(a) A balanced diet contains all the six classes of food which are carbohydrates, protein, fat, vitamins, water and mineral salts.
(I) Examples of the classes of food

vitamins	fruits, vegetables such as bitter leaf, egg, milk, liver, oil etc.
fat	Groundnut, melon, butter, margarine, palm oil, cod liver, soya bean oil.
water	water in plants, water in animal, water in drinks, beverages and food
mineral salt	vegetables, fruits such as mango, orange, apple, cashew etc. banana,bones,egg, table salt
Carbohydrates	Rice, bread, cassava, yam, cocoyam, potato etc

(c)(i) Functions of protein in human are:
(i) It is useful for growth and formation of new cell.
(ii) Protein is used for repair of worn out tissues.
(iii) It functions in the formation of Hormones.
(iv) It yields certain amount of energy.
(v) It is also useful for formation of enzymes.
(ii) A child with protein deficiency will have the. following features:
(i) The child will have retarded growth.
(ii) Loss of weight is also common to such child
(iii) He will develop swollen legs, oedema and swollen feet
(iv) He develops cracked and split skin
(v) The child will have distended and swollen stomach resulted to kwashiorkor.
(vi) He develops pale body.
(vii) There is also a change in the hair; the hair becomes reddish brown
(viii) The child also develops thin and tiny legs
(ix) The child will have distended and smoker stomach resulted to kwashiorkor.
(d)(i) One organelle in a living cell that produces enzymes is Ribosomes.
(ii) Enzymes that act on proteins are:
(i) Pepsin
(ii) Trypsin
(iii) Rennin.