a) Name two reproductive hormones secreted by the pituitary gland in women. (2 marks)
b) Explain how a seed is formed after an ovule is fertilized. (4 marks)
c) State two ways by which acquired immuno deficiency syndrome (AIDS) virus is transmitted. (2 marks)

The diagram below represents a mammalian nephron.
a) Name the;
i) Structure labelled P.
ii) protion of nephron between x and y. (2 marks)
b) Name the process that tkaes place at point Q. (1 mark)
c) Name one substance present at point R but absent at point S in a healthy mammal. (1 mark)
d) The appearance of the substance you have mentioned in (c) above is a symptom of a certain disease caused by a hormone
deficiency. Name the (2 marks)
i) disease ................................................................................................................................................
ii) hormone................................................................................................................................................
e) State the structural modification of nephron in the desert mammals. (2 marks)

a)Mwalimu Andrew of Mwisho wa Lami High school quarrels with his wife Fiolina over the identify of their child. Andrew is heterozygous blood group A and Fiolina is homozygous blood group B. The child born is of blood group O. Andrew has sued Fiolina for divorce over infidelity. Does Andrew have a chance of winning the case? Show your working. (4 marks_)
b)A transmission of Rh+ve blood was given to a patient of Rh-ve blood. After one week a similar transfusion was given to the
same patient. What was likely to be the effect of the second transfusion? (2 marks)
c) State two consequences of gene mutations. (2 marks)

The diagram below represents a food web in a certain ecosystem.
a) Name the trophic level occupied by each of the following: (2 marks)
i) Caterpillar ............................................................................................................................................
ii) Small insects ........................................................................................................................................
b) From the food web, construct two food chains which end with lizards as tertiary consumer. (2 marks)

c) i) Which organisms have the least biomass in this ecosystem? (1 mark)
ii) Explain the answer in c(i) above. (3 marks)

a) A shoot of seedling exposed to light on one side bends towards the source of light as it grows.
i) Name the response exhibited by the shoot of the seedling. (1 mark)
ii) Explain how the bending towards the source of light occurs. (3 marks)
b) A person was able to read a book clearly at arm's length but not at normal readings distance;
i) State the defect the person suffered from ? (1 mark)
ii) What was he unable to read the book clearly at normal distances? (2 marks)
iii) How can the defect be corrected? (1 mark)

An experiment was carried out to investigate haemolysis of human red blood cells. The red blood cells were placed in different concentration of sodium chloride solution. The percentage of haemolysed cells was determined. The results were as shown in the table below.
Salt concentration (g/100cm³)(%) 0.33 0.36 0.38 0.39 0.42 0.44 0.48
Red blood cells (haemolysed)(%) 100 91 82 69 30 15 0
a) i) On the grid provided, plot a graph of haemolysed red blood cells against salt concentration. (6 marks)
ii)At what concentration of salt solution was the proportion of haemolysed cell equal to non-haemolysed cells? (1 mark)
iii) State the percentage of cells haemolysed at salt concentration of 0.45%. (1 mark)
b) Account for the results obtained at:
i) 0.33 percent salt concentration. (3 marks)
ii) 0.48 per cent salt concentration. (3 marks)
c) What would happen to the red blood cells if they were placed in 0.50 percent salt solution? (3 marks)
d) Explain what would happen to onion epidermal cells if they were placed in distilled water. (3 marks)

Describe the role of hormones in the growth and development of plants.

Discuss the various evidences which show that evolution has taken place.