4. (a) (i) Explain the condition sickle cell anaemia [3 marks]
(ii) Name three substances that are essential in blood clotting [3 marks]
(b) List four symptoms of vitamin C deficiency [4 marks]
(c) Explain the following terms

(i) Tidal air;
(ii) Complemental air;
(iii) Residual air. [6 marks]

(d) Mention four ways of preventing constipation [4 marks]

                                   
                     
                     

OBSERVATION

This question was attempted by few candidates and their performance was poor. In part (a)(i) candidates could not correctly explain the condition sickle cell anaemia, in (a)(ii) candidates could not correctly name ubstances that are essential in blood clotting. In part (b) candidates could not correctly list symptoms of vitamin C eficiency. In part (c) candidates could not correctly explain the following terms (i) tidal air (ii) complemental air (iii) residual air. In part (d) candidates could not correctly mention ways of preventing constipation.
However, the expected answers were ad follows:

4(a)(i) Explanation of sickle cell anaemia
It is an inheritable disease
Red blood cells becomes crescent/curved/sickle shaped
Sickle red blood cells break up easily when passing through capillaries
Causing anaemia
Oxygen carrying capacity is reduced
Tissue are cut off from oxygen supply/tissues die
Causing severe pains/crisis.

(ii) Substances essential in blood clotting
Protrombin/thrombin
Calcium
Fibrinogen
Thromboplastin/thrombokinase
Blood platelets
(b) Symptoms of Vitamin C deficiency
scurvy/bleeding gums
unhealthy skin/scaly skin/dry skin/bruising
reduced resistance to infection
teeth disorder
bleeding under the skin.

        (c)            Explanation of terms
(i) tidal air
volume of air that enters or leaves lungs
during normal breathing
      (ii)      complemental air
volume of air drawn into the lungs
during forced inspiration
(iii) residual air
volume of air left in the lungs
after a forced expiration

(d) Ways of preventing constipation
physical exercises
eating roughage/vegetables
drinking plenty of water
eating enough fruits
avoid eating between meals.