Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN02
Distinguish between natural and acquired immunity
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​K.C.S.E Biology Q & A - MODEL 2003PP1QN19
Describe how fruits and seeds are suited to their modes of dispersal.
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Water dispersed fruit / seeds
K.C.S.E Biology Q & A - MODEL 2003PP1QN17
Some students used a model to demonstrate the effect of sweating on human body temperature. Two boiling tubes A and B were filled with hot water. The temperature of water in the tubes was taken at the start of the experiment and then at 5 minutes interval. The surface of tube A was continuously wiped with a piece of cotton wool soaked in methylated spirit. The results obtained are shown in the table below.
a) On the same axes, plot graphs of temperature of water in the tubes against time.
b) At what rate was the water – cooling in tube A? c) Why was tube B included in the set up? d) Account for the rate of cooling in tube A. e) State two processes of heat loss in tube b. f) What would be the expected results if tube A was insulated? g) What would the insulation be comparable to in: i) Bird ii) Mammals? h) Name the structures in the human body that detect: i) External temperature changes ii) Internal temperature changes
answers
​ b) 80 – 18 = 62; 2.48C /Min
2.5 25 c) Control d) Rate was faster in tube A; because the film of methylated sprit evaporated; removing heat from the tube; e) Convection ; radiation f) Lower rate of heat loss; g) i) birds Feather ii) Mammals? Fur h) i) external temperature changes Temperature ii) Internal temperature changes Hypothalamus
K.C.S.E Biology Q & A - MODEL 2003PP1QN14
Explain the role of antidiuretic hormone when there is excess water in the human body.
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K.C.S.E Biology Q & A - MODEL 2003PP1QN14
Explain how marine fish regulate their osmotic pressure.
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K.C.S.E Biology Q & A - MODEL 2003PP1QN13
The diagram below shows gaseous exchange in tissues.
a) Name the gas that diffuses:
i) To the body cells ii) From the body cells b) Which compound dissociates to release the gas named in (a) (i) above? c) i) what is tissue fluid? ii) What is the importance of tissue fluid? d) Name the blood vessel with the highest concentration of: i) Glucose ii) Carbon dioxide
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​a) i) Oxygen
ii) Carbon dioxide b) Oxyhaemoglobin c) i) The blood plasma except blood cells and proteins; that has filtered out of the capillaries. ii) It is a medium of exchange of substances/ materials between capillaries and body cells; supply nutrients to cells / supply oxygen to cells / remove waste products from cells. d) i) Hepatic portal vein ii) Pulmonary artery K.C.S.E Biology Q & A - MODEL 2003PP1QN09
Name the:
a) Material that strengthens xylem tissue. b) Tissue that is removed when the bark of a dicotyledonous plant is ringed.
answers
a) lignin
b) Phloem
K.C.S.E Biology Q & A - MODEL 2003PP1QN03
How do the male gamete nuclei reach the ovule after pollen grains land on the stigma?
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K.C.S.E Biology Q & A - MODEL 2003PP1QN01
A process that occurs in plants is represented by the equation below.
C6H12O6 2C2H5OH + 2CO2 + Energy (Glucose) (Ethanol) (Carbon dioxide) a) Name the process. b) State the economic importance of the process named in (a) above
answers
a) Anaerobic respiration / fermentation; Acc. Alcohol production/ drawing dough.
b) Brewing/ Banking. K.C.S.E Biology Q & A - MODEL 2002PP1QN16
The diagram below represents part of phloem tissue.
​a) Name the structures labeled R and S and the cell labeled T.
R S Cell labeled T b) State the function of the structure labeled S c) Explain why xylem is a mechanical tissue
answers
​(a) R. Sieve pore
S- cytoplasmic strand, cytoplasmic filaments rej. Proto plasmic strand) Cell labeled T (b) Translocation (L is tied with structures) (c) Thickened and lignified.
K.C.S.E Biology Q & A - MODEL 2002PP1QN09
Name two gaseous exchange structures in higher plants.
