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 Biology Paper 2,May/June 2009.
 Questions: 1 2 3 4 5 6 7 8 Main
Strength
Weakness/Remedies

Question 1

(a) State one function of each of the following structures:
(i) Arteries;
(ii) Capillaries;
(iii) Veins;
(iv) Xylem;
(v) Phloem. [5 marks]

(b) Described the changes that take place in the composition of human
blood as it passes through the:
(i) Lungs;
(ii) Liver;
(iii) Kidney;
(iv) Small intestine. [12 marks]

(c) List the cellular components of blood. [3 marks]

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observation

This was a popular question in the section.

Most candidates attempted the question and could state the functions of the listed structures. In stating the functions of the arteries and veins the candidates merely stated carrying blood away from the heart and carrying blood towards the heart. They did not state the exceptions namely the pulmonary artery and veins which led to loss of marks.

Most candidates stated all the components of blood including plasma rather than just the cellular components and since there was no penalty they scored full marks.

Only an insignificant number of candidates could describe the changes in blood as it passed through the organs listed in 7(b). Expected answers include:

Changes in blood composition as it passes through the
Lungs
- Oxygen is added to the blood;
- Carbon dioxide is removed from the blood;
- Water is removed from the blood.

Liver
- Urea is added to the blood;
- Hormonal level is reduced;
- Glucose level is reduced;
- Worn out erythrocytes are removed from the blood.

Kidneys
- Water, urea, some glucose, dissolved salts, mineral salts are reduced in the blood.

Small Intestine –
- simple sugars/glucose, amino acids, water; salts and vitamins are added to the blood.