Page 70 - Understanding NCERT Science 09

• Chromoplasts that contain chlorophyll are called chloroplasts
and they perform photosynthesis.
• The primary function of leucoplasts is storage.
• Most mature plant cells have a large central vacuole that
helps to maintain the turgidity of the cell and stores
important substances including wastes.
• Prokaryotic cells have no membrane-bound organelles, their
chromosomes are composed of only nucleic acid, and they
have only very small ribosomes as organelles.
• Cells in organisms divide for growth of body, for repalcing
dead cells, and for forming gametes for reproduction.

Exercises

1. Make a comparison and write down ways in which plant
cells are different from animal cells.
2. How is a prokaryotic cell different from a eukaryotic cell?
3. What would happen if the plasma membrane ruptures or
breaks down?
4. What would happen to the life of a cell if there was no Golgi
apparatus?
5. Which organelle is known as the powerhouse of the cell? Why?
6. Where do the lipids and proteins constituting the cell
membrane get synthesised?
7. How does an Amoeba obtain its food?
8. What is osmosis?
9. Carry out the following osmosis experiment:

• Take four peeled potato halves and scoos 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.
10. Which type of cell division is required for growth and repair
of body and which type is involved in formation of gametes?

THE FUNDAMENTAL UNIT OF LIFE 59

Rationalised 2023-24