Question

Write short answers (2 or 4 lines) of the following questions :

1) why plant cell does not burst even if placed constantly in hypotonic solution?

2) why hydrophytes do not have cuticle on stem or leaves?

3) Marine protozoa do not have contractile vacuole, why?

4)Define Various aspects of homeostasis.

5) Define positive and negative feed back system with examples

6) Enlist osmoregulatory adaptations in terrestrial animals.

7) Enlist homeostatic functions of liver

8) Draw the chart of ornithine cycle.

9) State the names and effects of hormones on kidney.

10) Define renal failure and kidney stones.

11) Define feed back . Differentiate b/w negative and positive feed back.

12) why excreation does not pose problem in plants?

Answer 1

When the plant cell is placedin a hypotonic solution , it takes up water by osmosis and starts to swell, but thecell wall prevents it frombursting. The plant cell issaid to have become "turgid" i.e. swollen and hard. The pressure inside the cell rises until this internal pressure isequal to the pressure outside.

The plants (such as water lily), which are found in freshwater habitat either partly or completely submerged are termed ashydrophytes. They do not have any difficulty in obtaining water. The stemsand leaves of hydrophytesgenerally lack cuticle. Their stomata are large and present on the upper surfaces of leaves.

Marine protozoa do not have contractile vacuole unlike fresh water protozoabecause of the reason thatcontractile vacuole is used to store and remove excess water (due to endosmosis) which if comes in rapidly can cause the cell to burst