This post contains all the main and important topics which have complete and detailed solutions of Chapter 5 the fundamental unit of life .These solutions are based on the latest Rajasthan Board syllabus and prescribe NCERT book.
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Board |
RBSE |
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Subject |
Science |
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Chapter |
The fundamental unit of life |
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No. of End exercise questions |
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Prescribed Book |
NCERT Science |
The Fundamental Unit of Life Questions- Answer
Intext Questions
Answers of Questions on Page 51
Q.1 Who discovered
cell, and how?
Ans.
Robert Hooke (1165) discovered the cell.
He examined a fine slice of a cork under a self-manufactured primitive
microscope. He observed that the slice of cork resembled the structure of a
honey comb. These were actually dead cell walls observed by Robert Hooke. He
named these tiny compartment cellulae now termed cells.
Q.2 Why is the cell called the structural and functional
unit of life?
Ans.
Cell is the structural unit of life because;
all living organisms are made up of cells. Cell is functional unit of life
because functions of life like nutrition, respiration, excretion and reproduction
etc. are performed by cell only.
Answers of Questions on Page 53
Q.1 How do substances like CO2 and water move in and out of the cell? Discuss.
Ans.
Carbon dioxide (CO2) moves in
and out of the cells by the process of diffusion. In this movement particles
of various substances move from the region of the higher concentration to the
region of the lower concentration.
Water moves in and out of the cells by osmosis.
This is the movement of water from the region of its higher
concentration to the region of its lower concentration through a semi-permeable
membrane.
Q.2 Why is plasma membrane called a selectively permeable
membrane?
Ans.
Plasma membrane allows the movement of
only selected molecules across it, so it is called selectively permeable
membrane. For example, It allows the entry of gases through diffusion and water
through osmosis. Larger molecules may pass through the plasma membrane by an
active process. Plasma membrane is impermeable to certain other materials.
That’s why, it is selectively permeable.
Answers of Questions on Page 55
Answers of Questions on Page 57
Q.1 Can you name the two organelles, we have studied that
contain their own genetic material?
Ans.
Yes, mitochondria and chloroplast.
Q.2 If the
organisation of a cell is destroyed due to some physical or chemical influence,
what will happen?
Ans.
If organisation is destroyed or plasma
membrane is disturbed the cell would not be able to maintain the internal
environment and chemical uniqueness. It will lead to death of the cell,
Lysosomes would cause autolysis of the cell.
Q.3 Why are lysosomes known as suicide bags?
Ans.
Lysosomes are membrane-bound sacs which
contain hydrolytic enzymes. If lysosomes burst, enzymes are released and digest
other organelles of the same cell. Therefore, they are known as ‘suicide bags’.
Q.4 Where are proteins synthesised inside the cell?
Ans.
Proteins are synthesized over the
ribosomes.
Answers of End Exercise Questions on Page 59
Q.1 Make a comparison and write down ways in which plant
cells are different from animal cells.
Ans.
Q.2 How is a prokaryotic cell different from a eukaryotic
cell?
Ans.
Q.3 What would happen if the plasma membrane ruptures or breaks down?
Ans.
If plasma membrane is ruptures or break
down, the cell would not be able to maintain the internal environment and
chemical uniqueness. It will lead to death of the cell. Lysosomes would causes
autolysis of the cell.
Q.4 What would happen to the life of a cell if there was no
Golgi apparatus?
Ans.
Golgi apparatus packages and dispatch
enzymes, hormones and other necessary lipids and proteins secreted by ER to
target inside and outside of the cell.
The digestive enzymes which remain
concealed in lysosome will remain free in the cytoplasm killing the other cell
organelles. So in absence of Golgi apparatus cell would die.
Q.5 Which organelle is known as the powerhouse of the cell?
Why?
Ans.
Mitochondria are known as the powerhouse
of the cell because the energy required for various life activities is released
by mitochondria in the form of ATP molecule. Mitochondria contain enzymes that
are needed for oxidation of food present in the cells to CO2 and
water. Oxidation of food releases energy which is used to form high energy ATP
molecules. ATP is known as energy currency of the cell and these are used as
cellular fuel.
Q.6 Where do the lipids and proteins constituting the cell
membrane get synthesized?
Ans.
Proteins are synthesized over ribosomes
which are attached to rough endoplasmic reticulum while lipids are synthesized
over smooth endoplasmic reticulum.
Q.7 How does an Amoeba obtain its food?
Ans.
Amoeba is unicellular organism. It
acquires its food by the process of endocytosis. Plasma
membrane of Amoeba is flexible which helps it to engulf food particles. Phagosome
combines with lysosome to produce digestive or food vacuole. Digestion occurs
in food vacuole. The digested food passes into surrounding cytoplasm. The
undigested residue is thrown out of the cell.
Q.8 What is osmosis?
Ans.
Osmosis:
Osmosis is the process of Diffusion of water from the region of its higher
concentration (pure water or dilute solution) to the region of its lower
concentration through a semi-permeable membrane is called osmosis.
Q.9 Carry out the following osmosis experiment:
Take four peeled potato
halves and hollow each one out to make potato cups. One of these potato cups
should be made from boiled potato. Put each potato cup in through containing
water. Now
(a) keep cup A empty.
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in
cup C
(d) Put one teaspoon sugar
in boiled potato cup D.
Keep this set up for two hours. Then observe
the four potato cups and answer the following:
Explain why water gathers in
the hollowed portion of B and C.
Why is potato A necessary
for this experiment.
Explain why water does not
gather in the hollowed out portions A and D.
Ans.
(i) Water
gathers in the hollowed portion B and C because living plasma membrane of
potato cup acts as semi-permeable membrane. There is higher concentration of
water in through than the sugar solution of B and salt solution of C potato cup
respectively. So, by process of osmosis water moves into potato cups B and C.
(ii)
Potato A functions as control experiment which indicates that the cavity
does not induce movement of water.
(iii) Water does not gather in the potato cup A
because it does not possess higher osmotic concentration than the cell of
potato.
Potato cup D is boiled cup. It does not
have living cell and the membrane of the potato cells have lost their
permeability. As a result, when teaspoon of sugar is added into hollowed
portion of boiled potato cup D, water does not come out from within the potato
cells into the hollowed protein.
Q10. Which
type of cell division for growth ands repair of body and which type is involved
in formation of gametes?
Ans.
For growth and repair of body- Mitosis
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