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Biology paper 1 ms MBOONI WEST SUB – COUNTY JOINT EXAMINATION 2013 BIOLOGY PAPER 1 MARKING SCHEME 1. (a) Mitochondrion; (Reject mitochondria) (1mk) (b) Golgi bodies/Golgi apparatus; (1mk) 2 (a) Habitat –A specific locality/place (with a particular set of conditions) where organisms live; Ecological niche- Is a position that an organism occupies in a habitat/food chain /feeding relationship; 3. Maintains salt- water balance/osmotic pressure to optimum levels; in the body tissues /fluids; that is favourable to normal functioning of cells; 4. It has a large surface area exposed to its aquatic environment; gaseous exchange is therefore by (simple) diffusion across its membrane; (2mks) 5. (a) Dicotyledonae; (1mk) (b) Centrally placed star shaped Xylem with phloem (alternatively) between the arms of the Xylem; (b) is tired to (a) (1mk) (c) 6. (a) Numerous/Elongated to increase surface area for absorption of water/minerals/both; Thin walled for faster absorption of water/mineral salts/or both; Numerous mitochondria to provide energy for absorption of mineral salts; Large sap vacuole to create high osmotic pressure; Any one correct 1x1 =1mk Semi- circular canalsMaintenance of body balance and posture; (1mk) (b) Eustachain It equalizes air pressure in the outer and middle ear to prevent distortion of the ear drum/tympanic membrane; (1mk) 7. (a) Epicotyl; (1mk) (b) - It enables the seedling to be firmly anchored in the ground; - It enables the seedling to obtain water and mineral salts; (2mks) 8. Due to increased carbon (IV) oxide/green house gases; The atmosphere forms a layer which prevents escape of terrestrial/ground radiation into the outer atmosphere; heat is therefore retained in the lower atmosphere; This results in increased atmospheric temperatures hence global warming; (3mks) 9. (a) Femur (1mk) (b) (i) K – Pelvic girdle/ innominated born; (1mk) (Reject the fused bones); (ii) L – Tibia; Accept Tibia and fibula. Reject Fibula and tibia. 10. (a) Deamination; (1mk) (b) Removal of excess amino acids; - Availing energy in the body; - Formation of glycogen/fat for storage; (any 2 correct 1x2 =2mks) (b) is tired to (a) 11. (a) Photosynthesis; (b) Carbon (IV) oxide concentration; (the valency power correctly) Temperature; Amount of chlorophyll; (b) is tired to (a) (Any two correct 1x2 =2mks) 12. Y - Chromosome – Tuft of hair from the pinna/ premature baldness; (1mk) X – Chromosome – Colour blindness/Haemophilia; Duchenne muscular dystrophy; (1mk) Mbooni west joint exam 1|P a g e Biology paper 1 ms 13. (a) A rat is endothermic/homoithermic; It requires more energy to maintain; Its body temperature constant ;unlike a lizard which is exothermic/poikilothermic; hence uses environmental heat to generate body temperature; 14. (a) Magnification = Eye piece lens maginification X objective lens magnification; X 450 = X45; X 10 (Reject if 45X is absent missing) The working should be seen for the answer to score (b) Use to bring an image (of a specimen) into sharp focus; 1mk 15 Skeletal muscles Smooth muscles (i)Multinucleated. Uninucleated; (ii)Striated/stripped. Not striated/not stripped; (iii)Long(muscles)fibres. Short(muscle)fibres; (iv)In blocks/cylindrical(in shape) Spindled shaped. Any two 2x1 = 2mks 16.(It facilitates the) reabsorption of useful substances in the kidney tubules into the blood stream; - (It facilitates the) absorption of digested food from the gut into the blood stream; - (It helps in the) movement of waste products from body into the blood stream/excreation of waste products from the body cells into the blood stream; (Any first two correct 2x1 = 2mks) 17. Beneficial characteristic are retained/ because; (i) New offspring are identical to the parent; (ii) Organism matures faster; (iii) It does not depend on population/fertilization/fruit and seed dispersal; (iv) New plants obtain nourishment from their parent plant/ hence they can survive temporarily during unstable environmental conditions; (Any first three correct 3x1 = 3mks) 18. a) Entamoeba histolytica; (rules of Binomial nomeclacture followed) (1mk) b) (i) Proper (sanitary) disposal of faeces and urine/use of deep pit latrines/flash toilets for disposal of faeces and Urine; (ii) All drinking water boiled/chemically treated to kill the eggs/miracidia/cercariae; (iii) People should not bath/swim in water infested with snails; (iv) People should wear protective shoes/water proof shoes/gumboots when walking in waters infested with snails/swampy areas; (v) Spray water infested with snails with molluscicides; (Any first three correct 3x1 = 3mks) 19. (a) (i)Trachea; (1mk) (ii)Diaphragm; (1mk) Reject wrong spelling (b) The ballons will inflate;There will be an increase in volume and a decrease in pressure in the bell jar; and air will fill the balloons;/Air enters the balloons; (Total 3mks max... 2mks) 20. (a) A situation where organisms have homologous structure/structure with common embryonic origin; which is modified to perform different function; to adapt organism to different ecological riches/habitats/due to exploitation of different ecological riches/habitats; (b) It involves combining different breeds of species; resulting to Hybrid vigour/the offspring are better adapted than their parents/Heterosis. (2mks) 21. (a) Sweepnet/insect net; (1mk) (ii) Pooter; (1mk) (b) (i) Unicellular, others colonial/some thalloid; (ii) Are mobile; moving by pseudopodial/cilia/flagella; (iii)Some are heterotrophic while others are autotrophic; Mbooni west joint exam 2|P a g e Biology paper 1 ms Any first two correct (2x1 =2mks) 22. (a) Luteinising hormone; (reject Lh/wrong spelling) (1mk) (b) -Increasing progesterone; inhibits follicle stimulating hormone; from -Stimulating the maturation of another graafian follicle; -Stimulating hormone; 23.Water vapour accumulates in stomatal pits making the environment around the stomata humid; this lowers the saturation deficit;(hence less water is lost into the atmosphere) 24. (a) Prophase I ;(Reject wrong spelling/prophase 1/i) (b) Recombination of genes; leading to variation; (2mks) 25 (a) Herbivorous; (reject t herbivore) (1mk) (ii) Lack of canines/ presence of diastema ; lack of incisors on the upper jaw/has horny pad; (1mk) a (ii) tied to (i) (b) Vitamin B12 /Cobalamine; (1mk) 26. (a) Blood flow at a higher pressure; (since the heart pumps it twice) - Blood flow faster to the tissues; (any one correct 1mk) (b)-Numerous to increase surface area for exchange of materials; -In close contact with the tissues/cells to ensure that every cell is well supplied with nutrients. -Thin walled/one cell thick walled/thin Epithelium for faster exchange of materials; -Narrow lumen to ensure that blood cells have to pass through it inn single file/to enhance ultrafitration; (any two correct 2x1 = 2mks) 27. (a) Abscisic acid; (reject wrong spelling/AbA) (1mk) (b) - Thin walled; numerous mitochondria; -Dense cytoplasm; - No vacuoles; -Small in size; (any first two correct 2x1 = 2mks) 28. It protects the inner delicate tissues; - It prevents dehydration or desiccation; - Provide a surface for attachment of muscle; (which are essential for movement). (any first two correct 2x1 = 2mks) Mbooni west joint exam 3|P a g e