Science(Form 2) - Simple Note of Topic Two

3512 Words Feb 18th, 2011 15 Pages
SCIENCE - FORM 2
Nutrition

CLASSES OF FOOD

1. Food is a basic necessity for all living things.

2. Food is important in order to : (a) Provide energy to carry out physical activities. (b) Provide energy for the physiological activities in life such as reproduction, digestion and excretion. (c) Build new cells and ti repair tissues in the body. (d) Protect the body from deseases. (e) Maintain the body temperature. (f) Promote growth. 3. Food can be divided into seven classes which are : (a) Carbohydrates (b) Protein (c) Fats (d)
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2. Fat is a food class that provides energy to the body. Fats supply twice as much energy as carbohydrates. 1 g of fats produce 38 kJ of energy.

3. Other functions of fats include : (a) As a heat insulator under the skin to reduce heat loss from the body. (b) To protect organs such as the heart and the kidneys from the injury. (c) To dissolve vitamins A, D, E and K in the body. (d) To prevent the loss of water from the surface of the skin by the secretion of oil.

4. Fat that exists in the form of liquid is called oil.

5. Fats are divided into : (a) Plant fats - palm oil, margarine, groundnut oil and coconut oil. (b) Animal fats - butter, milk, egg yolk and cheese.

6. Animal fats have a higher cholesterol level compared to plant fats.

7. Fat molecules are formed from glycerol and fatty acids.

8. Extra fat is kept by the body under the skin.

9. The presence of fat in food can be tested by rubbing a food sample on a filter paper. A translucent spot on the filter paper shows that the food has fat.

10. Fats can also be tested by the alcohol-emulsion test : (a) A few drops of enthanol are mixed with a fat simple. Then, shake the mixture vigorously. (b) Then, cold water is added. (c) The mixture turns into a cloudy white emulsion if fat is present.

(D) Vitamins

1. Vitamins
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