Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2009PP1QN13
Distinguish between diffusion and active transport
ANSWER
In diffusion molecules move from a highly conc. Region to a lowly conc. Region while in active transport molecules move from a lowly concentration region to a highly concentration region; on diffusion molecules move along conc. gradient while in active transport molecules move against conc. gradient. No energy is required in diffusion while energy is required in active transport/ active requires carrier molecules while carrier molecule not required in diffusion;
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K.C.S.E Biology Q & A - MODEL 2009PP1QN12
The diagram below represents a bone obtained from a mammal
​(a) Name the bone
(b) Name the: (i) Bone which articulate with the bone named in (a) above at the cavity labeled K; (ii) Joint formed by the two bones (c) State the function of the part labeled J
ANSWERS
(a) scapula;
(b) (i) Humerus (ii) Ball and socket joint (c) Attachment of muscles K.C.S.E Biology Q & A - MODEL 2009PP1QN11
In an experiment the shoot tip of a young tomato plant was decapitated as shown in the diagram below
​(a) State the expected results after 2 weeks
(b) Give a reason for your answer in (a) above
ANSWERS
(a) auxiliary/ lateral buds spront/ bronches will be formed
(b) Decapitation removes the hormone/ ouxins /IAA which is produced in the terminal bud/ the stem tip; abseul/ removal of the hormone/ auxins/ IAA promote branch/ development of auxiliary lateral buds.
K.C.S.E Biology Q & A - MODEL 2009PP1QN10
Explain why certain drugs become ineffective in curing a disease after many years of use.
ANSWER
K.C.S.E Biology Q & A - MODEL 2009PP1QN10
Give an example of a vestigial structure in human
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN09
Name the disease in humans caused by plasmodium falciparum
ANSWER
K.C.S.E Biology Q & A - MODEL 2009PP1QN09
Name the causative agents of the following diseases in humans
(i) Typhoid (ii) Amoebic dysentery
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN08
What is the role of the testes in the mammalian reproductive systems?
ANSWERS
Pregnancies continues if the ovary of an expectant mother is removed after 4 months explain23/6/2020
K.C.S.E Biology Q & A - MODEL 2009PP1QN08
Pregnancies continues if the ovary of an expectant mother is removed after 4 months explain
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN07
State the function of the following cell organelles
(a) Ribosome (b) Lysosomes
ANSWERS
​(a) site for protein synthesis
(b) Break down worn out cells/ organelles / food materials K.C.S.E Biology Q & A - MODEL 2009PP1QN06
The diagram below shows a section through a plant organ
(a) (i) Name the class of the plant which the section was obtained
(ii) Give a reason for your answer in (a) (i) above (b) State the functions of the part labeled F
ANSWERS
(a) (i) Dicotyledonous; Rej: Dicotyledonous
(ii) Vascular bundles arranged in a ring / presence of vascular (b) (Divides to) give rise to secondary thickening (growth/ increase in growth/ diameter/ width of stem/ gives rise to new/ additional xylem and phloem tissues
K.C.S.E Biology Q & A - MODEL 2009PP1QN05
State two causes of chromosomal mutations
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN05
What is meant by the following terms
(i) Hybrid vigour (ii) Polyploidy?
ANSWERS
(i) production of plants and animals that have superior/ greater productivity/ have beneficial/ characteristics than either of their parents.
