( (a)         (i)      What are enzymes?                                                                            [2 marks]
             (ii)       State five characteristics of enzymes.                                                [5 marks]
            (iii)       Name two enzymes involved in carbohydrate digestion in the body.
                                                                                                                                   [2 marks]

(b)    Name the end product of digestion of the following classes of food:

(i)  carbohydrates;

(ii)    proteins;
 (iii)    fats.                                              [3 marks]

(c)    State two uses each of the following classes of food in the human body;
(i)    proteins;
(ii)    vitamins.                                                                                               [4 marks]

(d)  State two benefits each of including the following food substances in the diet of
humans:

(i)  roughage;

(ii)   water.                                                                                                      [4 marks]

This question was attempted by few candidates but their performance was good.

 In part (d)(i) however, candidates misinterpreted benefits of including roughage to mean use of vitamins. 

The expected answers were as follows:
 
Vitamins:

1. prevent deficiency diseases/named diseases e.g. night blindness; ricket; scurvy; beriberi, etc.;
2. important in the formation of bones
3. required in the absorption of calcium and phosphorus.

Roughage:

• aids digestion and makes food bulky;
• it helps the food to pass through the digestive system easily/aids easy movement peristalsis of food through the bowels/prevents constipation;
• reduces the risk of bowel cancer/keeps colon healthy.