BIOLOGY [2 Mark Question Answer]

Dough prepared for making idli rises when kept overnight due to the action of yeast. It becomes light, fluffy and sour. Yeast multiplies and produces carbondioxide which raises the dough.

Vegetables are dried to prevent the growth of microorganisms as they require moisture for their growth. They are stored in air tight containers so that microorganisms may not enter from the air.

Separation of fibres from the long lasting line stem of fibre plants, such as flax and jute is called retting of fibres. This is brought about by the action of bacteria on plant parts submerged in water.

Bacteria and fungi are called nature’s scavengers because they help in cleaning the earth. They decompose excretory products and dead remains of plants and animals into simple substances. Thus, they clear the earth of all the wastes.