July 12, 2011 KCSE Exams
SECTION A (40 marks)
Answer ALL the questions in this section in the space provided.
1 the figure below shows changes that take place during
menstrual cycle in human.
(a) Name the hormones whose concentrations are
represented by curves F and G. (2 marks)
(b) State the effects of hormones named in (a)
above on the lining of the uterus. (2 marks)
(c) (i) name the hormones which is released
by the pituitary gland in high concentration
on the 14th day of the menstrual cycle.
(ii) State two functions of the hormone named in
(c )(i) above. (2 marks)
(d) State the fertile period during the menstrual cycle.
(2) A pea plant with round seeds was crossed
with a pea plant that had wrinkled seeds.
the gene for round seeds is dominant over
that for wrinkled seeds.
using letter R to represent the dominant
(a) The genotype of parents if plant with round seeds
was heterozygous; (2 marks)
(b) The gametes produced by the round and
wrinkled seed parents; (2 marks)
round seed parents ………………………………………….
wrinkled seed parents ………………………………………
(c) The genotype and phenotype of F1 generation.
show your working. (3 marks)
(d) What is a test-cross? (1 mark)
3 the equation below represents a process that
(a) Name the process. (1 mark)
(b) State two conditions necessary for the process
to take place. (2 marks)
(c) State what happens to the end-product of the
process. (5 marks)
4 (a) give three reasons in each case why
support necessary in :
(i) Plants; (3 marks)
(ii) Animals. (3 marks)
(b) Why is movement necessary in animals?
(5) a freshly obtained dandelion stem
measuring 5cm long was split length
wise to obtain two similar pieces.
the piece were placed in solutions of
different concentrations in Petri dishes
for 20 minutes.
the appearance after 20 minutes is as
(a) Account for the appearance of the
piece in solutions L1 and L2. (6 marks)
(b) State the significance of the biological
process involved in the experiment.
SECTION B (40 marks)
Answer question 6 (compulsory) and wither
question 7 or 8 in the space provided after
6 An experiment was carried out to investigate
transpiration and absorption of water in
sun flower plants in their natural environment
with adequate supply of water. The amount of
water was determine in two hour intervals.
the results are shown in the table below.
(a) Using the same axes, plat graph to
show transpiration and absorption
of water in grammes against time of
the day. (7 marks)
(b) At what time of the day was the amount
of water the same for transpiration and
and absorption ? (1 mark)
(c) Account for the shape of the graph of:
(i) Transpiration; (3 marks)
(ii) Absorption. (3 marks)
(d) What would happen to transpiration and
absorption of water if the experiment was
continued till 05 00 hours? (2 marks)
(e) Name two factors that may affect transpiration
and absorption at any given time. (2 marks)
(f) Explain how the factors you named in (e) above
affect transpiration. (2 marks)
7 describe the nitrogen cycle. (20 marks)
8 (a) state four characteristics of gaseous
exchange surfaces. (4 marks)
(b) Describe the mechanism of gaseous exchange
in a mammal. (16 marks)