Name the phenomenon which helps fresh water unicellular organisms (e.g. Amoeba) continuously gain water in their bodies. Also, name the mechanisms by which these organisms throw out excess of water from their bodies.

(b) Give at least two examples in plants where similar phenomenon in used to gain water.

1. Osmosis helps fresh water unicellular organisms (Amoeba) to gain water in their bodies. 2. Contractile vacuole helps in osmoregulation. It throws out excess of water from their bodies.

(b) (i) Absorption of water by the plant root hairs occurs due to osmosis.

(ii) In plants, cells, tissues and soft organs such as leaves, buds, young shoots, flowers, fruits maintain turgidity due to osmotic absorption of water.