Download 5. The Fundamental Unit of Life.

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1. Make a comparison and write down ways in which plant cells are different from
animal cells.
Solution:
Plant cell
Animal cell
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The outermost covering is the plasma
membrane.
Plastids are present.
Plastids are absent.
Vacuoles are large in size & lesser in number.
Vacuoles are smaller in size & more in
number.
Centrioles are absent but polar caps are
present.
Centrioles are present within centrosome.
Golgi apparatus is in the form of sub-units,
called dictyosomes.
Prominent and highly complex golgi apparatus
is present near nucleus.
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The outermost covering of the plant cell is the
cell wall which is formed of cellulose.
2. How is a prokaryotic cell different from a Eukaryotic cell?
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Solution:
Eukaryotic cell
Cell size is generally small (1-10 m m).
Cell is generally large (5-100m m).
Nuclear region called nucleoid and not
surrounded by a nuclear membrane.
Nuclear material is surrounded by a nuclear
membrane.
Only a single chromosome is present.
More than one chromosome is present.
Nucleolus is absent.
Nucleolus is present.
Membrane bound cell organelles are absent.
Cell organelles bound by membrane is
present.
Cell division by fission or budding.
Cell division mitotic or meiotic.
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Prokaryotic cell
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3. What would happen if the plasma membrane ruptures or breaks down?
Solution:
The plasma membrane or cell membrane separates the cell contents from the external
environment. Moreover, cell membrane is a selectively permeable membrane. So, it allows
the entry of substances which are required into the cell, and also the exit of the substances
which are not required by cell or are in excess.
The cell membrane also prevents movement of some materials through it. Thus, the danger
of losing essential compounds out of cell is avoided. Similarly, the substances, which are not
required by the cell, are prevented from entering into it.
The cell membrane is also semi permeable membrane. So, by osmosis it regulates the water
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CONTACT FOR MATHEMATICS GROUP/HOME COACHING FOR CLASS 11TH 12TH BBA,BCA,
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content of the cell.
From the above information, it is concluded that a cell cannot live without cell membrane.
4. What would happen to the life of a cell if there were no Golgi apparatus?
Solution:
Golgi apparatus pack and detach enzymes, hormones and other essential proteins and lipids
secreted by endoplasmic reticulum to target inside and outside the cell. Moreover, the
digestive enzymes, which remain concealed in lysosome, will remain free in the cytoplasm
killing the other cell content. Over all, in absence of golgi apparatus the cell will die.
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5. Which organelle is known as the powerhouse of the cell? Why?
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Solution:
Mitochondria are known as the ‘Power House’ of the cell. They are called so because the
energy required for various life activities is released by mitochondria in the form of ATP
molecules. The body uses energy stored in ATP for synthesis of new compounds and for
mechanical work. As ATP instantly provides energy, they are called energy currencies of the
cell.
6. Where do the lipids and proteins constituting the cell membrane get
synthesized?
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Solution:
Rough endoplasmic reticulum (RER) – Synthesizes proteins constituting cell membrane.
Smooth endoplasmic reticulum (SER) – Secretes lipids constituting cell membrane.
7. How does an Amoeba obtain its food?
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8. What is osmosis?
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Solution:
Amoeba has flexible cell membrane. It enables amoeba to engulf in food by the process
called endocytosis.
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Solution:
The passage of water from a region of its high concentration through a semi permeable
membrane to a region of low water concentration is known as osmosis.
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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 one should be made from a boiled potato. Put each potato cup in a
trough 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 the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the
following:
(i) Explain why water gathers in the hollowed portion of B and C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
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CONTACT FOR MATHEMATICS GROUP/HOME COACHING FOR CLASS 11TH 12TH BBA,BCA,
DIPLOMA CPT CAT SSC AND OTHER EXAMS Also home tutors for other subjects in DELHI AND OTHER MAJOR CITIES
EMAIL:2 [email protected] web site www.badhaneducation.in
BADHANEDUCATION D96 MUNIRKA VILLAGE NEW DELHI 110067 & VIKAS PURI NEW DELHI
CONTACT FOR COACHING MATHEMATICS FOR 11TH 12TH NDA DIPLOMA SSC CAT SAT CPT
CONTACT FOR ADMISSION GUIDANCE B.TECH BBA BCA, MCA MBA DIPLOMA AND OTHER COURSES 09810144315
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Solution:
(a) Water gathers in the hollowed portion of potato B and C because:
(i) Living plasma membrane of potato cup act as semipermeable membrane.
(ii) There is higher concentration of water in trough than the sugar solution of B and salt
solution of C potato cup respectively.
(iii) So, by process of osmosis water moves into potato cups B and C.
(b) Potato cup A is kept empty to act as control. This shows that osmosis occurs only when a
solution with low concentration of water is separated by semipermeable cell membrane from
the region of higher concentration of water.
(c) (i) In the potato cup A, there is no solution to cause osmosis to occur.
(ii) In the potato cup D, the potato cell membrane has lost the quality of semipermeability
due to boiling. So, no water movement occurs from the trough water into the potato cup D.
10. Can you name the two organelles that you have studied about, which contain
their own genetic material?
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Solution:
(i) Mitochondria and (ii) Plastid (chloroplast)
11. If the organization of a cell is destroyed due to some physical or chemical
influence, what will happen?
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Solution:
Each cell has got certain specific cell organelles. Each cell organelle performs a special
function, e.g., making of new material, removal of waste from the cell, release of energy etc.
If the organization of a cell is destroyed, the function of the cell organelle will be disturbed,
control of the nucleus will be lost. Ultimately the cell die.
12. Why are lysosomes known as suicide bags?
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13. Where do the ribosomes get synthesized?
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Solution:
Ribosomes get synthesized in nucleolus.
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Solution:
A lysosome is a membrane bound bag like structure which contains powerful enzymes. If
lysosome bursts, its enzymes eat up other organelles of its own cell. Therefore, they are
known as ‘suicide bags’.
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