K.C.S.E Biology Q & A - MODEL 2013PP2QN02
The diagram below represents the human ear.
​(a) Name the parts labelled E, F and G.
E F. (b) How is each of the following adapted to its function? (i) External auditory meatus; (ii) Ear ossicles. (c) Name one defect of the human ear.
answers
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K.C.S.E Biology Q & A - MODEL 2013PP1QN29
State two functions of pelvic girdle in mammals.
answers
K.C.S.E Biology Q & A - MODEL 2013PP1QN28
Name the bone that allows the head to:
(i) nod; (ii) turn side ways
answers
​(i) Atlas;
(ii) Axis allows movement in all planes;
K.C.S.E Biology Q & A - MODEL 2013PP1QN28
State two features of a ball and socket joint.
answer
K.C.S.E Biology Q & A - MODEL 2013PP1QN26
Name two sex linked traits in human beings.
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K.C.S.E Biology Q & A - MODEL 2013PP1QN26
What is meant by the term sex linked genes?
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K.C.S.E Biology Q & A - MODEL 2013PP1QN23
The diagram below illustrates a defect in the eye.
Explain how the defect illustrated above can be corrected.
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K.C.S.E Biology Q & A - MODEL 2013PP1QN22
The diagram below illustrates a response by a certain plant.
​(a) Name the type of response.
(b) Explain how the response illustrated above occurs.
answers
​(a) Thigmotropism/Haptotropism;
(b) Part of the tendril in contact with support causes migration of auxins to the opposite side; leading to faster cell division/growth on the side not in contact with the support: This causes the tendril to curl around the support;
K.C.S.E Biology Q & A - MODEL 2013PP1QN21
What is meant by the term organic evolution?
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K.C.S.E Biology Q & A - MODEL 2013PP1QN21
Explain the role of continental drift in evolution.
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K.C.S.E Biology Q & A - MODEL 2013PP1QN20
Explain the theory of evolution by natural selection.
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K.C.S.E Biology Q & A - MODEL 2012PP2QN07
Using a relevant example in each case, describe simple and conditional reflex actions.
ANSWERS
Simple reflex action - withdrawal of finger from a sharp object.
Is an automatic response to a specific stimulus; When the finger touches a sharp object, pain receptors in the skin; are stimulated and trigger off a nerve impulse; The nerve impulse is transmitted via the sensory neuron; to the grey matter of the spinal cord; The impulse is then transmitted via a synapse; to the relay neuron; and then through another synapse; to the motor neuron; The impulse is then transmitted to the effector muscles in the hand; These effector muscles contract; and the finger is withdrawn from the hot object; Conditioned reflex action Is an automatic response evoked from an animal by unrelated stimulus; substituted for the one which normally elicits the response; It develops from past experience; and involves modification of behaviour through learning; It weakens with time; and must be reinforced by repeating the unrelated stimulus; Students salivate when the bell for lunch rings; because they have learned to associate the ringing of the bell at lunchtime with food; from experience; every time it rings, they are offered food; K.C.S.E Biology Q & A - MODEL 2012PP2QN04
The diagram below illustrates arrangement of bones and muscles of the human arm.
​(i) Name the bones labelled K and L.
K L (ii) Explain how the upward movement of the lower arm is brought about by the, bones and muscles shown in the diagram above. (b) State three ways in which support is brought about in a leaf.
answers
​(a) (i) K - ulna;
L - humerus; (ii) movement of the lower arm upwards takes place at the elbow/olecranon process which is between the ulna and the humerus; biceps/flexor muscles contract; while the triceps/extensor muscles relax; bringing about the movement of the lower arm upwards. , (b) The rigid midrib holds leaf out away from the stem; Profuse network of veins have lignified cells which support leaf to stay spread out; Turgidity in spongy mesophyll and palisade cells support the leaf to remain open; K.C.S.E Biology Q & A - MODEL 2012PP2QN01
In a certain plant species which is normally green, a recessive gene for colour (n) causes the plants to be white in colour. Such plants die at an early age. In the heterozygous state, the plants are pale green in colour but grow to maturity.
