Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2014PP2QN03
​(a) Describe the mechanism of gaseous exchange in plants through the lenticels.
(b) Explain each of the following: (i) the tracheoles lack spiral bands of chitin; (ii) the floor of the mouth is lowered during inhalation in a bony fish.
answers
​(a) O2, concentration is higher outside than inside the lenticels; O2, diffuses into lenticels; then into the cells; CO2 concentration is higher inside the lenticels than on the outside CO2 diffuses out of the lenticels into the atmosphere;
(b) (i) To provide a large surface area! make them thin; for gaseous exchange to reduce diffussion distance for respiratory gases; (ii) This increases the volume of the buccal cavity while decreasing the pressure; which forces water to rush into the mouth;
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K.C.S.E Biology Q & A - MODEL 2014PP2QN02
The diagram below illustrates the role played by red blood cells in the transportation of carbon (1V) oxide.
​(a) Other than the carbon (IV) oxide transportation in the red blood cells, name the other form of carbon (1V) oxide transportation in humans.
(b) (i) Name substance F (ii) Name the enzyme marked C and state its role in the reaction. Enzyme Role (c) Explain why transportation of carbon (1V) oxide in red blood cells is advantageous. (d) Explain the role of calcium ions in blood clotting.
ANSWERS
​(a) Carbonic acid/carbaminohaemoglobin/hydrogen carbonate;
(b) (i) Water; (ii) Carbonic acid; Role: catalyses reaction between carbon IV oxide and water to form (weak) carbonic acid; (c) Prevents accumulation of acidity/maintains pH of blood since hydrogen ions combine with haemoglobin to form Haemoglobin acids; Faster; due to the catalytic effect of carbonic anhydrase; (d) Activates thromboplastin; thrombokinase to neutralize heparin/convert prothrombin to thrombin; K.C.S.E Biology Q & A - MODEL 2014PP2QN01
​(a) State four characteristics of fruits dispersed by animals.
(b) State two roles of each of the following hormones in menstruation: (i) luteinising hormone; (ii) oestrogen.
ANSWERS
​(a)
K.C.S.E Biology Q & A - MODEL 2014PP1QN27
The diagram below shows the gaseous exchange system of a locust.
​(a) Name the structure labelled Q.
(b) State the function of the part labelled R. (c) How is the part labelled S structurally adapted to its function?
ANSWERS
​ (a) Spiracle;
(b) Keep the trachea open for air passage; (c) Lacks spiral bands of chitin /to make it thin; for diffusion of gases; Moist; to dissolve respiratory gases; K.C.S.E Biology Q & A - MODEL 2014PP1QN26
The table provided shows the concentration of sodium and iodine in sea water and cell sap of a plant.
​(a) (i) Name the process through which the plant cells take up sodium ions.
(ii) Give a reason for your answer in (a) (i) above. (b) If the plant was sprayed with a chemical that inhibits respiration: (i) which of the two ions uptake will be affected’? (ii) give a reason for your answer in (b) (i) above.
ANSWERS
​(a) (i) Diffusion;
(ii) Sea water contains a higher concentration of sodium ions than the cell sap; (b) (i) Iodide ions; (ii) Sea water has a lower concentration of iodide ions than the cell. The plant requires energy to take up the iodide ions (by active transport);
K.C.S.E Biology Q & A - MODEL 2014PP1QN25
State two roles of luteinising hormone in human reproduction.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN24
The table provided shows the transportation of substances in the human body.
​Name the substances represented by
M N P
ANSWERS
​M - lungs;
N - Urea, ammonia. ; P - Digested food. water; mineral ions; K.C.S.E Biology Q & A - MODEL 2014PP1QN23
Below is an illustration of a cross section of a plant root showing the transportation of substances in the plant.
​(a) Name the substances transported along the paths labelled K and L.
K L (b) Give a reason for your answer in L above.
