Biology 3 Nov/Dec 2013 - Candidates Weakness

Biology Paper 3,Nov/Dec 2013

Questions:		1	2	3	4		Main

General Comments
Weakness/Remedies
Strength

Question 2
The diagram below is an illustration of a biotic community. Study it carefully and use it to answer questions 2(a) to 2(d). (a) (i) Name the biotic community represented in the diagram. [1 mark] (ii) State two characteristic features of the community named in 2 (a) (i). [2 marks] (b) (i) State five abiotic factors that can influence the biotic community named in 2 (a) (i).[5 marks] (ii) Name one instrument each for measuring the abiotic factors stated in 2 (b) (i). [5 marks] (c) (i) State two effects of rainfall on the community. [2 marks] (ii) Name the predominant plant and one animal predator usually found in the community. [2 marks] (d) (i) State two characteristic features each of the plant and animal mentioned in 2 (c) (ii). [4 marks] (ii) State two ways by which each of the plant and animal mentioned in 2 (c) (ii) are adapted to the environment.
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OBSERVATION
Few candidates were able to name the biotic community correctly and state the characteristic feature. Candidates correctly named biotic factors and instruments used to measure them. Many candidates performed poorly in listing the adaptation of plants and animals. The expected answers are: (a) (i) Name of Community Guinea Savanna/ Savanna/Savannah (ii) Characteristic features of community Plenty grass; scattered/few trees; trees with broad crowns; many herbivores/rodents/named herbivore/carnivore/named carnivore, Guinea fowl, grasshopper. (b) (i) Abiotic factors Rainfall; humidity; temperature; atmospheric pressure; wind; light intensity/sunlight; pH; Soil/Edaphic factors. (ii) Instruments Rain gauge, hygrometer, thermometer, barometer, anemometer, wind vane, pH meter, light meter/photometer. (c) (i) Effects of rainfall - when there is sufficient rainfall grasses grow taller; plenty grass and animals will abound; - heavy rainfall leads to soil erosion/leaching/flooding; - when there is scarcity of rainfall grasses dry up/wither and die; - the animals emigrate/disperse/may die/aestivate. (ii) Name of plant and animal Plant: Grasses/ Elephant grass/Imperata/Guinea grass. Animal: Lion/Hyena/Cheetah/Tiger/Leopard/Praying mantis/Spider/Snake (d) (i) Characteristic features of plant and animal Plant: turfted; underground stems; leaves have thick cuticle and sunken stomata Animal: Presence of canine; good sense of smell/sight/hearing; strong jaws/mandibles; sharp claws/ muscular/powerful/strong limbs/legs. (ii) Adaptations Plant: Small leaves to reduce transpiration; underground stem for quick re-growth after fire/drought. Animal: Muscular legs to run fast; strongly built for agility and speed; long canines and claws to grasp prey/ good sense of smell/sight/hearing to sight prey.