KCSE Mokasa Biology Paper 2 Joint Exams and Marking Schemes Free Access

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SIGN …………………………INDEX NO ………………… ………STREAM……………

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Biology Paper 2

(Theory)

Time: 2 Hours

MOKASA II JOINT EVALUATION EXAMINATION

Kenya Certificate of Secondary Education

Write your name, Index Number in the spaces provided above
Write the date of examination in the space provided above
Answer ALL the questions in section A in the spaces provided below each question in the question paper
In section B, answer question 6(Compulsory) and either question 7 or 8

FOR EXAMINER’S USE ONLY

Section	Question	Maximum Score	Candidate’s Score
A	1	08
	2	08
	3	08
	4	08
	5	08
B	6	20
B	7 or 8	20
	TOTAL	80

a) Disease X is caused by a recessive gene located only on Y sex chromosome. A man suffering from the disease X got married last year, 2022. Using a punnet square show the probability of their 3^rd born child suffering from the disease XUseletter N to represent the gene for disease X. (4 marks)

b) An individual has XXX sex chromosome is formed as a super female. Explain how this condition comes about. (2 mark)

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c) A mother at Kenyatta National Hospital gave birth to triplets and were separated at birth and brought up under different conditions. The table below gives information about them when they met after 20 years.

Features	Alice	Grace	Aby
Weight	70kgs	69kgs	64kgs
Height	1.82m	1.86m	1.7m
IQ	120	120	122
Blood group	B	O	B
Tongue rolling	Non roller	Non-roller	Non-roller

Which of the triplets are likely to have been identical (1 mark)

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Give a reason for your answer (1 mark)

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a) Describe the process of fertilization in humans (3 marks)

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b) What determines primary sexual characteristics and secondary sexual characteristics (2 marks)

Primary

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Secondary

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c) Urethra is an organ involved in two organ systems in the body. Name the organ systems (1 mark)

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d) Give the functions of the following cells in seminiferous tubules of male reproductive system (2 marks)

(i) Sertoli cells

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(ii) Interstitial cells

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The graph below depicts the concentration of two antibodies from a patients’ blood sample: one in response to injection with antiserum against snake bite and the other in response to injection with a toxoid vaccine.

a)Account for the shape of the curves of injection with toxoid vaccine(2marks).

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b)Name the type of immunity conferred to the patient when; (2 marks)

Given second injection of antiserum against snakebite

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ii) Given first injection with a toxoid vaccine

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c) A farmer was attacked by a swarm of bees and died. Explain how the bee sting caused death. (3 marks)

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d) State how monocytes destroy pathogens (1 mark)

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The figure below shows the iris and pupil subjected to different environmental conditions.

Identify the parts labeled A and B

A …………………………………………………………………… (1 mark)

B …………………………………………………………………… (1 mark)

Describe the event that leads to the appearance of B in diagram Z.

(2 marks)

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(i)What is the importance of the event occurring in (b) above (1 mark)

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Identify one cause of hypermetropia (1 mark)

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Distinguish between Rods and Cones (2 marks)

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The diagram below shows a section through the skin of a polar bear.

a)i) Name the part labeled D. (1 mark)

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ii) Explain the thermoregulatory function of D named in a (i) above. When the body temperature is below optimum (3 marks)

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b) What is the effect of bleaching creams to the part labeled C (1 mark)

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c) Name two homeostatic roles of the skin (2 marks)

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d) Describe how part labeled A adapts the organism to its habitat (1 mark)

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The table below shows the growth of two types of animals. Animal A and animal B from the time they were hatched for a period of 60 days. The growth was measured in millimeters after every week for a period of nine weeks. The two animals were provided with adequate space, food and optimum temperature

Time (weeks)		1	2	3	4	5	6	7	8	9
Body length	Animal A	3	3	10	11	23	23	32	33	42
(mm)	Animal B	2	3	4	20	35	70	92	95	102

Plot the growth curve of the body length against time of the two animals on the same axis. (7 marks)

Name the growth pattern represented by;

Graph of animal A (1 mark)

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Graph of animal B (1 mark)

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Account for the growth pattern of the animal A (3 marks)

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Account for the shape of the graph for animal B between;

Week 1 – week 3 (3 marks)

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Week 3 – week 7 (3 marks)

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Name two hormones responsible for the increase in length of the animal A.

(2 marks)

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a) Discuss various ways in which man has artificially used plant growth hormones in agriculture and horticulture (8 marks)

b) Describe how xerophytesare adapted to conserve water (12 marks)

a) Describe the process of digestion of skimmed milk along the alimentary canal (10 marks)

b) Discuss the practical applications of Anaerobic respiration (10 marks)

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KCSE Mokasa Biology Paper 2 Joint Exams and Marking Schemes Free Access

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