Term 3 Form 3 Biology Exam Paper 2

 

231/2

TIME: 2HRS

SECTION A  (40 MKS)

ANSWER ALL THE QUESTIONS IN THIS SECTION.

1. The diagram below represents a transverse section of a young plant organ.

• Identify the class of plants from which it was obtained(1mk)

 

• With a reason, state the organ of the plant from which it was obtained. (2mks)

 

• Name the parts  labeled A and B                                                 (2mks)
  A

B

• State the functions of the parts labeled C and D. (2mks)

C

D­­­­­­­­­­­­­

1. e) Explain how a waxy cuticle reduces water loss in leaves. (1mk)

 

 

2. The diagram below represents a stage during

(a)  (i)Identify the stage of cell division               (1 mk)

 

(ii)Give three reasons for your answer in (a) (i) above         (3mks)

 

(b)  Name the structure labeled M                                     (1 mk)

 

1. c) List three differences between mitosis and meiosis (3mks)

Mitosis	Meiosis

3.The diagram below represents  a mammalian nephron

(a)        Name

(i)         The structure labeled P                                                               (1mk)

 

(ii)       The portion of the nephron between point X and Y                   (1mk)

 

(b) What is the process that takes place at point Q ?(1mk)

 

(c) Give one substance present at point R but absent at point S in a healthy mammal

(1mk)

 

(d) The appearance of the substance you have mentioned in (c) above is

a symptom of a certain disease caused by a hormone deficiency. Name the

(i) Disease(1mk)

(ii) Hormone1mk)

(e) State two structural modifications of nephrons found in the desert mammals                 (2mks)

 

 

4. The chart below shows a feeding relationship in a certain ecosystem.

• Construct two food chains ending with a tertiary consumer in each case          (2 mks)

 

• Which organism has the largest variety of predators in the food web?(1 mk)

 

• Name two secondary consumers in food web                             (2 mks)

 

• Suggest three ways in which the ecosystem would be affected if there

was a prolonged drought. (3mks)

 

5. A student placed a drop of pond water on a glass slide and observed it under the light microscope. The student observed many fast moving organisms, one of which is represented in the diagram below.

(a)(i) Name the Kingdom to which the organism belongs     (1mk)

(ii) Give three reasons for your answer in (a) (i) above    (3mks)

 

1. b) Name the structures labelled N,P and Q. (3mks)

N

P

Q

1. c) State one feature that enables the organism to move fast.(1mk)

 

SECTION B ( 40 MKS)

QUESTION 6 IS COMPULSORY. ANSWER EITHER QUESTIONS 7 OR 8

6. A scientist carried out an investigation to find out the population growth of mice under laboratory conditions. Twenty young mice were placed in a cage and the results obtained from the investigation were as shown in the table below.

 

Time in months	Number if mice
0	20
2	20
4	65
6	115
8	310
10	455
12	450
14	310
16	145
18	160

 

 

1. a) On the grid provided, draw a graph of the number of mice against time. (6mks)
2. b) Account for the changes in mice population between
3. i) 0 to 2 months (2 mks)

 

1. ii) 2 to 6 months (2 mks)

 

iii) 6 to 10 months                                                                               (2 mks)

 

1. iv) 12 to 16 months (2 mks)

 

1. c) i) Between which two months was the population change greatest? (1 mk)
2. ii) Calculate the rate of population change over the period in (c) (i) above.         (2 mks)

 

 

1. d) What change in population would be expected if the investigation was

continued to the 19th month?                                                             (1 mk)

 

1. e) To obtain the observed results state two variables that were kept constant during the investigation.                                                                                     (2 mks)

 

7. Discuss the causes, effects and control of water pollution.(20mks)
8. a) State four characteristics of respiratory surfaces in animals. (4mks)
9. b) Describe the breathing mechanism in mammals.                    (16mks)