Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2006PP2QN02
In mice the allele for black fur is dominant to the allele for brown fur. What percentage offspring would have brown fur form across between heterozygous black mice? Show your working. Use letter B to represent the allele for black colour.
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K.C.S.E Biology Q & A - MODEL 2006PP2QN02
Describe the following chromosomal mutations.
a. Inversion b. Translocation.
answers
(i) Occurs when chromatids/ chromosomes break at 2 places and when rejoining the Middle piece rotates and joins in an inverted position.
(ii) Occurs when a section of chromatid break off and becomes attached to another chromatid of another chromosome.
K.C.S.E Biology Q & A - MODEL 2006PP2QN02
Name two disorder in human caused by gene mutation.
answers
K.C.S.E Biology Q & A - MODEL 2006PP2QN01
The diagram below represents bones at a joint found in the hind limb of a mammal.
a) Name the bones labeled XY and Z
b) i) Name the substance found in the place labeled W. ii) State the function of the substance named in (b) (i) above. c) Name the structure that joins the bones together at the joint. d) State the differences between ball and socket joint and the one illustrated in the diagram above. e) Name the structure at the elbow that performs the same function as the same function as the patella.
answers
​(a) X- Femur
Y- Tibia Z- Fibula (b) (i) Synovial fluid (ii) Lubrication of the joint/ shock absorption Distribution of pressure (c) Ligament (d) Ball and socket joint allows movement in all planes while the illustrated allows movement in one plane only. Accept 3600 for all planes 1800 for one plane. (e) Olecranon process. K.C.S.E Biology Q & A - MODEL 2006PP1QN23
State the function of each of the following parts of human ear.
a) Ear ossicles b) Cochlea c) Semi circular canals d) Eustachian tube.
answers
K.C.S.E Biology Q & A - MODEL 2006PP1QN22
State two functional differences between the rods and cones in the human eye.
answers
Rodes Cones
K.C.S.E Biology Q & A - MODEL 2006PP1QN22
State the function of ciliary muscles in the human eye.
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN21
The diagram below represents a reflex are in human.
​a) Name the parts labeled X and Y
b) Name the substance that is responsible for the transmission of an impulse across the synapse.
answers
​(a) X- motor neurone- accept of motor neurone rej. Axon alone
Y- Sense organ/ receptor (b) Acetyl; chlorine/ noradrenaline ( Nerepinephrine)
K.C.S.E Biology Q & A - MODEL 2006PP1QN20
State three biological importance of tropisms plants.
answers
K.C.S.E Biology Q & A - MODEL 2006PP1QN20
What name is given to response to contact with surface exhibited by tendrils and climbing stems in plants?
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN15
Explain continental drift as an evidence of evolution.
answers
​Current continents existed as one large land mass/ Pingea/ Laureshia Guondaland; the present continent drifted leading to isolation of organisms; organism in each continent evolved along different lines hence emergence of new species,
K.C.S.E Biology Q & A - MODEL 2006PP1QN10
State the important of tactic response among some members of kingdom protista.
answer
K.C.S.E Biology Q & A - MODEL 2005PP1QN19
How is the human eye adapted to its function?
answers
Adaptations of the eye.
The presence of:-
K.C.S.E Biology Q & A - MODEL 2005PP1QN12
In a garden with plants of same species, 705 plants had red flowers while 224 had white flowers.
a) Work out the ratio of red to white flowered plants b) (i) Using letter R to represent the dominant gene, work out a cross between F1 offspring and a white flowered plant. (ii) What is the genotypic ratio from the cross in b(i) above? c) What is meant by the term allele? K.C.S.E Biology Q & A - MODEL 2005PP1QN04
What is meant by
a) Organic evolution b) Continental drift?
ABSWERS
​a)It is the process through which ancient simpler forms of life under went gradual series of small changes for many million years, to give rise to the modern species of life // accepts as a theory formed one large single land mass, which later broke up into parts which drifted from one another forming the present day continents.
K.C.S.E Biology Q & A - MODEL 2005PP1QN01
Apart from hearing, state another function of the human ear.
