Download The fundamental units of life

TOPPER’S COACHING CENTRE
BIOLOGY
CH- 5
BELGAUM
CLASS -IX
The Fundamental Unit Of Life
IMPORTANT TERMS:Cell is the structural and functional unit of life.
Robert Hook discovered the cell in 1665.
Cells are enclosed by the plasma membrane formed of lipids and protein.
Protoplasm: It is the living material of the cell Purkinje coined the term
protoplasm.
Prokaryotic cell lack well organised nuclear membrane and membrane
bound organelles.
Eukaryotic cell have proper nucleus and membrane bound organelles.
Lysosomes are electron- microscopic vesicular structure of animal cell.
TERMS TO MEMORISE:Prokaryotes: The simple organism called Monerans without proper nucleus.
Nucleiod: A primitive nucleus of prokaryotic, not covered by nuclear
membrane.
Eukaryotes: - Organisms with true nucleus.
Cyclosis: - Streaming movement of cytoplasm.
Autolysis: - Self digestion of cell by its lysosomes enzymes.
Autophagy: - Digestion of its own cell organelles or reserve food by the
lysosomes.
Chloroplast: - Chlorophyll contains green coloured photosynthesis plastids.
Chromoplast: - A pigmented plastid.
Tonoplast:- Vacuolar membrane present around cell sap.
Q1) Who discovered cell and how?
Ans) Robert hook discovered cell in 1665. He examined the thin slices of cork
under the microscope. He observed the structure of honey comb consisting of
many compartment and called this boxes “cell”.
Q2) Why cell is called structural and functional unit of life?
Ans) Cells are arranged in proper and systematic order to perform a body of living
organisms. Thus cells serve as basic building structure unit for more complex
organisms. Cells are also functional unit of life because all the metabolic activities
of the body take place at cell level.
Q3) Name any two prokaryotic cells.
Ans) 1.Bacterial cells.
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2. Blue green algae.
Q4) Give six examples of single called organisms.
Ans) Paramecium, Amoeba, Chlamydomonas, Euglena, Trypanosoma and Malarial
parasite.
Q5) what are multicellular organisms.
Ans) The organisms formed of large number of cells are called multicellular
organisms.
Q6) Which is the smallest measuring unit in the field of the cell biology?
Ans) Angstrom (A).
Q7) What is nucleoid?
Ans) It is incipient nucleus of prokaryotes (bacteria and blue-green algae cells) and
is without nuclear membrane.
Q8) Differentiate between Prokaryotic and Eukaryotic cell.
Ans)
Prokaryotic cell
Eukaryotic cell
 Size generally small (1 Size is large 5-100nm.
-6
10nm) =10 m
 Nuclear
region
is
 Nuclear region is well defined
undefined due to absence
and surrounded by nuclear
of nuclear membrane and
membrane.
known as nucleoid.
 A chromosome is single.
 More than one.
Q9) Why lysosomes are called suicidal bags?
Ans) Lysosomes contains hydrolytic enzymes and these enzymes may digest their
own content. And cell would die. Thus, they are called suicidal bag.
Q10) which organelle is known as the power house of the cell? Why?
Ans) ‘Mitochondria’ is known as the power house of the cell. They are site for
synthesis, storage and transport of ATP commonly called energy currency.
Q11) What is osmosis?
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Ans) It is special case of diffusion through a selectively permeable membrane. It is
passage of water from a region of higher concentration to lower concentration.
Q12) Name three functional regions of the cell?
Ans) Plasma membrane, Nucleus, Cytoplasm.
Q13) Define plasmolysis?
Ans) Loss of water from a plant cell resulting in shrinkage or contraction of cell
away from cell wall.
Q14) What are the factors which restrict size of the cell?
Ans) The factors which restrict the size of the cell are:1. Function of the cell.
2. Cell’s requirement of oxygen and other material from environment.
3. Regulating ability of the nucleus of the cell.
Q15) Name three type of plastids?
Ans) The tree type of plastids are Leucoplasts, chloroplasts and Chromoplasts.
Q16) Distinguish between cell wall and cell membrane.
Ans)
Cell wall
Cell membrane
 Present in plant cell.
 It occurs in animal and
plant cell.
 Dead in nature.
 Living membrane.
 Composed of cellulose.
 Composed of lipids and
proteins.
Q17) Write functions of cell wall?
Ans) Functions of cell wall are:1) It provides shape and rigidity to the cell.
2) It provides the protoplast.
3) It increases the size of the cell by continuous absorption.
4) Growth of cell wall determines the growth of the cell.
Q18) List two function of centrosome.
Ans) Function of centrosome:1) They help in spindle formation during cell division in animal cell.
2) They act as basal bodies and give rise to motile structure cilia and flagella.
Q19) what are function of lysosomes?
Ans) function of lysosomes:-
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1) Take part in intercellular digestion of foreign particle.
2) They provide energy during starvation.
3) They help in defence against bacterial and viral infection.
Q20) List two function of vacuoles?
Ans) function of vacuole:1) They help the cell to remain turgid.
2) Vacuoles play important role in growth.
Q21) Differentiate between rough endoplasmic reticulum and smooth
endoplasmic reticulum?
Ans)
SER
RER
 It does not bear ribosome
 It
possesses
ribosome
over the surface of its
attached to its membrane
membrane which is smooth.
which is rough.
 It is engaged in the
 The reticulum takes part in
synthetic of glycogen, lipids
the synthesis of protein and
and steroids.
enzymes.
 It
gives
rise
to
 It help in formation of
sphaerosomes.
lysosomes through Golgi
apparatus.
Q22) what is function of vacuoles in plant cell?
Ans) Vacuoles are full of cell sap and provides rigidity and turgidity to the cell.
Q23) what happens to the cell if nucleus is removed?
Ans) Cell will die with the passage of time as nucleus is controlling centre of all
function of the cell.
Q24) What is diffusion?
Ans) The movement of a substance from a region of higher concentration to the
region of lower concentration.
Q25) where are proteins synthesised inside the cell?
Ans) Protein are synthesised on the ribosomes which are attached to the surface
of RER or lie freely in cytoplasm. Ribosomes are also called “protein factories” of
the cell.
Q26) Name two organelles which contains their own genetic material?
Ans) 1. Chloroplast.
2.Mitochondria.
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Q27) Give the function of plasma membrane?
Ans) Functions of plasma membrane are:1) It maintains the individuality of the cell.
2) It provides shape to the cell.
3) It protect cell from the injury.
4) It forms organelles of cell.
Q28) Write functions of Chromoplast?
Ans) Functions of Chromoplasts are:1) Chromoplasts are the sites of the photosynthesis.
2) Chromoplasts provides colour to the flower and fruit.
3) They are site of storage of food.
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