1) Make a comparison and write down ways in which plant cells are different from animal cells.
They do not have a cell wall.
They have a cell wall made up of cellulose
They do not have chloroplast
they contain chloroplast
They have centrosome
they have centrosome
2) How is a prokaryotic cell different from a eukaryotic cell?
Size of the cell is generally small
Size of the cell is large
The nucleolus is absent.
Nucleolus present
3) What would happen if the plasma membrane ruptures or breaks down?
ANSWER:-If the plasma membrane ruptures or breakdown then the cell will not be able to exchange material from its surrounding by diffusion or osmosis.
4) What would happen to the life of a cell if there was no Golgi apparatus?
ANSWER: – If there is no Golgi apparatus then the packaging and transporting of materials synthesized by cell will not happen.
5) Which organelle is known as the powerhouse of the cell? Why?
ANSWER:-Mitochondria are known as the powerhouse of cells because the energy required for various chemical activities needed for life is released by mitochondria in the form of ATP.
6) Where do the lipids and proteins constituting the cell membrane get synthesized?
ANSWER:-Lipids are synthesized in the smooth endoplasmic reticulum (SER) and the proteins are synthesized in the rough endoplasmic reticulum
7) How does an Amoeba obtain its food?
ANSWER:-Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food-vacuole as shown in figure. Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out.
8) What is osmosis?
ANSWER:-Osmosis is the process in which water molecules moves from the region of high concentration to a region of low concentration through a semi-permeable membrane.
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 boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup an 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.
(i) Water gathers in the hollowed portions of set-up B and C because water enters the potato as a result of osmosis. Since the medium surrounding the cell has a higher water concentration than the cell, the water moves inside by osmosis. Hence, water gathers in the hollowed portions of the potato cup.
(ii) Potato A in the experiment acts as a control set-up. No water gathers in the hollowed portions of potato A.
(iii) Water does not gather in the hollowed portions of potato A because potato cup A is empty. It is a control set-up in the experiment. Water is not able to enter potato D because the potato used here is boiled. Boiling denatures the proteins present in the cell membrane and thus, disrupts the cell membrane. For osmosis, a semi-permeable membrane is required, which is disrupted in this case. Therefore, osmosis will not occur.