cameroon gce A/L june 2003 Biology Paper 2

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June 2003

1. (a) How is the morphology and anatomy of a leaf adapted to photosynthesis?
(b) Outline the mechanism of carbon dioxide fixation (Dark reaction) in C4 plants.
(c) Why is it more advantageous to grow C4 plants than C3 plants?

2.(a) Discuss four mechanisms by which roots take up water and mineral salts from the soil.
(b) How are these substances distributed to all parts of the plant?
(c) How do xerophytes limit the loss of water from their aerial parts? (8, 8, 4 mks)

3. (a) Distinguish excretion and osmoregulation.
(b) Make a large labelled diagram of the mammalian nephron. .
(c) On the basis of structure in relation to function, discuss the following processes:
(i) Ultrafiltration (ii) Selective reabsorption. (2,5, 13 mks)

4. (a) What do you understand by Genetic Engineering?
(b) Briefly outline the stages of genetic engineering of bacteria.
(c) In man, the gene for haemophilia (h) is sex-linked and recessive to the gene for normal blood dotting
(H) Using appropriate notations make crosses with the following phenotypic pairs, indicating the
V expected phenotypic and genotypic ratios resulting from tire crosses:
(i) Haemophiliac woman with normal man
(ii) Normal woman (Heterozygous) with a haemophiliac man.
(iii) Normal woman (Homozygous) with a haemophiliac man (5, 6, 9 mks)

5. (a) Briefly examine the following ecological concepts:
(i) Water cycle
(ii) Trophic level
(iii) Land pollution
(b) How can bur laird be conserved to ensure greater survival of species?

6. (a) Explain the role of the following in digestion in a mammal
(i) Salivary glands
(ii) Oxyntic or parietal cells
(b) Describe the mechanism for the uptake of glucose and amino adds in the ileum of mammals.

7. (a) What do you understand by isometric and allometric growth?
(b) Explain the following terms as used in growth:
(i) Growth curve
(ii) Growth rate
(iii) Relative growth rate.
(c) What problems are encountered when measuring growth in multicellular organisms?
(2,12,6 mks)

8. Write short notes on the following :
(i) Counter current multiplier principle
(ii) Oxygen debt
(iii) All-or-nothing law
(iv) Synaptic transmission A