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K.C.S.E Biology Q & A - MODEL 2002PP1QN06
In what form is oxygen transported from the lungs to the tissues?
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K.C.S.E Biology Q & A - MODEL 2002PP1QN03
State the function for co-factors in cell metabolism
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K.C.S.E Biology Q & A - MODEL 2001PP1QN15
The diagram below represents a set up to investigate the conditions necessary for seed germination.
The set up was left for 7 days
(a) What conditions were being investigated in the experiment? (b) State three reasons for soaking seeds in set ups A and B (c) What were the expected results after seven days?
answers
(a) water, temperature moisture (Acc. Warmth)
(b) Mobilize/ hydrolyze stored food/ active enzymes/ breaking of dormancy softening the testa / seed coat ( acc. As a solvent/ transport media.) (c) Setup A – those in set up A will germinate Setup B- those in set up B will not germinate Setup C- those in set C will not germinate K.C.S.E Biology Q & A - MODEL 2001PP1QN11
The diagram below represents a mammalian nephron
(a) Name the
(i) Structure labeled P (ii) Portion of the nephron between point X and Y (b) Name the process that takes place at point Q (c) Name one substance present at point R but absent at point S in a healthy mammal (d) The appearance of the substance you have mentioned in (c) above is a symptom of a certain disease caused by a hormone deficiency. Name the (i) Disease (ii) Hormone (e) State the structural modifications of nephrons found in the desert mammals
answers
(a) (i) Efferent arteriole/ vessels
(ii) Loop of henle (b) Ultra – filtration ( acc. Pressure filtration) rej. Filtration (c) Glucose ( acc. Blood sugar) (d) (i) Disease – diabetes mellitus ( acc. Sugar diabetes) (ii) Hormone – insulin (e) Small Bowman’s Capsule/ Groleruli`; Rej few Bowman’s capsule Loop of Henle
K.C.S.E Biology Q & A - MODEL 2001PP1QN10
Name three sites where gaseous exchange takes place in terrestrial plants.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2001PP1QN08b
Name the blood vessel that transports blood from:
(i) Small intestines to the liver (ii) Lungs to the heart
ANSWERS
(i) Hepatic portal vein
(ii) Pulmonary vein A person whose blood groups is AB requires a blood transfusion. Name the blood groups of the donors.16/6/2020
K.C.S.E Biology Q & A - MODEL 2001PP1QN03
A person whose blood groups is AB requires a blood transfusion. Name the blood groups of the donors.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2000PP1QN15
The concentration of the lactic acid in blood during and after an exercise was determined. The results are shown in the graph below
(a) (i) By how much did the lactic acid increase at the end of 13 minutes?
(ii) After how many minutes was the lactic acid concentration 71mg/100cm3? (iii) What would be the concentration of lactic acid at the 60th minute? (b) Give a reason for the high rate of production of lactic acid during the Exercise (c) Give a reason for the decrease in the concentration of lactic acid after the exercise
answers
​(a) (i) 78/78 mg/ 100cm3
(ii) 8.5th and 29.5th / 8min 30 sec and 29 min 30 sec (iii) 47 mg/100cc; Acc. 47 (b) The demand for oxygen is more than the supply leading to anaerobic respiration. Acc. Lactic acid converted to glucose/Glycogen (c) Lactic acid is oxidized ( to form CO2 and H2O) Acc. Lactic acid is converted to glucose/ glycogen K.C.S.E Biology Q & A - MODEL 2000PP1QN13
The temperature of a person was taken before, during and after taking a cold bath. The results are shown in the graph below
(a) Explain why the temperature fell during bath
(b) What changes occurred in the skin that enabled the body temperature to return to normal?
answers
​(a) Heat loss by conduction/ convection from the blood vessels
The body skin to the cold water, the cooler blood leaving skin enters general circulation cooling the whole body. (b) Vasoconstriction; thus less blood flowing to the skin reducing heat loss. Sweating eases heat produced through metabolism Accept shivering producing heat K.C.S.E Biology Q & A - MODEL 2000PP1QN11
The diagram below represents a section of a leaf.
