(a) What is a balanced diet? (b) (i) Name four classes of food other than proteins (ii) Give one example of food substance for each class named (c)(i) State...

Answer Details

(a) A balanced diet is a diet that contains all the classes of food (carbohydrates, proteins, fats and oils, vitamins, mineral salts, water and roughage) in the correct proportions needed by the body for proper growth, energy and health.

(b)(i) Four classes of food other than proteins, with (ii) one example each

(c)(i) Three functions of proteins in humans

• For growth and building of new cells and tissues.
• For repair of worn-out or damaged tissues.
• For the formation of enzymes, hormones and antibodies (and can be oxidised to give energy).

(ii) Appearance of a child with protein deficiency (kwashiorkor)

• Swollen belly and puffy (oedematous) face, hands and feet due to fluid retention.
• Thin, wasted limbs with poor muscle development and stunted growth.
• Reddish-brown, sparse hair; pale, scaly skin; and general weakness with a miserable, irritable look.

(d)(i) Organelle that produces enzymes: the ribosome (site of protein/enzyme synthesis).

(ii) Two enzymes that act on proteins: pepsin and trypsin (erepsin/peptidase also acceptable).