KCSE Past Papers 2011 Biology Paper 1 (231/1)


Biology Paper 1 (231/1)

1 (i) Nephritis;

(ii) kidney stones; (2 marks)

2 (a) equatioon

(b)Dental carries;

Periodontal/gingivitis/pyorhoea; (2 marks)

3(i) Identify similarities and differences between organisms;

(ii) Organize scientific knowledge in an orderly system;

(iii) Monitor emergence, presence and disappearance of organisms in and from the earth;

(iv) Grouping organisms for easy study;(3 marks)

4 (a) Sucking small insects/animals; (1 mark)

(b) A trap into which small animals fall and get trapped; (1 mark)

5 (a)

(b) (i) Chicken;

(ii) Grass; (2 marks)

6 (a)This is the study of the inter-relationship between organisms and their environment; (1 mark)

(b) The maximum population of a species than a particular habitat can support; Without depletion of resources.(1 Mark)

7 Water was hypotonic to cell sap of adjacent cells;

and these cells absorbed water through osmosis;

and their cell sap became less concentrated than those of the next cells;

The process was repeated until water reached the sugar solution; (4 marks)

8 Fused head and thorax/cephalothorax often protected by a carapace;

Gaseous exchange through gills;

Two pairs of antennae;

Five to twenty pairs of limbs;

A pair of compound eyes;

Three pairs of mouth parts (consisting of mandibles, maxillary, palp and labium) a pair of mandibles and 2 pairs of maxillae.(3 marks)

9 (a) Dicotyledonae; (1 mark)

(b) Monocotyledonae; (1 mark)

10 (i) Lactic acid in animals while in plants it is ethanol/alcohol;

(ii) No carbon IV oxide produced in anaerobic respiration in animals while anaerobic respiration in plants produces carbon IV oxide; (2 marks)

11. Moves the body tube through smaller distances to bring the image/specimen/object into sharper focus;Platform where specimen (on slide) is placed;(2 marks)

12. Chordata; ‘ Aves;(2 marks)

13. Source of energy; Storage materials;(2 marks)

14. (a) Dry/Arid/Semi-arid/Desert;

(b) Succulent/fleshy stem; reduced leaves/

leaves reduced into thoms/leaves modified into spines/spikes;(1 mark)

15. (a) To reduce layers of cells to allow light to pass through;

(b) To make the cells turgid/prevent drying up;

(c) To protect the lens on the objective;

16. (a) Weakened/defective valves in veins; causing blood/body fluid to accumulate; leading to swelling. (2 marks)

(b) When exposed to air they disintegrate/rupture/burst; releasing thromboplastin; thrombokinase (2 marks)

17.(a) L – Duodenum;

M – Pancreas; (2 marks)

(b) i) Bile;

(ii) Emulsification/emulsifies fats;

(iii) Provides alkalinic medium for enzyme action.

(iv) Neutralizes acidic chyme. (2 marks)

18. (a) Sublingual gland; submaxillary gland; parotid gland; submandibular First one (1 mark)

(b) Lubricating food; digestion of starch; moisten food; provide alkaline medium; First two (2 marks)

19. (a) (i) Skin;

(ii) buccal cavity/mouth cavity (2 marks)


20. (a) X; (1 mark)

(b) X has fewer stomata; most stomata in leaf X are concentrated on the lower side; Any one (1 mark)

21. (a) Where different structures evolve to perform the same function (e .g. wings of insects and birds are different in structure but are used for flying);(1 mark)

(b) Missing links;

Distortion of parts during sedimentation/earthquakes/putrefication;

Destruction of fossils by geological activities/faulting/folding;

First two (2 marks)

22. Air that enters lungs has a higher content ofoxygen than air that leaves the lungs; Air that enters the lungs has lower content of carbon (IV) oxide than air that leaves the lungs;(2 marks)

23. (a) (i) Ovule; (1 mark)

(ii) Axile placentation; (1 mark)

(b) Orange or any correctly named citrus plant; » (1 mark)

24. (a) (i) Dominant gene expresses itself phenotypically in both its homozygous and heterozygous states while recessive gene can only express itself phenotypicallj in the homozygous state; (1 mark)

(ii) Continuous variation is a characteristic for which there is a continuum or rang: while discontinuous variation is a characteristic for which there are discrete categories or units; (1 mark)

(b) Either all offspring show the dominant characteristics;

or half offspring show the recessive while the other half show the dominant characteristics; (2 marks)

25. (a) Softening of leather; (1 mark)

(b) Treatment of malaria/manufacture of antimalaria drugs.; (1 mark)

(c) Stimulant used in beverages; (1 mark)

26. egg/ovum/ova; (1 mark)

27. (a) Ligament; (1 mark)

(b) Secretes synovial fluid; contains/holds the synovial fluid in place; any one (1 mark)v 28.

(a) It is a growth movement in plants in response to a unidirectional stimulus; (1 mark)

(b) Accelerates growth of shoots;

Can inhibit growth of roots;(2 mark)

29. Activate enzymes; provides a medium for enzymatic activities to break down stored food to soluble form; Hydrolyses; dissolves food materials; is a medium of transportation of dissolve food substances to growing regions of radicle and plumule; Softens seed coat to facilitate emergence of radicle; First four (4 marks)


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