ANSWERS
​(a) K - Photosynthetic products/manufactured foods example vitamins/alicose/proteins/sucrose/maltose/fructose/lipids/nitrates;
L - Water and mineral salts; (b) The substances are moved into the star shaped xylem;
K.C.S.E Biology Q & A - MODEL 2014PP1QN22
Why are some bacteria able to resist the effect of antibiotics?
ANSWER
K.C.S.E Biology Q & A - MODEL 2014PP1QN22
Name two vestigial structures in human beings.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN21
Name the type of skeleton that makes tip each of the following animals:
(a) locust (b) bird.
ANSWERS
​(a) Exoskeleton;
(b) Endoskeleton; K.C.S.E Biology Q & A - MODEL 2014PP1QN20
State one function of each of the following cell organelles:
(a) golgi bodies (b) lysosomes.
ANSWERS
​(a) Packaging of substances/glycoproteins/ transportation of glycoproteins;
Secretion of synthesized proteins and carbohydrates; Formation of lysosomes/modification of carbohydrates to form glycoproteins; (1 mark) (b) Digestion of food/Breakdown large molecules; Destroy worn out organdies or cells/tissue;
K.C.S.E Biology Q & A - MODEL 2014PP1QN19
Why is a burning charcoal stove in a poorly ventilated room likely to cause death of the inhabitants?
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN18
Explain why four months after fertilisation, ovaries can be removed from a human female, without terminating pregnancy.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN18
Explain why mammalian testes are located to hang outside the body
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN17
Give a reason why the image is not formed when light is focused on the blind spot.
ANSWER
K.C.S.E Biology Q & A - MODEL 2014PP1QN16
The diagram below illustrates a nerve cell.
​(a) Name the type of nerve cell illustrated.
(b) Give a reason for your answer in (a) above (c) identify the part labelled J (d) State one function of each of the parts labelled G and H. (i) G (ii) H
ANSWERS
(a) Sensory neurone;
(b) Cell body is located off the axon/tied outside the CNS; (c) Schwann cell; (d) (i) Receipt/transmits impulses to neighbouring neurons in the CNS from sense organs; (ii) Insulates the axon/accept dendron for axon;
K.C.S.E Biology Q & A - MODEL 2014PP1QN15
Distinguish between a tendon and a ligament.
ANSWERS
K.C.S.E Biology Q & A - MODEL 2014PP1QN15
Which type of mammalian muscles is voluntary’?
ANSWER
K.C.S.E Biology Q & A - MODEL 2014PP1QN14
State three structural differences between DNA and RNAK.C.S.E Biology Q & A - MODEL 2014PP1QN13
State one function of each of the following parts of a mammalian eye:
(a) eye lashes (b) lachrymal glands.
ANSWERS
​(a) Trap foreign particles entering the eye;
Produce fluid/tears; (b) Moistens the cornea; Wash foreign materials out of the eye; Antiseptic / kills harmful microorganisms; K.C.S.E Biology Q & A - MODEL 2014PP1QN12
The diagram below represents a model used to demonstrate breathing in mammals.
​(a) Name the mammalian structure represented by the parts labelled D and E.
(i) D . (ii) E (b) State the observation made when the string is pulled downwards. (c) Explain the observation in (b) above.
ANSWERS
​(a) (i) Rib-cage/chest cavity;
(ii) Diaphragm; (b) The balloons are inflated; (c) Pulling down the string increases the volume of D, hence decreasing the pressure inside: The low pressure causes external atmospheric air to rush in and inflate the balloons; K.C.S.E Biology Q & A - MODEL 2014PP1QN11
State three differences between tactic and tropic responses.
K.C.S.E Biology Q & A - MODEL 2014PP1QN10
What is meant by each of the following terms?
(i) Crenated cell. (ii) Flaccid cell.
ANSWERS
​(i) Crenated cell is a shrunk animal cell that has lost water by osmosis;
(ii) Flaccid cell is a flabby /shrunk plant cell that has lost waster by osmosis;
K.C.S.E Biology Q & A - MODEL 2014PP1QN10
Explain two roles of diffusion in human beings.
ANSWERS
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