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Biology Paper 2

SECTION A (40 Marks)

Answer ALL questions in this section n in the spaces provided

a) What is meant by the term sex linkage? GENETICS (1mk)

b) Name 2 sex linked genes in humans.

c) In Drosophila melanogaster, the inheritance of eye colour is sex linked. The gene for red eye Colour is dominant. A cross between a homozygous red eye female and a white eyed male. Work out the phenotype ratio of F1 generation (Use R to represent the gene for red eyes)

8 marks


Kosgei and Onyancha collided during a football match, and each got a bruise. Kosgei’s bruise stopped bleeding after 10 minutes while Onyancha’s bruise continued bleeding and he had to be taken to hospital for treatment. TRANSPORT IN PLANTS AND ANIMALS

a) Explain the process which brought about stoppage of Kosgei’s bleeding. (5mks)

b) Distinguish between blood clotting and haemogluttination. (2mks)

c) Name the disease that Onyancha could be suffering from. (1mk)

8 marks


The diagrams below represent the structure of a Nephrone. Study it and answer the questions that follow. EXCRETION AND HOMEOSTASIS

a) i) State the physiological process by which solutes are selectively re-absorbed back in blood at the part labeled B. (1mk)

ii) How is the part labeled B adapted to carry out the physiological process named in 3 (a) (i) above. (1mk)

b) In which part of the kidney is the part labeled A abundantly found. (1mk)

c) On the diagram above, indicate the direction of flow of blood using arrows at the part labeled

d) State the functions carried out by the following hormones in the functioning of the Nephron

i) Aldosterone (2mks)

ii) Anti-duretic hormone (2mks)

8 marks


The diagram below shows an organelle found in most cells. Study it and answer the question that follows. RESPIRATION

a) Give the name of the organelle. (1mk)

b) What is the full name of the major chemical compound that is formed in the organelle. (1mk

c) Name the gas required by the organelle in order to form the compound in (a) above. (1mk)

d) Give the name and function of the in folding labeled H

Name (1mk)


e) A student observed a row of 16 epidermal cells in a microscopic field that was 8mm in diameter.

Calculate the average length of each cell in micrometer. (3mks)

8 marks


In attempt to estimate the number of weaver birds in a small woodland, 435 weaver birds were captured marked and releases. Three days later 620 were captured, 75 of which were marked.

a) Calculate the approximate size of weaver birds population in the woodland. (2mks)

b) What are the disadvantages of this method? (2mks)

c) What assumptions must be made during this investigation? (2mks)

d) List down 2 other methods that can be used to estimate the number of organisms in a given habitat. ECOLOGY (2mks)

8 marks

SECTION B (40 Marks)

Answer question 6 compulsory and either question 7 or 8

Form three students at Mua secondary school studied the population growth of two species of beetles T. Confusum and T. Casteneum. The beetles were grown in a box with limited supply of flour. The box was kept in a warm place for 200 days. The beetles were counted at certain intervals and the

20 marks


results tabulated as shown below. ECOLOGY

a) Using the same axis draw the graphs of the number of beetles in the box against time(8mks)

b) How many beetles were present in the 70th day

T. Confusum (2mks)

T. Castenum (2mks)

c) Account for the shape of T. confusum curve between day

i) 0 – 10 (2mks)

ii) 60 -80 (2mks)

iii) 120-140 (2mks)

d) i) Suggest what happened to T. Casteanum between day 80 and 160 (2mks)

ii) What biological phenomena is represented by observation made in d (i) above. (1mk)

e) State one factor that may determine the distribution of animals in a given area. (1mk)

20 marks


Discuss the various evidences which show evolution has taken place. EVOLUTION (

20 marks


Discuss how the leaves are adapted to the process of photosynthesis. NUTRITION IN PLANTS AND ANIMALS

20 marks

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