(a) What is a balanced diet? (b) Name the classes of food stating the importance...
BIOLOGY
WAEC 2007
(a) What is a balanced diet?
(b) Name the classes of food stating the importance of any two to the human diet.
(c) In a tabular form, state the source, substrate and end products of the following enzymes: (i) ptyalin: (ii) pepsin; (iii) lipase.
Explanation
(a) Balanced Diet;is a diet containing all the six food classes/types of food in the right proportion to meet the body's requirement for growth, repair and maintenance.
(b) Classes of food:
-Protein
-Carbohydrate
-Vitamins
-Water
-Mineral salts/nutrients
-Fats and Oils/Lipids.
Importance of food classes
| Food substances | Importance |
| Carbohydrate | Energy giving |
| protein | Growth/replacement/repair of worn out cells/repair of tissues |
| Fats and oil | Energy source/formation of adipose tissue for insulation |
| Vitamins | for proper functioning/maintenance of the body |
| Mineral salts/nutrients | play specific roles in metabolic processes/maintenance of the body |
| water | Medium for various metabolic processes/named processes |
(c) The source, substrate and end products of ptyalin, pepsin and lipase are tabulated below:
| Enzyme | Source | Substrate | End product |
| Pytalin | Salivary gland | cooked starch | maltose |
| pepsin | Gastric gland | protein | peptones/polypeptides/peptides |
| Lipase | pancrease | fat/oils/lipids | fatty acids and glycerol |
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