FORM FOUR EVALUATION
Kenya Certificate of Secondary Education 2009
MARKING SCHEME
BIOLOGY PI
1. Height; weight; skin colour; size of the ears/ eyes Rej. Length
Any three collect; for every discontinuous example mentioned, it cancels the correct answer.
(3mks)
2. Elector pilli muscles contract; Hair stands erect (to trap air); Sweat glands produce less sweat;
blood vessels contract/ vasoconstriction.
Any three correct. Rej. Sweat glands stop producing sweat.
(3mks)
3.
(i) Glucose; Rej starch/carbohydrate: penalize if light stage products are mentioned
(ii) Chlorophyll traps light; use for photolysis/ break water to H+ions
(3mks)
4.
(i) Coarse adjustment knob.
- raises or lowers the body tube / rough focusing of the specimen;
(ii) Diaphragm
- regulate/ controls the amount of light into the condenser;
(2mks)
5. (a) Fertilization – fusion of male and female nuclei gametes ; to form a zygote; Rej fusion of
gametes
(b) One male nuclei fuses with egg to form a (diploid) zygote; while the other male nuclei fuses
with (two) polar cells to form (triploid) endosperm nucleus;
(4mks)
6.
(a) A bone of the vertebral column;
(b) (i)Thoracic vertebra; rej thoracic bone/ thoracic alone
(ii) Presence of long neural spine; short transverse process; have facets (for rib articulation)
capitular demi tubular facets)
(4mks)
7. Arteries have narrower lumen / thicker muscular walls that maintain pressure;
(The left ventricle of) the heart pumps blood under high pressure to arteries;
(2mks)
8. (a) (i) Food web;
(ii) Three;
(b) Sun;
(3mks)
9. (i) Mouth / buccal cavity; duodenum;
(ii) it requires alkaline medium;
(3mks)
10. (i) Streamlined body; Rej streamlined shape
(ii) Sausage / inner membrane folded;
(iii) Funnel shape;
(3mks)
11. Promote cell division/ cell elongation; initiates fruit formation without fertilization/
parthenocarpy; formation of side branches of stem; inhibits growth of adventitious roots; promotes
dormancy in buds; Activates enzymes during germination;
(4mks)
12. (a) As the temperature increases the rate of enzyme reaction increases up to a maximum B; on
further increase in temperature the enzyme action decreases (BC);
(2mks)
(b) At low temperatures the enzymes are inactive; while at high temperatures the enzymes are
denatured;
(2mks)
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13. (a) Pyramid of number is a (diagramatic) representation of numbers of organisms at each trophic
level in a food chain; while biomass is a (diagrammatic) representation of dry weight / dry mass of
organisms at each trophic level in a food chain;
(b) Biomass is relatively constant ; Owotte (3mks)
14. (a) Sertoli cells – nourishment of spermatids/ immature sperms/ sperm cell / spermatozoa;
(b) Epidydimis – site for temporary storage of sperm cells / contracts to allow ejaculation of
sperms;
(c) Seminiferous tubule – site for spermatogenesis/ sperm synthesis/ sperm formation; (3mks)
15. (a) Transpiration ; Acc rate of transpiration
(b) Prevents evaporation of water from the surface;
(c) Turns blue, Acc. Change from pink to blue.
(3mks)
16. – less sweat produced ;
- High metabolic rate leading to production of more urine;
(2mks
17. (i) Insects – Exoskeleton;
(ii) Earthworm – Hydrostatic skeleton;
(iii) Man – Endoskeleton
18. (i) fats / lipids;Acc. Oils
(ii) Release large amount of energy per molecule on complete oxidation;
Produces a lot of water on oxidation ;(use for other metabolic activities)
(3mks)
19. (a) Mutation I – Deletion;
Mutation II – Inversion;
(b) Gene mutation – changes in the sequence of nucleotide in a DNA sequence;
Chromosomal mutation – changes in chromosome structure or number;
(4mks)
20. (a) – (Weak) carbonic acid ; acc bicarbonate ions/hydrogen carbonates
- carbamino haemoglobin;
(b) Carbonic anhydrase;
(3mks)
21. Swallow plenty of sea water to increase amount of water in the body;
- have chloride secretory cells in their gills to remove excess salts;
- Eliminates nitrogenous waste in form of trimethylamine oxide which requires little water for
elimination;
- Few / small glomeruli thus slow filtration rate in the Kidneys;
(3mks)
22. – Sensory; motor ;Relay ; intermediate;
(3mks)
23. (a) Arachnida; Rej; wrong spelling
(b) Mites; spider,
(3mks)
24. – Thin walls for faster diffusion of gases;
- Moist surface for dissolving gases;
- Large surface area for maximum diffusion /gaseous exchange;
- (Highly) vascularised to enhance /maintain / facilitate diffusion; Rej. Thin/ moist alone.
(any 3 (3mks)
25. (a) Lysosomes;
(b) Mitochondria;
(2mks)
26. (i) Hypertonic solution; Acc highly concentrated solution
(ii) Hypotonic solution; Acc more dilute solution
27. (a) Seedling A – epigeal germination;
Seedling B – hypogeal germination;
(b) Required for respiration/ oxidation to release energy;
(2mks)
(3mks)
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