MARANDA HIGH SCHOOL
Kenya Certificate of Secondary Education
PRE-MOCK EXAMINATIONS 2024
231/2 BIOLOGY
Paper 2
March 2024 – TIME: 2 Hours
Name: …………………………………………………... Adm No: ……….
……
Class: ……………Candidate’s Signature: …….……….. Date:
……/03/2024.
INSTRUCTIONS TO CANDIDATES
o Answer all the questions.
o Answers must be written in the spaces provided in the question paper.
o Additional pages must not be inserted.
o Candidates may be penalized for recording irrelevant information and for incorrect spellings.
FOR EXAMINER’S USE ONLY
Section Question Maximum Candidate’s
Score Score
1 8
A 2 8
3 8
4 8
5 8
6 20
1
B 7 20
8 20
1. Bile and pancreatic juice are important secretions in animal nutrition.
a) In which part of the digestive system do the above juices exert their influence?
(1 mark)
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i).Which of the two secretions should be mixed with chyme first for efficient
digestion? (2 marks)
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ii). Explain your answer above. (2 marks)
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b) Explain why:
i) It is not necessary to eat too much protein in the diet. (2 marks)
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ii). Liver is recommended in the diet of anaemic persons. (2
marks)
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2. Below is a representation of an independent unit of the biosphere. Use it to
answer the questions that follow.
a) Identify the unit represented above. (1 mark)
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b) i) Compare the primary productivity of the plants R and Q. (1 mark)
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ii) Account for your answer above. (2 marks)
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c) Give two differences between the chloroplasts of plants Q and R. (2 marks)
Chloroplast of Q Chloroplast of R
d) Name:
i) The instrument that you can use to measure light penetration in the unit
above. (1 mark)
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ii) The class to which the animal in the illustration belongs. (1 mark)
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3. (a) The diagram below represents a longitudinal section through the human eye.
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(i) Name the parts labeled A and B. (2 marks)
A ______________________________________________________________
B_______________________________________________________________
(ii) Explain the changes that would occur on the structure labelled A when a person
in a dark room switches on lights. (2 marks)
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(iii) Explain how part labelled D is adapted to its functions. (2
mark)
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(b) Give functions of the following parts of human brain.
(i) Optic lobe. (1 mark)
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(ii) Cerebellum. (1 mark)
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4. (a) Distinguish between a sex linked trait and a sex linked gene. (2 marks)
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(b) Sexual reproduction is great source of variation. Explain. (2 marks)
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(c) The beak length in a given bird species in Gwassi Hills Forest is linked to the
X chromosome. The beaks can be long or short. A recessive allele t is
responsible for short beaks. Use a genetic cross to show the genotypes of a cross
between a short beaked male bird and a long beaked female bird. (4 marks)
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5. The photographs below illustrates different biological phenomena.
a) N a m e the biological phenomena represented by photograph M. (1 mark)
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b) Give the significance of phenomenon represented by photograph P. (1 mark)
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c) Explain how the change in photograph Q occurs. (2 marks)
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d) Identify which of the two animals X and Y will have the least biomass. Give a
reason for your answer. (2 marks)
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e) Photograph N shows the behavior of an animal during hot weather. Explain the
significance of the phenomenon. (2 marks)
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6. An athlete undertook a race that lasted ten minutes. The concentration of lactic
acid in his blood from the beginning of the race to 45 minutes after the race
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determined at five minutes interval. The results were as shown in the table
below.
Time in
minutes 0 5 10 15 20 25 30 35 40 45 50 55
Lactic acid
concentration 20 24 74 98 88 78 70 66 62 58 54 50
mg/ml
a) On the graph provided, draw a graph of lactic acid concentration against
time. (6 marks)
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b) (i) By how much did the lactic acid increase at the end 13th minute? (1 mark)
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(ii) What is the concentration of lactic at 48th minute? (1 mark)
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c) Account for the high rate of lactic acid production up to 20th minute.
(2 marks)
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d) Account for the decline in lactic acid concentration after the excersise.
(2marks)
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e) (i) In man, glucose molecule is broken down aerobically to yield 2880KJ of
energy while anaerobic breakdown of the glucose molecule yield 150KJ of
energy. Give explanation for the difference. (2 marks)
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ii) Write down a balanced equation to show fermentation in plants. (1 mark)
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f) (i) Other than carbohydrate, name two other respiratory substrates. (2 marks)
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(ii) Under what condition does each of the substrate named in f (i) above
respired? (2 marks)
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h) What do you understand by the term obligate anaerobes? (1 marks)
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7. Describe various evidences that supports the theory of organic evolution.
(20 marks)
8. Describe how water moves from the soil to the leaves in a tree. (20 marks)
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