Chapter 5 The Fundamental Unit of Life
Question
1. Make a comparison and write down ways in which plant cells are also
different from animal cells.
Answer:
Question
2. How is prokaryotic cell different from a eukaryotic cell?
Answer: Prokaryotic cell is generally smaller in size
(1-10 pm), nuclear region is poorly defined, the cell organelles are not
membrane-bound and has a single chromosome.
Eukaryotic cell is generally larger in size (5-100 pm), nuclear region is well
defined with nuclear membrane. Membrane-bound cell organelles are present and
has more than one chromosome.
Question
3. What would happen if the plasma membrane ruptures or breaks down?
Answer: If plasma membrane ruptures or breaks down then
molecules of some substances will freely move in and out.
Question
4. What would happen to the life of a cell if there was no Golgi apparatus?
Answer: Golgi apparatus has the function of storage,
modification and packaging of the products in vesicles. If there were no Golgi
bodies, packaging and dispatching of materials synthesised by the cell will be
stocked.
Question
5. Which organelle is known as the powerhouse of the cell? Why?
Answer: Mitochondria is known as powerhouse of the cell
because it releases the energy required for different activities of life.
Question
6. Where do the lipids and proteins constituting the cell membrane get
synthesised?
Answer: Lipids and proteins are synthesised in ER
[Endoplasmic Reticulum].
Question
7. How does Amoeba obtain it’s food?
Answer: Amoeba take it’s food by the cell membrane which
forms the food vacuole.
Question
8. What is osmosis?
Answer: Osmosis is the process of movement of water
molecule from a region of higher water concentration through a semi-permeable
membrane to a region of lower water concentration.
Question
9. Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato
cups, one of these potato cups 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.
Answer:
(i) Water gathers in B and C because in both the situations there is difference
in the concentration of water in the trough and water in the cup of Potato.
Hence, osmosis takes place as the potato cells act as a semi-permeable
membrane.
(ii) Potato A is necessary for this experiment for comparison, it acts as a
control.
(iii) Water does not gather in the hollowed out portions of A and D. As cup of
A does not have change in the concentration for water to flow. For osmosis to
occur one of the concentration should be higher than the other.
In cup D, the cells are dead and hence the semi-permeable membrane does not
exists for the flow of water and no osmosis takes place.
