Page 15 - Biology Form Two

Biology for Secondary Schools

Vitamins are formed by the combination
of glucose and some mineral elements.
Most of the vitamins are synthesised
by autotrophs, particulary green plants.
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Mammals can synthesise vitamins A
and D using plant molecules obtained
in their food. Examples of foods
containing vitamins are fruits and Figure 1.6: Sources of vitamins

vegetables, as shown in Figure 1.6.

Functions of vitamins
Vitamins play an important role in the metabolic activities of both plants and

animals, such as promoting functions of immune enzymes and nervous systems.
They are also important in the formation of bone tissue and red blood cells.
Deficiency or excess intake of vitamins can cause health problems. Table 1.1
shows examples of vitamins, their sources, functions, and deficiency symptoms.

Table 1.1: Sources, functions, and deficiency symptoms of vitamins
Deficiency
Vitamin Sources Functions
symptoms
Vitamin A Liver, milk, eggs, Formation of (i) Night blindness
(Retinol) oranges, and yellow membranes of the eyes, (ii) Increased risk of
vegetables such as and the respiratory infections
carrots and pumpkins tract
Vitamin B Lean meat, liver, (i) Assists in Beriberi, a disease
1
(Thiamine) eggs, mushroom, carbohydrate characterised by a loss
brown rice, and metabolism of appetite, muscle
whole grain cereals (ii) Helps in muscle cramps, nerve disorder,
coordination and heart failure

Vitamin B Liver, meat, Metabolism of all (i) Cracks and sores
2
(Riboflavin) mushroom, and foods, and the release around the mouth
whole grain cereals of energy to cells and nose
(ii) Visual problems

Student’s Book - Form Two 9

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BIOLOGY FORM 2 NEW.indd 9 05/10/2024 15:36:18