NAME…………………………………………… CLASS……………. ADM NO…………….

DATE……………………………… SIGN……………… INDEX NO………………………..

231/1
BIOLOGY PAPER 1
THEORY
JUNE 2025
TIME: 2 HOURS

KASSU-MEC
BIOLOGY MOCK EXAMINATIONS
Kenya Certificate of Secondary Education (K.C.S.E)

INSTRUCTIN TO CANDIDATES
- Write your name and index number in the spaces provided above.
- Sign and write the date of examination in the spaces provided above.
- This paper consists of 0NE sections A.
- Answer all the questions in Section A in the spaces provided.
- The paper contains 11 printed pages.

For examiner’s use only

Question Maximum Score Candidates Score

1 – 25 80

1|Page
1. (a) Name the cell organelles which are abundant in: (2marks)
(i) Muscle cells
………………………………………………………………………………….
(ii) Pancreas
………………………………………………………………………………….
(b) The cell membrane is made up of two constitutes molecules. List them. (2marks)
………………………………………………………………………………………………
………………………………………………………………………………………………

2. Some students set up the experiment as shown below to demonstrate a certain physiological
process.

a. What is the aim for the set up shown above? (1mk)

…………………………………………………………………………………………………….
b. Explain the observations made at the end of the experiment represented by B. (2mks)
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
…………………………………………………………………………………..…………………

2|Page
3. Identify two external features in animals that are used to classify organisms. (2mks)
…………………………………………………………………………………………………
…………………………………………………………………………………………………
………………………………………………………………………………………………….

4. How does nutrition differ in plants and animals? (1mk)

…………………………………………………………………………………………………
…………………………………………………………………………………………………
5. List two use of the energy obtained from the process of respiration. (2 marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………

5. (a) Explain why the fine adjustment knob is used only when using the high power objective

(1mark)

………………………………………………………………………………………………………
……………………………………………………………………………………………………...

(b) A student estimated the diameter of the field of vies to be 2.8mm.The diameter was
occupied by four onion epidermal cells. Estimate in the diameter of each cell. (2marks)
…………………………………………………………………………………………………
…………………………………………………………………………………………………
………………………………………………………………………………………………….
(a) Differentiate between saprophytism and parasitism. (2marks)
…………………………………………………………………………………………………
…………………………………………………………………………………………………
………………………………………………………………………………………………….

(b) State the role played by light energy during photolysis. (1mark)
………………………………………………………………………………………………………
………………………………………………………………………………………………………

3|Page
6. (a) Name the forms in which carbohydrates are stored in (2marks)

(i) plant cells

……………………………………………………………………………………

(ii) animal cells

………………………………………………………………………………………

(b) Explain the importance of cleaning your teeth after the last meal at night rather than the first
meal in the morning (1mark)
………………………………………………………………………………………………………
………………………………………………………………………………………………………

7. a) Explain why there no an individual male survivor with Turners syndrome and all females
with above condition are infertile [2marks]
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
b) State any two components of a DNA nucleotide [2marks]
………………………………………………………………………………………………
………………………………………………………………………………………………

8. The photograph below shows a potted plant after two weeks when placed at a horizontal
position in a dark room.

(a) Name the type of response shown. (1mark)

…………………………………………………………………………………….………

4|Page
 (b) State the biological significance of the response above to the plant. (1 mark)
…………………………………………………………………………………………..

………………………………………………………………………………………….

(c) Explain how the response in (a) above occurred (3 marks)

…………………………………………………………………………………………………
…………………………………………………………………………………………………
………………………………………………………………………………………………….
9. A person fell from the third floor of a storey building and had part of his brain damaged
indicate the part of the brain damaged if the person suffers from the following. (2 marks)

I. Loss of memory and speech …………………………………………… …………

II. Inability to maintain proper body balance and posture ………………………………..

10. The diagram below shows the position of an image in a defective eye.

(a) Name the defect (1mark)

………………………………………………………………………………………………….

(b) Explain how the defect in (a) above can be corrected. (1mark)

………………………………………………………………………………………………………

(c) How are nocturnal animals adapted to seeing? (1mk)

………………………………………………………………………………………………………

5|Page
 (d) State one advantage of an animal having binocular vision (1mark)

………………………………………………………………………………………………………

11. Name the support tissues in plants. (2 marks)

……………………………………………………………………………………………..
………………………………………………………………………………………………
12. Locomotion in a bony fish in water is controlled by various fins. Name the fins responsible
of the following movements. (2 marks)
(a) Pitching…………………………………………………………………………………….
(b) Yawing …………………………………………………………………………………….
13. The figure below represents the female part of a flower. Use it to answer the questions that
follow.

a) Name parts labelled A and B

(2marks)

A……………………………………………………………………………………………………

B……………………………………………………………………………………………………

b) State the significance of part D.

