Answer. Proteins make up more than 50% of the dry weight of animals. Each protein and carries out a specific function. Sources and uses of protein are as follows
(i) Sources of animal's proteins are meat, mutton, chicken, fish, eggs. These are used as food by human beings as they are essential for the formation of protoplasm.
(ii) Enzymes are proteins that are produced by the living cells. They catalyze the chemical reactions taking place in the bodies. They are highly specific and have extraordinary efficiency. Many enzymes are used as drugs. They control the bleeding and are used for the treatment of blood cancer.
(iii) Hides are proteins. These are used to make leather by tanning. Leather is used to make shoes, jackets, sports items, etc.
(iv). Proteins are found in bones. When bones are heated they give gelatin. Gelatin is used to make bakery items.
(v) Plants also synthesize proteins such as pulses, beans, etc. These are used as food.