In genetics blood groups are determined by three genes represented by letter A, B and O.

A couple with blood group A female and blood group B male had a child with blood group O.

a) i) State the genotypes of the parents. (2 marks)

ii) State the gametes of the male parent. (1 mark)

b) Work out the probability of the above couple having blood group AB child. (5 marks)

c) Define the term co-dominance (1 mark)

An experiment was set up as shown below.

Contents of the beaker were tested for the presence of reducing sugars at start of experiment and after 30 minutes using Benedict’s solution. The results were recorded as shown overleaf.

a) Complete the table above. (2 marks)
b) i) Name the biological process that was being investigated. (1 mark)
ii) Account for the observations made. (3 marks)

c) Distinguish between cell physiology and cell specialization. (2 marks)

The diagram below represents a simplified nitrogen cycle.

a) Name the group of bacteria represented by: (2 marks)

A_____________

B_____________

b) i) Name the group of organisms represented by C. (1 mark)

ii) Give the reasons for your answer in b (i) above. (2 marks)

c) i) Define the term nitrification. (1 mark)

ii) Explain how excessive use of pesticides will affect nitrification. (2 marks)

a) i) What are vestigial structures? (1 mark)

ii) Give two examples of vestigial structures in man. (2 marks)

b) i) Explain the occurrence of plasmodium resistant to chloroquin treatment. (4 marks)

ii) Name the disease caused by plasmodium in human beings. (1 mark)

The diagram below represents a section through the mammalian ear.

a) Name the structures labelled H and J. (2 marks)
H _______________________________
J _______________________________

b) Explain how the structures labelled M and N are adapted to their functions.

M___________________________________(2 marks)

N___________________________________(2 marks)

c) State one function of the ear. (1 mark)

A 50 grams sample of finger millets was germinated on moist cotton wool. Half of the sample was grown in normal daylight and the other half in permanent darkness. Samples from each group were weighed every 48 hours. Their fresh mass was determined in each case and the following results were obtained.

a) On the same axes, plot graphs of the fresh mass against time. (7 marks)

b) Account for the difference between the two graphs. (4 marks)

c) What was the mass of the seedling in light and in the dark on the 17th day? (2 marks)

i) In dark

ii) In light

d) State two characteristics of the seedling grown in dark. (2 marks)

e) Explain two roles of each of the following in germination.

i) Water (2 marks)

ii) Oxygen (2 marks)

f) Name one hormone that plays a role in germination. (1 mark)

Describe how the mammalian skin is adapted to its functions

a) State one difference between a seed and a fruit. (1 mark)
b) Explain how fruits and seeds are adapted to their various methods of dispersal. (19 marks)