Name: ……………………………………………………………………..…… Adm No.............
Class: …………. Candidate’s sign ……………………....
Date: …………………………
231/3
BIOLOGY
PAPER 3
PRACTICAL
JULY 2025
TIME: 1 ¾ HOURS
CATHOLIC DIOCESE OF ELDORET
PRE-KCSE MOCK EXAMINATIONS 2025
Kenya Certificate of Secondary Education
INSTRUCTIONS TO CANDIDATES:
Write your name, class and admission number in the spaces provided.
Sign and write date of examination in the spaces provided above
Answer all the questions.
You are required to spend the first 15 minutes of the 1 ¾ hours allowed for this paper reading the
whole paper carefully.
For Examiner’s Use Only:
QUESTIONS MAXIMUM SCORE CANDIDATE’S SCORE
1 14
2 12
3 14
TOTAL 40
This paper consists of 6 printed pages. Candidates should check to ascertain that all papers are
printed as indicated and that no questions are missing
1. You are provided with a visking tubing, a solution labeled E, Iodine solution labeled solution
F, Benedict’s solution labeled solution L and a piece of thread.
Tie one end of the visking tubing tightly using the thread provided. With the help of a dropper,
put 10 ml of the solution labeled E into the visking tubing. Tie the other end of the visking
tubing tightly.
Ensure that there is no leakage at both ends of the visking tubing.
Wash the outside of the visking tubing with water. Place the visking tubing in a 100 ml beaker.
Add distilled water into the beaker to reach the level of the liquid in the visking tubing. Allow
the set up to stand for 30 minutes or more.
a) Using 2 ml in a test-tube in each case, test for the food substance in the liquid outside the
visking tubing using; [6marks]
TEST Procedure Observation Conclusion
Iodine solution
(Solution F)
Benedict’s
Solution
(Solution L)
b) Using 2 ml in a test-tube in each case, test for the food substance in the contents of the
visking tubing using; [2marks]
TEST Procedure Observation Conclusion
Iodine solution
(Solution F)
Benedict’s Solution
(Solution L)
c) Account for your results in (a) and (b) above. (4marks)
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d) Highlight two roles of the physiological process demonstrated here. (2marks)
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2. The diagram below illustrates a gaseous exchange structure in human beings.
Y X
II
Z To blood
vessel P
a) Identify the structure. [1 mark]
b) Name;
i) Parts labelled X and Y. [2 marks]
ii) Blood vessel P. [1 mark]
c) Which gas is represented by;
I. ……………………………………………………………………………………………………… [1 mark]
II. ……………………………………………………………………………………………………… [1 mark]
d) How does the gas labelled II reach the inside of structure Y? [3 marks]
e) i. Name cell Z [1 mark]
ii. What is the significance of the shape of the cell named in e (i) above? [2 marks]
3. All members of plant division Spermatophyta exhibit alternation of generation. The
photographs below show stages in the growth and development of a spermatophyte.
a. Name;
i. Processes I and III. [2 marks]
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ii. Structures K, P, R and W. [4 marks]
K ………………………………………………………………………………
P…………………………………………………………………………..…
R ……………………………………………………………………………
W……………………………………………………………………………..
iii. The cell division process that occurs in structures J. [1 mark]
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iv. The products of the process named in a (iii) above. [1 mark]
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II
I
R Process III
b. Explain the role of the following in promoting process II in the flowering plants.
Petals. [2 marks]
Filaments. [2 marks]
c. The photographs above represent one of the phases in alternation of generations in a
spermatophyte. Name the phase. [1 mark]
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