(ii) Condition in which an individual has more than two sets of chromosomes K.C.S.E Biology Q & A - MODEL 2009PP1QN04
​The diagram below represents a stage during germination of a seed
​(i) Name the type of germination illustrated in the diagram
(ii) State the role of the part labeled x during germination of the seed
ANSWERS
(i) Epigeal
(ii) Protection of the delicate plumule; pulls the cotyledons above the ground
K.C.S.E Biology Q & A - MODEL 2009PP1QN04
The state during which a seed cannot germinate even when conditions for Germination are suitable is called
ANSWER
K.C.S.E Biology Q & A - MODEL 2009PP1QN03
State the functions of the following parts of a light microscope
(a) Objective lens (b) Diaphragm
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN02
Name two befits that a parasite derives from the host
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN01
State two characteristics of fungi
ANSWERS
K.C.S.E Biology Q & A - MODEL 2009PP1QN01
Name the external feature which is common in birds, fish and reptiles
answer
K.C.S.E Biology Q & A - MODEL 2008PP2QN08
Describe the mechanism of gaseous exchange in a mammal
answers
Breathing in
External intercostals muscles contract; internal, intercostals muscles relax lifting/ raising the ribcage upwards and outwards; muscles of diaphragm contract. It flattens the volume of the thoracic cavity increases; pressure decrease; higher air pressure in the atmosphere forces air into the lungs Breathing out External intercostals/ muscles relax; internal intercostals muscles contract moving the ribcage downwards and inwards; the muscles of diaphragm relax, the diaphragm assumes dome shape; volume of thoracic cavity decreases; while pressure increases; higher pressure forces air out of the lungs
K.C.S.E Biology Q & A - MODEL 2008PP2QN08
State four characteristics of gaseous exchange surfaces
answers
K.C.S.E Biology Q & A - MODEL 2008PP2QN07
Describe the nitrogen cycle
answers
​During thunderstorm/ lightning; nitrogen gas combines with O2 to form nitrogen oxides; nitrogen oxides dissolve in water to for nitric acid; acid is deposited in the soil by rain, nitric acid combines with chemical substance to form nitrates/ nitric acids dissolves to form nitrates which are absorbed by plants symbiotic bacteria/ such as rhizobium; which are found in root nodules of leguminous plants, fix free nitrogen to nitrates.
Free living bacteria/ clatridium/ azotobacteria fix nitrogen to all rates Nostoc algae/ chlorella/ anaemia/ ix nitrogen to nitrates. Plants use Nitrates to form plant proteins Animals feed on plants and convert plant proteins into animal proteins Plants/ animals die and decomposed by bacteria/ saprophytes/ fungi decomposing plants/ animals/ release ammonia which is covered to nitrates/ by nitrosomomes nitrococcus bacteria Nitrates are converted to nitrates; by nitrobacteria Nitrates in the soil can be converted to free nitrogen/ denitrification by some fungi; pseudomonas/ hulobacillus denitrifying bacteria. K.C.S.E Biology Q & A - MODEL 2008PP2QN06
An experiment was carried out to investigate transpiration and absorption of water in sunflower plants in their natural environment with adequate supply of water. The account of water was determined in two hour intervals. The results are as shown in the table below
​(a) Using the same axes, plot graphs to show transpiration and absorption of water in grammes against time of the day
(b) At what time of the day was the amount of water the same for transpiration and absorption? (c) Account for the shape of graph of: (i) Transpiration (ii) Absorption (d) What would happen to transpiration and absorption of water if the experiment was continued till 05 00 hours? (e) Name two factors that may affect transpiration and absorption at any given time (f) Explain how the factors you named in (e) above affect transpiration
answers
​(b) 17.001- 19.99 hrs
(c) (i) Transpiration 1100 – 17000 (rapid) ( in the rate of transpiration) due to high light intensity/ high temperature (ii) 17000 – 0300 hrs decrease (in the rate of transpiration) due to low light intensity/ absence of light/ in temperature. (iii) Absorption 11.00 – 1900 hrs. Increase (in the rate of atmosphere) of water to replace water lost- through transpiration 1900 – 0300 hrs; decrease ( in the rate of absorption of water) due to the fact that rate of transpiration has declined (d) Both transpiration and absorption decrease accept decrease (e) Wind; light, atmosphere pressure, humidity; temperature Temperature - at high temperature the rate is higher/ at low temperature the rate is Low. (f) Wind- rate of transpiration is high when it’s windy/ lower when air still Humidity – when humidity is low, the rate of transpiration is faster/ when its High the rate of transportation is low Pressure- the rate is high at low atmosphere pressure at high atmosphere pressure the rate is low. K.C.S.E Biology Q & A - MODEL 2008PP2QN05
A freshly obtained dandelion stem measuring 5 cm long was split lengthwise to obtain two similar pieces The pieces were placed in solutions of different concentrations in Petri dishes for 20 minutes.
The appearance after 20 minutes is as shown
​(a) Account for the appearance of the pieces in solutions L1 and L2
(b) State the significance of the biological process involved in the experiment
answers
​(a) L1
Inner cells gained water by Osmosis; hence increased in length; epidermal cells did not gain water because they are covered by a water proof cuticle leading to currature. L2 Inner cells lost water by osmosis; leading to (flaccidity) decrease in length; epidermal cells did not lose water due to waterproof leading to currature (b) Support in (herbaceous) plants Absorption of water Opening and closing of stomata Movement of water from cell to cell Leading in infectious plants Folding of leaves in the Mimosa |
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