(a) Name the phenomenon which helps fresh water unicellular organisms (e.g., Amoeba) continuosuly gain water in their bodies. Also name the mechanisms by which these organisma throw out exces of water from their bodies.
(b) Give at least two examples in plants where similar phenomenon in used to gain water.

Explanation

(a) Fresh water unicellular organisms (e.g., Amoeba) continuously gain water in their bodies due to osmosis. These organisms have contractile vacuoles to throw out excess of water from their bodies.
(b) (i) Absorption of water by the plant roots from the soil through root hairs occurs due to osmosis.
(ii) In plants, cells, tissues and soft organs (leaves, young shoots, flowers) maintain turgidity due to osmotic absorption of water.