- State four characteristics of fruits dispersed by animals. (4 marks)
- State two roles of each of the following hormones in menstruation:
- luteinising hormone; (2 marks)
- oestrogen. (2 marks)
- State four characteristics of fruits dispersed by animals. (4 marks)
- The diagram below illustrates the role played by red blood cells in transportation carbon (IV) oxide.
- Other than carbon (IV) oxide transportation in the red blood cells, name the other form of carbon (IV) oxide transportation in humans. (1 mark)
- Name substance F (1 mark)
- Name the enzyme marked G and state its role in the reaction. (2 marks)
Enzyme
Role
- Explain why transportation of carbon (IV) oxide in red blood cells is advantageous. (2 marks)
- Explain the role of calcium ions in blood clotting. (2 marks)
- Other than carbon (IV) oxide transportation in the red blood cells, name the other form of carbon (IV) oxide transportation in humans. (1 mark)
- Describe the mechanism of gaseous exchange in plants through the lenticels. (3 marks)
- Explain each of the following:
- the tracheoles lack spiral bands of chitin; (3 marks)
- the floor of the mouth is lowered during inhalation in a bony fish. (2 mark)
- Describe the mechanism of gaseous exchange in plants through the lenticels. (3 marks)
- How is sex determined in man? (4 marks)
- Differenciate between sickle cell anaemia and sickle cell trait. (2 marks)
- Explain why people with sickle cell trait have an adaptive survival advantage over normal individuals in malaria endemic regions, (2 marks)
- How is sex determined in man? (4 marks)
- The diagram below represents the transverse section of the spinal cord.
- Name the part labelled H. (1 mark)
- State two functions of the fluids found in the part labelled J. (2 marks)
- Give a reason for the colour of white matter. (1 mark)
- Name and give the function of the enzyme found at the part labelled K.
Name (1 mark)
Function (2 marks) - On the diagram, use an arrow to show the direction of the impulse transmission along the neurone labelled I. (1 mark)
SECTION B. (40 marks)
Answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8.
- Name the part labelled H. (1 mark)
- An experiment was done to determine the uptake of nitrogen from the soil by broad bean seedlings. The experiment was done with one set of seedlings M grown in the atmosphere enriched with carbon (IV) oxide and another set up of seedlings N grown in normal atmosphere.
The amount of nitrogen in each seedling was measured in milligrams at intervals of ten days. The table below shows the results obtained.- Using the same axis, draw line graphs of nitrogen uptake by the two (M and N) sets of broad bean seedlings against time. (8 marks)
- Determine the rate of uptake in Set M between 65 and 85 days. (2 marks)
- What is the relationship between carbon (IV) oxide concentration in the air and nitrogen uptake. (1 mark)
- Account for the relationship in (c) (i) above. (3marks)
- What is the relationship between carbon (IV) oxide concentration in the air and nitrogen uptake. (1 mark)
- What would happen to the concentration of nitrogen in the seedlings in set M, if after 75 days the seedlings are trasferred to normal atmosphere. (1 mark)
- Explain your answer in (d) (i) above. (2 marks)
- State three ways in which nitrogen fixation occurs. (3 marks)
- Using the same axis, draw line graphs of nitrogen uptake by the two (M and N) sets of broad bean seedlings against time. (8 marks)
- Explain how each of the following factors affect the rate of photosynthesis:
- temperature; (2 marks)
- chlorophyll concentration. (2 marks)
- Describe the process of cabohydrate digestion in human beings. (16 marks)
- Explain how each of the following factors affect the rate of photosynthesis:
- How does excretion take place in plants? (4 marks)
- Describe the role of human skin in homeostasis. (16 marks)
- How does excretion take place in plants? (4 marks)