(a) Give a reason for the early death of the plants with the homozygous recessive gene. (b) If a normal green plant was crossed with the pale green plant, what would be the genotype of the first filial generation (F1 generation)? Show your working. (c) If heterozygous plants were self-pollinated and the resulting seeds planted, work out the proportion of their offspring that would grow to maturity. K.C.S.E Biology Q & A - MODEL 2012PP1QN26
(a) State the theories of evolution proposed by the following scientists.
(i) cell organelles (ii) fossils
answers
​(a) Theory of natural selection;
Theory of environmental influence on inherited characteristics; (b) (i) Similar organelles performing similar functions in different organisms suggest a common ancestry/cell biology; (ii) Fossil records/palaeontology/by comparing fossils to show phyllogenetic relationship between organisms/common ancestry;
K.C.S.E Biology Q & A - MODEL 2012PP1QN22
State the importance of divergent evolution to organisms.
answer
K.C.S.E Biology Q & A - MODEL 2012PP1QN11
Name the muscles found in the following organs:
stomach; bone
answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN09
State the importance of negative phototaxis to termites.
answer
What is the probability of a couple with blood group AB getting a child with blood group AB?26/6/2020
K.C.S.E Biology Q & A - MODEL 2012PP1QN08
What is the probability of a couple with blood group AB getting a child with blood group AB?Describe how accommodation in the human eye is brought about when focusing on a near object.25/6/2020
K.C.S.E Biology Q & A - MODEL 2011PP2QN08
Describe how accommodation in the human eye is brought about when focusing on a near object.
answers
Light rays from a near object are more diverged and need to bend more; in order to be focused properly on the retina; ciliary muscles contract; suspensory ligaments attached to the ciliary muscles relax; the lens becomes thicker; increasing its curvature/becomes more convex; light from the object is refracted more; in order to be focused/more sharply on the retina to form an image.
K.C.S.E Biology Q & A - MODEL 2011PP2QN08
Describe the exoskeleton and its functions in insects.
answers
The exoskeleton is made of chitin; chitin is not evenly distributed; hence it allows for movement; exoskeleton is secreted by the epidermal cells; when still soft it allows for growth of the insect; when in contact with the air it hardens limiting growth; It is shed regularly; thus regulating the growth of insects. It also supports the internal structures; Because it is hard; it protects; internal organs from mechanical damage. It is water proof; preventing water loss/dessication; of the insect. It also provides a surface for attachment of muscles;
K.C.S.E Biology Q & A - MODEL 2011PP2QN04
The diagram below represents a section of the human brain.
(i)Name the structures labelled P and R.
P R (ii) State two functions of the part labelled Q. (b) (i) Name two reproductive hormones secreted by the pituitary gland in women. (ii) State one function of each of the hormones named in (b)(i) above.
answers
(a) (i) - is cerebral hemisphere/cerebrum;
R - medulla oblongata; (ii) Muscular co-ordination; maintaining body posture; manual/motar dexterity; (b) (i) Follicle stimulation hormone; luteinizing hormone; oxytocin; prolactin; (ii) FSH - stimulates secretion of oestrogen; stimulates development of the Graafìan follicle; LH - Brings about ovulation; causes development of corpus luteum; Oxytocin - causes contraction of uterus; causes expulsion of milk from mammary glands; Prolactin - stimulates milk production/secretion;
K.C.S.E Biology Q & A - MODEL 2011PP2QN02
Explain how comparative embryology is an evidence for organic evolution.
answer
K.C.S.E Biology Q & A - MODEL 2011PP2QN02
Name two disorders in humans that are determined by sex-linked genes.
answers
K.C.S.E Biology Q & A - MODEL 2011PP2QN02
In humans, hairy ears is controlled by a gene on the Y Chromosome.
(a) Using letter Y^H to represent the chromosome carrying the gene for hairy ears, work out a cross between a hairy eared man and his wife. (b) (i) What is the probability of the girls having hairy ears? (ii) Give a reason for your answer in (b(i) above. |
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