNA.

Q. what is Diffusion?
lower concentration. So, it is a type of diffusion.

Q . What is dictyosomes ?
Ans: Dictyosomes are membranous or vesicular structures making up the Golgi
apparatus. They together with golgi vesicles form the golgi apparatus .

Q. Which tissue protects the entire body?

Answer: Epithelial tissue

Q.Give one example each of:

Answer1. Squamous epithelium (simple) - cheek cells
2. Columnar epithelium - intestine

Q.Give one example of connective tissue in which matrix is solid?

Answer : Bone

Q. Name the following:

Ans: 1. Multinucleate muscle fibre: - skeletal muscle fibre

2. Spindle shaped muscle fibre: - smooth muscle fibre

3. Tissue which stores fats: - adipose

4. Process of neuron, which carries impulse: -axon

Q.Name one structure in your body, which bears ciliated epithelium.

Answer: Respiratory tract

Q.What is aerenchyma?

Ans: It is a specialized parenchyma found in aquatic plants which

consists of network of small cells that enclose air cavities.
Q.What is the difference between simple plant tissue and simple
animal tissue?

1. Consists of same type of Cells. Consists of one or more types

of Cells.
2. Arrangement varies. Arranged in a single layer.

Q.What is the utility of tissues in multicellular organisms?

Answer: 1.Division of labour 2. Higher organization 3. Higher survival

Q.What is a synapse

Answer: Junction between two neurons.

Q.Where is apical meristem found?

Answer: Root and stem tips

Q. Identify the type of tissue in the following?

Answer: 1. Skin - epithelial 2. Bark - cork 3. Bone - connective

4. Lining of kidney tubules - epithelial 5. Vascular bundle - xylem and
Q. What is the role of epidermis?

Answer: a. Protection b. Regulates transpiration C. Exchange of

Q.What will happen if apical meristem is damaged?

Ans:Growth in length will stop.

Q.What are the components of phloem?

Ans:1. Phloem parenchyma 2. Phloem fibres 3. Sieve tubes 4.

Companion cells
Q.Name all simple plant tissues?

Ans:1. Parenchyma 2. Collenchyma 3. Sclerenchyma


(a)Nerve cell (b) Muscle cell (c)Liver cell (d)Kidney cell

(a)Cell wall (b) Nuclear membrane (c) Tonoplast (d) Plasma membrane


(a)Leeuwenhoek (b) Robert hooke (c) Flemming (d) Robert Brown

Q.4: Who proposed the cell theory? -

(a)Schleiden and Schwann (b) Watson and Crick (c) Darwin and Wallace (d) Mendel
and Morgan

Q.5: A plant cell differs from an animal cell in the absence of -

(a)Endoplasmic Reticulum (b) Mitochondria (c) Ribosome (d) Centrioles
Q.6: Centrosome is found in -
(a)Cytoplasm (b) Nucleus (c) Chromosomes (d) Nucleolus

Q.7: The power house of a cell is -

(a)Chloroplast (b) Mitochondrion (c) Golgi apparatus (d) Nucleolus


(a)Ribosome (b) Golgi apparatus ( c) Mitochondrion (d) Endoplasmic Reticulum

Q.9: Which is called ‘Suicidal Bag’?

(a)Centrosome (b) Lysosome (c) Mesosome (d) Chromosome

Q.10: Ribosomes are the center for -

(a)Respiration (b) Photosynthesis (c) Protein synthesis (d) Fat synthesis

Q.11: Double membrane is absent in -

(a)Mitochondrion (b) Chloroplast (c) Nucleus (d) Lysosome

Q.12: Cell organelle found only in Plant is -

(a)Golgi apparatus (b) Mitochondria (c) Plastids (d) Ribosomes


(a)Diploids (b) Prokaryotes (c) Haploids (d) Eukaryotes

Q.14: Animal cell is limited by -

(a)Plasma membrane (b) Shell membrane (c) Cell wall (d)Basement membrane


a)Nucleus (b) Nucleolus (c)Cytoplasm (d)Chromosomes

Q.16: Lysosome are reservoirs of -

(a)Fat (b) RNA (c) Secretary Glycoprotein (d) Hydrolytic Enzymes


(a)Tonoplast (b) Plasma membrane (c)Nuclear membrane (d)Cell wall

Q.18: Cell secretion is done by -

(a)Plastids (b) ER (c)Golgi apparatus (d)Nucleolus

Q.19: Centrioles are associated with -

(a)DNA synthesis (b) Reproduction (c)Spindle formation (d)Respiration
(a)Chromosome (b) Ribosome (c)Lysosome (d) Endoplasmic Reticulum



Q.22: Plasmolysis occurs due to -

(a)Absorption (b ) Endosmosis (c)Osmosis (d)Exosmosis

Q.23: A plant cell becomes turgid due to -

(a)Plasmolysis (b) Exosmosis (c) Endosmosis (d) Electrolysis


(a)Hypotonic (b) Isotonic (c) Hypertonic (d) None of the above

Q.25: A cell placed in hypertonic solution will -

(a)Shrink (b) Show Plasmolysis (c) Swell up (d) No change in shape or size

(a)AMP (b) ADP (c)ATP (d)APP
(a)Ribosome (b) Nucleus (c) Chloroplast (d)Mitochondria

Q.28: Root hair absorbs water from soil through -

(a)Osmosis (b) Active transport (c) Diffusion (d)Endocytosis


(a)2 (b)3 (c)4 (d)1

in London by -
(a)Robert Hooke (b) Robert Brown (c) Strasburger (d)Dujardin

Q.31: Cell inclusions are -

(a)Non-living materials present in the cytoplasm (b) Another name of cell organelle
(c) Cytoskeletal framework of cell (d) Combined name for cell wall and plasma


(a)Ribosome (b) Lysosome (c)ER (d)Nucleus


(a)Nucleus (b) Chloroplast (c)Mitochondrion (d)All of the above

Q.34: Cristae and Oxysomes are associated with -

(a)Mitochondria (b) Plastids (c)Golgi apparatus (d)Plasma membrane
Q.35: Karyotheca is another name of -
(a)Nuclear envelope (b) Nucleus (c)Nuclear pores (d)Nucleolus

(a) Golgi apparatus (b) Nucleus (c) Mitochondria (d) ER

Q.37: Plastids are present in -

(a)Animal cell only (b) Plant cells only
(c)Both animal cells and Plant cells (d)Neither animal nor plant cell


(a)Hemicellulose (b) Cellulose (c)Phospholipids (d)Proteins

Q.39: Intercellular connections of plant cells are called -

(a)Middle lamella (b)Micro fibrils (c)Matrix (d)Plasmodesmata

Q.40: Genes are located on the -

(a)Chromosomes (b)Nucleolus (c)Nuclear membrane (d)Plasma membrane

Q.41: Chromatin consists of -

(a)RNA (b) DNA (c)RNA and histones (proteins) (d)DNA and histones (proteins)


following separating the two arms -
(a)Centromere (b) Genes (c) Spindle (d)Nucleus


(a)Diffusion (b) Osmosis (c) Active transport (d)Plasmolysis