KCSE Past Papers 2010 Biology Paper 1 (231/1)

Biology 2010 Paper 1 (231/1)

1. (a) Cytology: Rej cell biology
(b) Microbiology

2. (a) Stem
(b) i) Monocotyledonae
ii) Vascular bundles scattered not arranged in a ring; Absence of pith; Absence of vascular cambium.
(c) Epidermis

3. (a) Protein synthesis (Accept: site for protein symbiosis)
(b) Destroys worn out organelles/cells/tissues
Destroys micro-organisms.

4. (a) i) Root hair(cell)
ii) D – cell wall
E – cell sap (vacuole)
(b) Controls the functioning of the cell/ controls cell activities

5. A large surface area for efficient diffusion of gases
Moist for gases to diffuse in solution form/to dissolve gases
Thin for efficient/diffusion of gases (across a short distance)
Most be close to body cells/well supplied with blood vessel to active cells
Ventilation mechanism for bringing in air rich in O2 and expelling air rich in carbon(iv) oxide

6. (a) Maintain balance/posture/control/muscular movement
(b) Control heart beat/ blood pressure/ breathing(rate) control involuntary activities/ response
Accp. Curved examples of v.a e.g. eating, swallowing e.t.c.

7. Haemolysis – process by which red blood cells take in water till they burst;
while Plasmolysis – loss of water from plant cells until the cell membrane is detached from the cell wall/ until the cell become flaccid.

9. – They contain chlorophyll which traps/absorb light (energy)
– They have grana which increase surface area for accommodation of a large number of chlorophyll molecules for photosynthesis
– The stoma has enzymes for photosynthesis

10. – Resistance to diseases/pests/adverse weather conditions (Acc. Correct examples e.g. drought, very high/ low temperatures
– Increased yields
– Earlier maturity Acc. Early maturity

111. (a) Aquatic / fresh water
(b) Large air space/aerenchyma Sclereids
Stomata on upper epidermis/absence of stomata in lower epidermis
Absence of cuticles
Poorly developed vascular bundles

12.(a) J – sporangium
(b)- Absorption of soluble substances/ digested food
– Secretion of digestive enzymes;
– Anchorage(of mould on substrate); anchorage must be in the right context

13. (a) Place/environment in which (specified)organism lives
(b) A natural unit with abiotic and biotic factors

14. Charcoal in limited supply of air produces carbon(ii)oxide; which combines with haemoglobin forming carboxyhaemoglobin; which is stable/ does not dissolve reducing capacity of the haemoglobin leading to suffocation/ death;

15. a) X – Starch present
Y – Starch absent
b) X – acts as a control; Y – CO2 absent absorbed by potassium hydroxide pellets; Acc correct explanation

16. Emulsification / breaking down of fats into (tiny) droplets
Creating alkaline medium for digestive enzymes/ neutralizing acidic chyone (from the stomach)

17. (a) Herbivorous; Rej Harbivores
(b) Lack canines/ incisors on upper jaws

18. Animal form waste products more rapidly than plants/ Produce more metabolic wastes
Animals don’t reuse their waste while plans reuse some of their wastes;

19. When temperature is high they dilate; when low they constrict (Acc. Vasodilatation)

20. Higher chances of fertilization
Embryo/gamete is protected from external environment conditions

21. (a) P – sutures
(b) i) Atlas;
ii) Hinge joint

22. (a) Passage of ova/ site of fertilization
(b) Storage of sperms
(c) Hold the testis/ protect the testis

23. – Absence of nucleus, increase of space for packaging haemoglobin(for carrying oxygen)
– Possession of haemoglobin which has high affinity for oxygen
– Bi-concave shape creates large surface area for combining with oxygen
– Ability to change shape/flexible to enable them pass through capillaries.
– Have carbonic anhydrate which increase CO2 transportation
– Are numerous/many to be able to carry max amount of oxygen
– Has plasma membrane which allow rapid diffusion of gases

24. (a) Use and disuse
Acquired traits can be passed on to offspring
(b) Acquired characteristics cannot be inherited
No evidence to support the theory

25. – Overcrowding
– Accumulation of toxic wastes
– Limited resources such as nutrients

26. (a) Provide support
Enables plants to grow forward light
(b) In search of nutrients

27. (a) Failure of homologous chromosomes to segregate during meiosis/ anaphase I/ meiosis I Failure of sister chromatid to segregate during meiosis/ anaphase II / meiosis II.
(b) i) Down’s syndrome; Turner’s syndrome; Klinefelter’s syndrome Surnerz syndrome
Acc. Mongolism for Doran’s syndrome
ii) Albinism; single cell anaemia; heamophilia; colour blindness Chondrodytrophic dwarfism/ Achondroplasia

28. Arteries have thick muscular walls; veins have thin and less muscular walls Arteries have narrow lumen, veins have wider lumen Arteries have no valves except at junction with heart; veins have valves at regular intervals.

29. (a) Gymnospermae/ Gymuspermatophyta/ Gymnosperonaphyta;
(b) Needle-like leaves; thick waxy cuticle
Naked seeds; sunken stomata.

30. The inhibition of growth of lateral buds; by auxins; produced by the growing apical bud.

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