ANSWER
K.C.S.E Biology Q & A - MODEL 2004PP1QN14
What is meant by the following terms? Give an example in each case.
i) Homologous structures ii) Example iii) Vestigial structures Example
answers
​(i) Have a common ( embryonic) origin modified to perform different functions; vertebrae for limb/ pentadactyl limb
Example Vertebrate fore limb/ pretadactyl limb; acc beaks of birds ( fee of birds/ mouthparts in insects. (ii) Have different (embryonic) origins ( but have evolved) to perform similar functions. (iii) Are greatly reduced in size and therefore caused to function Acc. Third digit of wing of bird Halteres in flies Presence of hind limb ( buds) in python Human ear muscles Example Human appendix / kiwi ( flightless bird) with reduced wings/ vestigial wings in flies human hair/ presence of hind limbs in python; reduced pelvic girdle of whale.
K.C.S.E Biology Q & A - MODEL 2004PP1QN14
What is the difference between Darwinian and Lamarckian theories of evolution?
answers
Lamarckian
Inheritance of acquired characteristics/ Environment induces production of inheritable character which is then inherited.while Darwinian Inheritance of genetically acquired characteristics/ character happens to appear spontaneously which then gives advantage to organisms therefore better- adaptable characters are then inherited by natural selection. K.C.S.E Biology Q & A - MODEL 2004PP1QN12
Across between a red flowered plant and white flowered produced plants with pink flowers.
Using letter R to represent the gene for red colour , and W for white colour a) What were the parental genotypes b) Workout a cross between F1 plants c) Give the i) Phenotypic ratio of F2 plants ii) Genotypic ratio of F2 plants d) Name a characteristic in humans, which is controlled through a mammalian heart?
answers
(a) RR WW
(b) Parental genotypes R W Gametes R W X WW R W Fertilization Offsprings RR RW RW WW (c) (i) Phenotypic ration Red Pink White 1 2 1 (ii) 1RR : 2RW; 1WW (d) (ABO) blood grouping; blood groups; K.C.S.E Biology Q & A - MODEL 2004PP1QN06
The diagram below shows the position of an image formed in a defective eye.
​a) Name the defect:
b) Explain how the defect named in (a) above can be corrected
answers
a) Myopia/ shortsightedness / short sight
b) Concave lens / divergent lends; to diverge the rays so that the image is focused on the retina Acc. Concave.
K.C.S.E Biology Q & A - MODEL 2004PP1QN01
State the function of the cartilage named in (a) above
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN01
Name the cartilage found between the bones of the vertebral column
answer
K.C.S.E Biology Q & A - MODEL 2003PP1QN18
Describe the functions of the various parts of the human eye.
answers
Sclerotic layer – (made up of collagen fibres thus) protects the eye maintains shape of eyeball.
Cornea
Eyelids
Lens – Refracts light rays / focuses light on retina Vitrerous aqueous humour once. Aqueous Humour – Nourishes cornea / lens Refracts light Irus – ( pigmented thus) – gives the eye its colour / absorbs light controls amount of light entering the eye / adjusts size of pupil impulses. Pupil – light enters the eyes through pupil. Retina – has photoreceptor cells / rods / cones / image formation ;l generates impulses. Fever / yellow spot – visual acuity / most sensitive part of retina with only cones. Blind spot – point where nerve fibre emerges from the optic nerve / where the optic nerve leaves the eye / point where blood vessels & nerve fibres enter the eye. Optic nerve – transmit impulses to brain. K.C.S.E Biology Q & A - MODEL 2003PP1QN15
A response exhibited by a certain plant tendril is illustrated below.
​a) i) Name the type of response
ii) Explain how the response named in (a)(i) above occurs b) What is the importance of tactic responses to microscopic plants? c) State four applications of plant hormones in agriculture.
answers
a) i) Thigmotropism / haptotropism
ii) Contact with support; causes migration of auxine to enter the side; causing faster growth on the side away from centre of surface (causing tendrils curl around support.) b) Escape injurious stimuli / seek favorable habitats; move towards light / stimuli. c) Induce foot growth in stem cutting
K.C.S.E Biology Q & A - MODEL 2003PP1QN12c
In Drosophila Melanogaster, the inheritance of eye colour is sex – linked. The gene of red eye is dominant. A cross was made between a homozygous red – eyed female and a white – eyed male. Work out the phenotypic ration of F1 generation. (Use R to represent the gene for red eyes).
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