MASENO SCHOOL
2025 MOCK EXAMINATION
Kenya Certificate of Secondary Education
231 / 3 - BIOLOGY (PRACTICAL)
Monday 28th July, 2025 Unique Identifier No...........................
8.00 a.m. - 9.45.a.m. Signature..............................................
Instructions to candidates
For examiner’s use only
INSTRUCTIONS TO CANDIDATES
a) Write your Unique Identifier number the sign in the spaces provided at the top of this page.
b) Answer all questions.
c) You are required to spend the first 15 minutes of the1 ¾ hours allowed for this paper reading
the whole paper carefully before commencing your work.
d) Answers must be written in the spaces provided in the question paper. Additional pages must
not be inserted.
e) The paper consists of 8 printed pages.
f) Candidates should check to ascertain that all the pages are printed as indicated and that no
questions are missing.
g) Candidates MUST answer the questions in English
h) Candidate may be penalized for recording irrelevant information and for incorrect spelling
especially of technical terms
For Examiners Use Only
Question Maximum Score Candidate’s Score
1 12
2 15
3 13
Total score 40
THE MASENO SCHOOL MOCK COMMITTEE – 2025
2
1. You are provided with the following:
Liquid K
Filter paper
Substance B
Test-tubes
Two 10 ml measuring cylinders
Two labels
(a) Test for the food substance present in liquid K (4 marks)
Food substance Procedure Observation Conclusion
(b) Label two test-tubes A1 and A2. Put 2 ml of liquid K in each test-tube followed by 2 ml of
water. Shake test-tube A1 well and leave to settle. Add 2 ml of substance B in test-tube A2,
shake properly and leave to settle. Write your observations in the table below (2 marks)
Test-tube Observation
A1
A2
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
3
(c) Identify the process that took place in test-tube A2 (1 mark)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
(d) Explain the significance of the process identified in (c) above in human beings (2 marks)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
(e) Name the part of alimentary canal where the above process occurs (1 mark)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
(f) Name two chemical substances in human body that play a similar role as substance B (2 marks)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
…………………………………………………………………………………………………….
(g) Name another way of achieving mechanical digestion along the alimentary canal rather than the
one investigated above (1 mark)
……………………………………………………………………………………………………
…………………………………………………………………………………………………….
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
4
2. You are provided with specimens E and F. Examine them.
(a) With a reason, identify the Kingdom to which the above specimens belong to
Kingdom (1 mark)
……………………………………………………………………………………………………..
Reason (1 mark)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
(b) State four morphological differences between members of classes of the specimens E and F
above (4 marks)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
(c) Which type of germination is exhibited by specimen F? Give a reason for your answer
(2 marks)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………..
(d) Name one environmental factor that was necessary for growth of the above specimens (1 mark)
……………………………………………………………………………………………………
……………………………………………………………………………………………………..
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
5
(e) Draw a well labeled diagram of specimen E (3 marks)
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
6
3. Specimen F and the following organisms exists in a certain ecosystem. Study them.
(a) Construct a simple food chain to show energy flow in the above ecosystem (3 marks)
………………………………………………………………………………………………...…
……………………………………………………………………………………………………
(b) The biomass of the above organisms is shown in the table below.
Organism Biomass (g/cm2)
F 200
H 50
G 100
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
7
(i) Construct a pyramid of biomass to illustrate transfer of energy among the above
organisms (5 marks)
(ii) Account for the shape of the pyramid of biomass drawn in b (i) above (4 marks)
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
(c) Apart from using food chain and food web, give another possible way of representing energy
flow (1 mark)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
8
(d) Identify two sampling methods that could be used to estimate the population of specimen F in
its natural habitat (2 marks)
……………………………………………………………………………………………………
……………………………………………………………………………………………………
……………………………………………………………………………………………………
…………………………………………………………………………………………………...
THIS IS THE LAST PRINTED PAGE
THE MASENO SCHOOL MOCK COMMITTEE - 2025
231/3 Biology Paper 3
