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K.C.S.E Biology Q & A - MODEL 2007PP2QN08
Describe causes and methods of controlling water pollution
answers
K.C.S.E Biology Q & A - MODEL 2007PP2QN07
Describe the structure and functions of the various parts of the human ear
answers
The ear is an organ involved in perceiving sound and maintaining body balance and posture. It is made of the following sections
Pinna – That is funnel shaped structure made of skin and cartilage. It receives sound waves and directs them to the ear tube. External/auditory meatus – That is a canal lined with air and wax. It allows passage of sound waves to the middle ear. The hairs and wax trap dust particles that enter the ear. Tympanic membrane – That is a thin flexible sheet-like structure receives sound waves and pass the vibration to the ossicles. Middle ear that is composed of Tiny bones known as ossicles – They are anvil and incus. They amplify vibration from the tympanic membrane. Eustachian tube – That connects the ear to the nasal cavity. It balances pressure on both sides of the tympanic membrane. Oral window – That is a thin flexible membrane that opens into the inner ear. it receives vibrations from the ossicles and passes them to the inner ear. Inner ear that is compost of; Vestibular apparatus- That are the semicircular canals, utricles and saccules. They help in maintenance of body balance and posture. Cochlea – That is a coiled structure that has sensory cells for hearing. It connected to the auditory nerve that is involved in transmission of sounds to the brain
K.C.S.E Biology Q & A - MODEL 2007PP2QN06
Other than sugars name two compounds that are translocated in phloem
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K.C.S.E Biology Q & A - MODEL 2007PP2QN06
Name the structures in phloem that are involved in the translocation of sugars
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K.C.S.E Biology Q & A - MODEL 2007PP2QN06
In the experiment to determine the effect of ringing on the concentration of sugar in phloem a ring of bark from the stem of a tree was cut and removed. The amount of sugar in grammes per 16cm3 piece of bark above the ring was measured over a 24 hour period. Sugar was also measured in the bark of a similar stem of a tree which was not ringed. The results are shown in the table below.
(a) Using the same axes, plot a graph of the amount of sugar against time
(b) At what time was the amount of sugar highest in the (i) Ringed stem (ii) Normal stem? (c) How much sugar would be in the ringed stem if it was measured at 0345hours? (d) Give reasons why there was sugar in the stems of both trees at 06 45 hours (e) Account for the shape of the graph for the tree with ringed stem between: (i) 06 45 hours and 15 45 hours (ii) 15 45 hours and 00 45 hours
answers
(b)(i) 15: 45
(ii) 12:45 (c) 0.79 + 0.02 grammes (d) The food that had been manufactured the previous day had been converted to soluble sugars and was being translocated to other parts of the plant. (e)0645 hours and 15 45 hours There was low concentration of sugars early in the morning as there was little translocation As day progresses the light intensity increases and more food is manufacture thus more translocation increasing concentration of sugars (ii)15 45 hours and 0045 hours The light intensity is decreasing reducing rate of photosynthesis. Less food is manufactured hence less is translocation As it turns dark there is no photosynthesis reducing concentration of sugars translocated.
K.C.S.E Biology Q & A - MODEL 2007PP2QN05
What is meant by hybrid vigour?
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K.C.S.E Biology Q & A - MODEL 2007PP2QN05
What is genetic engineering?
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K.C.S.E Biology Q & A - MODEL 2007PP2QN05
In maize the gene for purple colour is dominant to the gene for white colour. A pure breeding maize plant with purple grains was crossed with a heterozygous plant.
(a) (i) Using letter G to represent the gene for purple colour, work out the genotype ratio of the offspring (ii) State the phenotype of the offspring
answers
(ii) All purple coloured grained maize plants
K.C.S.E Biology Q & A - MODEL 2007PP2QN04
State two advantages of having an exoskeleton
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K.C.S.E Biology Q & A - MODEL 2007PP2QN04.
State the functions of synovial fluid
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K.C.S.E Biology Q & A - MODEL 2007PP2QN04
State the difference between ball and socket and hinge joint
answers
Name the three type of muscles found in mammals and give an example of where each of them is found21/6/2020
K.C.S.E Biology Q & A - MODEL 2007PP2QN04
Name the three type of muscles found in mammals and give an example of where each of them is found
annswers
K.C.S.E Biology Q & A - MODEL 2007PP2QN03
The diagram below shows a stage during fertilization in a plant.
(i) Name the parts labeled Q, R, and S
R S (ii) State two functions of the pollen tube (c) On the diagram label the micropyle
answers
​(b)(i) Q – Antipodal cells
R- Polar body/ polar nucleaus S – egg cell (ii) Path the rough which the male gametes reach the embryo sac to enhance fertilization (iii) Prevent other pollen grains from developing into pollen tubes hence no multiple fertilization of embryo sac 
K.C.S.E Biology Q & A - MODEL 2007PP2QN03
What is meant by the following terms
(i) Protandry (ii) Self sterility?
answers
(i) Protandry – stamens mature and pollen grains are shed off before the stigma matures
(ii) Self sterility – Pollen grains from the anthers cannot grow on the stigma of the same flower or plant
K.C.S.E Biology Q & A - MODEL 2007PP2QN02
What term is given to the condition described in (c) (i) above
answer
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