POST MOCK 2024
BIOLOGY
231/3 (PRACTICAL)
PAPER 3
TIME: 1¾ HOURS
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NAME……………………………………………… SIGN………………………..
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INDEX NO……………………………………… ADM NO……………………
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Kenya Certificate of Secondary Education.
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CONFIDENTIAL INSTRUCTIONS TO SCHOOLS
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REQUIREMENTS
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Each candidate will require;
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(a) Specimen R- a piece of ripe pineapple fruit
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(b) 2mls Benedict’s solution placed in a test tube with a dropper
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(c) 2mls of 10% Sodium hydroxide solution placed in a test tube with a dropper
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(d) 2mls of 1% Copper sulphate solution placed in a test tube with a dropper
(e) Source of heat
(f) 4 test tubes in a rack
(g) 2 Droppers
(h) Scalpel/Razor blade
(i) Pestle and mortar
(j) Filter paper
(k) 4mls DCPIP solution placed in a small beaker with a dropper
(l) 4mls of 0.1% solution of Ascorbic acid supplied in a test tube
(m) White tile
POST MOCK 2024
BIOLOGY
231/3 (PRACTICAL)
PAPER 3
NAME……………………………………………… SIGN………………………..
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INDEX NO……………………………………… ADM NO……………………
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Kenya Certificate of Secondary Education.
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INSTRUCTIONS TO CANDIDATES
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(a) Write your name, Admission number and your other details in the spaces provided above.
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(b) Spend the first 15 minutes of the time allocated to read through the question paper before
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commencing your work
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(c) Answer all the questions in the spaces provided.
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(d) Additional pages must not be inserted
For Examiner's Use Only
QUESTION MAXIMUM SCORE CANDIDATE’S SCORE
1 14
2 14
3 12
Total Score 40
Answer all the questions in the spaces provided.
1. You are provided with the following reagents and materials.
Specimen R
Benedict’s solution
Sodium hydroxide solution
Copper sulphate solution
Source of heat
3 test tubes in a rack
Droppers
Scalpel/Razor blade
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Pestle and mortar
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Filter paper
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Study the specimen R provided.
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(a) Identify the type of fruit.
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(b) With reasons, identify the method of dispersal for the specimen.
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Method of dispersal (1 mark)
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Reasons (2 marks)
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(c) By use of the scalpel provided, peel off the outer cover of the specimen R to reveal the inner
juicy part. Extract a small portion of the juicy part, place in a mortar and mash it using a pestle.
Use the filter paper provided to filter the extract from the specimen R.
Divide the extract from specimen R into two portions each 2cm3 and use them as follows;
Portion one
Use the reagents provided to test for the food substances present in portion 1. Use the table below
as a guide. (6 marks)
FOOD PROCEDURE OBSERVATION CONCLUSION
SUBSTANCE
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PORTION TWO
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(d) (i) To 1cm3 of DCPIP in a test tube, add 0.1% solution of Ascorbic acid drop by drop until
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the colour of DCPIP disappears. Shake the test tube after addition of each drop. Record the
number of droplets used. (1 mark)
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ii) To another 1cm3 of DCPIP in a test tube add the portion two drop by drop, shaking the test
tube after addition of each drop until the colour of DCPIP disappears. Record the number of
drops used …………………………………………………………………………………
(1 mark)
iii) From the results obtained in (d) (i) and (ii) above, calculate the percentage of Ascorbic acid in
the juice obtained from specimen R. Show your working (2 marks)
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2. Study the photographs below and answer the questions that follow.
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(a) (i) By use of a flow chart, show the possible energy flow in the ecosystem above.(1 mark)
(ii) State two ways in which energy is lost from one trophic level to the next one. (2 marks)
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(b) With observable reasons, identify the classes of specimen X and Z
Specimen X
Class ………………………………………………………………………………… (1 mark)
Reasons (2 marks)
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Specimen Z
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Class (1 mark)
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Reason
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(c) Describe two adaptations of organism labeled Y to its habitat. (2 marks)
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(d) Study the photograph below and answer the questions that follow.
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(i) Which part of the plant is represented by the cross-section shown above (1 mark)
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(ii) Give two observable reasons for your answer in (d)(i) above. (2 marks)
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(iii) Give one adaptation of the part labeled T to its function. (1 mark)
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3. Study the photographs below and answer the questions that follow.
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(a) Identify the following parts as (2 marks)
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F ...…………………………………………………………………………………………
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G ………………………………………………………………………………………….
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(b) (i) Identify the secretions stored in part labeled G (1 mark)
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(ii) Give two functions of the secretions you have identified in (b)(i) above . (2 marks)
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(c) (i) Give two major roles of the part labeled J . (2 marks)
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(d) (ii) State the hormone secreted by the part labeled H . (1 mark)
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(e) Study the photograph below and answer the questions that follow.
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(f) (i) Identify the following parts. (2 marks)
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K ...…………………………………………………………………………………………
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L …………………………………………………………………………………………..
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(ii) Give two adaptations of the part labeled M (2 marks)
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