(a) Name the parts labeled X, and Y
(b) Using arrows indicate on the diagram the direction of flow of water during the transpiration stream (c) State two ways in which the leaf is suited to gaseous exchange
answers
​(a) X– Spongy mesopyll ( cell) layer
(b) Y – Cuticle (c) Broad/ flat leaf ( lamina) to provide large surface area or absorption of gases Thickness: allow gases to pass though fast Presence of stomata for efficient diffusion of gases Presence of air spaces for easy defuses
K.C.S.E Biology Q & A - MODEL 2000PP1QN09
State two advantages of metamorphosis to the life of insects.
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K.C.S.E Biology Q & A - MODEL 1999PP1QN16
Describe the:
a) Process of inhalation in mammals. b) Mechanisms of opening and closing of stomata in plants.
answers
a) Muscles of diaphragm contract; causing the diaphragm to flatten (from dome position. The external intercostals muscles contract internal intercostals muscles relax pulling the ribcage upward/forward and outward in man. These movements increases the volume of the thoracic cavity; reducing the pressure; of the thoracic cavity; compared to atmospheric pressure; this causes the atmospheric air to rush into the lungs. (Through the nostrils, trachea bronchioles and alveoli).
b) Theory- photosynthesis Guard cells have chloroplasts; in the presence of light; photosynthesis occurs in guard cells, producing sugar in guard cells; osmotic pressure increases/osmotic potential lowers; water from neighboring /adjacent cells enter into guard cells; causing turgidity of guard cells; causing turgidity of guard cells. Theory 1. Guard cells have chloplasts; in the presence of light photosynthesis occur in the guard cells of stomata; producing in the guard cells; osmotic pressure increases/lowers osmotic potential water from the neighboring /adjacent cells, enter into guard cells; causing turgidity of guard cells The inner walls of the guard cells are thicker than outer walls; so during turgidity the inner walls stretch more; causing the guard cells to bulge outward; stomata opens. Theory 2. Guard cells have chloroplasts (Day) in light; photosynthesis occurs in the leaf/guard cells lowering the CO2 concentrations; this increases PH/alkalinity which triggers of enzymatic conversion of starch to sugar (glucose); leading to low osmotic potential/ increased osmotic pressure in guard cells; guard cells absorb water from epidermal cells; thus becoming turgid; the inner walls are thicker than the outer walls; outer walls stench more than inner walls; causing guard cells to bulge outwards, stomata opens; In the absence of light (night); no photosynthesis; CO2 concentration increases due to respiration; PH lowered/ acidity increases; sugar converted to starch; osmotic pressure lowered/ osmotic potential increases; guard cells lose water to adjacent epidermal cell becoming flaccid; stomata close. Day low H+ high PH opens stomata. Starch glucose. Theory 3 Guard cells have chloroplasts; in light AT produced; the energy drives K+ irons from adjacent epidermal cells into guard cells; accumulation of K+ raises osmotic pressure (lower osmotic potential) of guard cells; guard cells absorbs water from adjacent epidermal cells; becoming turgid; the inner walls are thicker than the outer walls so outer walls stretch more than inner walls causing guard cells to bulge outward. Stomata opens. In the absence of light (night ) ATP rapidly decreases; no energy of potassium +ions pump ion; migrate by diffusion from guard cells to adjacent epidermal cells; become flaccid; the thinner outer walls of guard cells shrink K.C.S.E Biology Q & A - MODEL 1999PP1QN11
Give reasons for each of the following:
a) Constant body temperature is maintained in mammals. b) Low blood sugar level is harmful to the body.
answers
​a) Most enzymes in the body function within a narrow range of temperature;
High temperature denature enzymes Low temperature inactive /inhabit enzymes b) Sugar in a raw material for respiration, hence less energy, available to body/low/rate of metabolism.
K.C.S.E Biology Q & A - MODEL 1999PP1QN02
Give two reasons why accumulation of lactic acid during vigorous exercise leads to an increase in heartbeat.
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