BIOLOGY FORM THREE
1. Define the following terms as used in ecology: (3mks)
(a) Ecosystem
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(b) Biomass
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(c) Carrying capacity
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2. (a) what is respiratory quotient? (1mk)
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(b) The tristearin has the molecular formula C₅₇H₁₁₀O₆. Calculate the RQ for the
complete oxidation of tristearin acid. (3mks)
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3. Define the term alternation of generation. (2mks)
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4. A student caught an animal which had the following characteristics:
Body divided into two parts
Simple eyes
Eight legs
The animal belongs to which class? (1mk)
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5. Identify the phylum whose members possess a notochord. (1mk)
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6. A student collected the following different types of leaves from the school compound.
(a) Construct a dichotomous key to identify the leaves shown above. (3mks)
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7. A form one student trying to estimate the size of onion cells observes the following on the
microscope’s field of view. He counts 20 cells across the field of view which is 3mm.
Calculate the size of one cell in micrometres. (3mks)
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8. The diagram below represents a simplified trend of Nitrogen circulation in an ecosystem.
(a) What is the descriptive term applied to each of the organism A and D. (2mks)
A–
D–
(b) Name the chemicals C, F and E. (3mks)
C–
F–
E–
9. Name the products of anaerobic respiration in;
(i) Plants
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(ii) Animals
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10. Define the following terms: (2mks)
(a) Plasmolysis
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(b) Crenation
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11. The figure below represents a plant.
(a) State the division it belongs. (1mk)
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(b) Name the parts labelled A and B. (2mks)
A–
B–
12. Besides abdomen, name the other body parts of members of Arachnida. (1mk)
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13. Students of Chewoyet High School wanted to establish the population of ants in an ant
hill in the school compound. They caught 280 ants that they counted, marked and released
back to the habitat. After two days, they went back and collected 260 ants out of which
120 had the marks.
(a) What population estimation method did they apply? (1mk)
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(b) What is the total number of ants in that anthill? (3mks)
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14. (a) What is the significance of classification in Biology? (3mks)
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( b) The scientific name of rice is Oryza Sativa and that of bhang is Cannabis Sativa. Explain
why these two organisms cannot interbreed to produce a viable offspring. (2mks)
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15. (a) Define Homeostasis. (1mk)
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( b) Explain the role of the following in homeostasis: (3mks)
(i) Skin
(ii) Liver
(iii) Hypothalamus
16. State any roles of active transport in animals. (4mks)
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17. Give two ways in which some fungi are beneficial to humans. (2mks)
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18. How would you make a plasmolysed cell turgid? (1mk)
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19. State any two roles of active transport in animals. (2mks)
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20. Give two classes of sub-division Angio Spermatophyta. (2mks)
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21. Name the cell organelle that performs each of the following functions: (2mks)
(a) Destroy worn out organelles;
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(b) Tissue respiration;
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22. How does light as an abiotic factor influence the distribution of plants in ecosystem?
(3mks)
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23. A man was found to have blood group A+.
(a) What antigens does this blood group have? (2 marks)
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(b) Which blood groups can he receive from? (1 mark)
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24. The diagram below represents the external structure of a certain mammalian organ.
(a) Name the parts labelled X and Y . (2 marks)
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(b) State the function of the part labelled X . (1 mark)
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(c) Name the disease caused by accumulation of cholesterol on the walls of the part labelled
X (1mark)
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25. State the function of the following in mammalian trachea. (3 marks)
(a) Rings of cartilage
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(b) Mucus
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(c) Cilia
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26. Explain the significance of respiratory surfaces being; (2mks)
i) moist……………………………………………………………………………….
ii) highly vascularized………………………………………………………………………….
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27. In an experiment to investigate an aspect of digestion, two test tubes P and Q were
set up as show in the diagram below.
The test tubes were left in the bath for 30 minutes. The content of each test tube was
then tested for starch using iodine solution.
(a) What was the aim of experiment? (lmk)
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(b) What results were expected in test tube P and Q (2mks)
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(c) Account for the results you have given in b above in test tube P and Q (2mks)
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(d) Why was the set up left at 37°C (1 mk)
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(e) Name the carbohydrate stored in (2mks)
i. Mammalian liver
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ii. Potato tuber
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