July 12, 2011 Facebook Twitter LinkedIn Google+ 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.

(1 mark)

(ii)  State two functions of the hormone named in

(c )(i) above.                                          (2 marks)

(d)   State the fertile period during the menstrual cycle.

(1 mark)

(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

gene state:

(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

take place.

(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?

(2 marks)

(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.

(2 marks)


                 SECTION B (40 marks)

Answer question 6 (compulsory) and wither

question 7 or 8 in the space provided after

question 8.

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)



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