(1mark)

……………………………………………………………………………………………………

14. a) What is alternation of generations as used in classification? (1mark)

……………………………………………………………………………………………………

6|Page
b) Name the spore producing structure of a moss plant.
(1mark)

………………………………………………………………………………………………………

c) State two characteristics shared by a cockroach and a crab.

(2marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………

15. The figure below shows the pattern of growth in an insect measured by increase in fresh
weight.

a) What is the name given to this kind of growth curve?

(1mark)

………………………………………………………………………………………………………

b) Explain the changes that occur in the insect from point A to B on the graph with emphasis on
what happens at X
(2marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………

7|Page
c) State 2 importance of metamorphosis in insects. (2marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………

16. The chart below illustrates a natural matter decay. Study it and then answer the questions that
follow.

a) State the biological process A and B. (2marks)

A……………………………………………………………………………………………………
B……………………………………………………………………………………………………

b) Name the organism that is involved in process D.

(1mark)

………………………………………………………………………………………………………

c) Name the intermediate compound between ammonia and nitrates in the cycle. (1mark)

………………………………………………………………………………………………………

17. State 2 adaptations of the stomata in xerophytes to their habitats.

(2marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………

8|Page
18. What is the significance of the testes of a mammal hanging outside the body in males?
(1mark)

………………………………………………………………………………………………………

(a) Name the function of the Cowper’s gland in males. (1mark)

……………………………………………………………………………………………………

a) How is the fallopian tube adapted to its function?

(1mark)
……………………………………………………………………………………………....
19. The table below represents the biomass of organisms at various trophic levels.

Organism Biomass per species in

Kilograms
Grasshopper 9000
s
Mice 3000
Snakes 900
Grass 14000
a) Draw a pyramid of biomass to represent the above information. (2marks)

b) Suggest a reason why the biomass reduces from the producers towards the tertiary
consumers. (1mark)
………..…………………………………………………………………………………………

9|Page
20. The figure below shows two cells obtained from two different organisms while the cells were
undergoing a certain stage of cell division. Study them and answer the questions that follow

a) What stage of cell division were the cells undergoing? (1mark)

………………………………………………………………………………………………………

b) Identify with a reason the type of cell division from which the organism in diagram 2 was
obtained
(2marks)

………………………………………………………………………………………………………
……………………………………………………………………………………………………

21. The diagram below represents a fruit from a dicotyledonous plant.

(a) To what group of fruits does the specimen belong? .........................................................

(1mark)

22. The pancreas and the liver work together in the regulation of blood sugar in the human blood.
state the role of each of these organs when the concentration of glucose is below the norm.
(2marks)
Liver
…………………………………………………………………………………………………
…………………………………………………………………………………………………

10 | P a g e
 Pancreas
…………………………………………………………………………………………………

(b) State one effect of removing the pancreas from the body. (1 marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………

23. Define the term immunity. (1mark)

……………………………………………………………………………………………………
……………………………………………………………………………………………………....
b) Distinguish between natural immunity and acquired immunity. (1mark)
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………….

c) Identify one immunizable disease in Kenya. (1mark)

………………………………………………………………………………………………………

24. (a) State two adaptations of the alveolus to its functions. (2marks)
………………………………………………………………………………………………………
………………………………………………………………………………………………………
(b) Suggest a reason for asthmatic patient producing a wheezing sound during breathing? (1mk)

............................................................................................................................................................
............................................................................................................................................................
(c) Name the causative agents of the following diseases. (2 mark)
Pneumonia
…………………………………………………………………………………………………..
Tuberculosis
…………………………………………………………………………………………………..
25. The diagram below represents a unit of gaseous exchange in man.study it carefully and
answer the questions that follows.

11 | P a g e
(a) Name the gases labelled G and H. (2 marks)

G:……………………………………………………………………………………………………

H: ………………………………………………………………………………………...…………

(b) State difference of appearance of blood in terms of colour of blood at A and at B. (1 marks)

………………………………………………………………………………………………………
………………………………………………………………………………………………………

12 | P a g e