KCSE Past Papers 2018 Biology Paper 2 (231/2)
The Kenya National Examinations Council
Kenya Certificate of Secondary Education 231/2 - Biology - Paper 2 Nov. 2018 - 2 hours
Answer all the questions in the spaces provided.
SECTION A (40 marks)
Answer all the questions in this section in the spaces provided.
1. The diagram below illustrates a section of the mammalian kidney.
(a) Name the structures labelled E and F. Region H (1 marks)
E ...........(1 marks)
F...........(1 marks)
(b) Explain the processes that take place in the regions labelled G and H. Region G(3 marks)
Region H(3 marks)
2. Below is a graphical representation of students’ height in a classroom.
(b) (i) State the type of variation represented by the curve.
(ii) State two meiotic processes that lead to variation among organisms. (2 marks)
(iii) Explain the role of variation in organisms.(2 marks)
(c) EKplain the need for genetic counselling in present day health facilities. (2 marks)
3.The amount of blood flowing through certain parts in the mammalian body at different activity levels was measured and results tabulated as shown in the table below.
(a) Account for:
(i) the high blood-flow through the cardiac and skeletal muscles during strenuous exercises. (4 marks)
(ii) the results obtained for the alimentary canal at rest. (2 marks)
(b) Name two waste materials excreted by both the skin and the kidneys. (2 marks)
4.The diagram below illustrates the arrangement of bones in a human arm.
(i) G
the type of joints formed at points H and M.
H (1 mark)
M (1 mark)
(ii) bone G (I mark)
(b) Name bone J and state how it is adapted to its functions. Name: (1 mark)
Adaptation (3 marks)
(c) State one functional difference between a tendon and a ligament. ( I mark)
5. The photograph below represents a plant in a certain Division.
(a) (i) Name the Division to which the plant belongs.(1 marks)
(ii) With reference to the photograph, state three observable features of the Division named in a(i) above. (3 marks)
(b) Name the parts labelled N and P.
N............(1 marks)
P............(1 marks)
(c) Explain how the part labelled Q is adapted to its functions.(2 marks)
SECTION B (40 marks)
Answer question 6 (compulsory) and either questfOn 7 or 8 in the spaces provided after question 8.
6. The effect of auxin concentration on growth response of two parts of a plant, X and Y was investigated over a period of time. The results were tabulated as shown in the table below.
Reason.............(1 marks)
Y.......................(1 marks)
Reason.....................(1 marks)
(c) From the graph identify: (i) the point at which the percentage stimulation was the same for both X and Y. (1 marks)
(ii) the optimum concentration of auxins required for part Y (1 marks)
(d) State three ways in which the effects of auxins on plants is applied in flower farming.(3 marks)
(e) Distinguish between simple and conditioned reflex action (3 marks)
7. (a) Describe the mode of reproduction in a named fungus.(5 marks)
(b) Describe the role of hormones in the human menstrual cycle. (15 marks)
8. Describe what happens to a meal rich in proteins along the alimentary canal from ingestion to egestion. (20 marks)
BIOLOGY Questions and answers
Biology Paper 2 (231/2)
1. The diagram below illustrates a section of the mammalian kidney.
(a) Name the structures labelled E and F. Region H (1 marks)
E Glomerulus;
F Artery/branch of renal artery
(b) Explain the processes that take place in the regions labelled G and H. Region G(3 marks)
At the (glomerulus), the afferent arteriole which brings blood to the glomerulus is wider than the efferent arteriole; this creates high pressure; leading to ultrafiltration;
At the proximal convoluted tubule /dista1 convoluted tubule, substances required by the body/amino acid substances required by the body (amino acids/glucose/vitamins/ some water; are selectively re-absorbed (into the blood stream); hence selective reabsorption
Region H(3 marks)
At the descending arm or/limb of the Loop of Henle, water is selectively reabsorbed; At the ascending arm/limb of the Loop of Henle, sodium ions/salts are actively/selectively reabsorbed; At the collecting duct, water is (selectively) reabsorbed:
2. Below is a graphical representation of students’ height in a classroom.
(a) Name the type of curve illustrated.
Normal distribution curve
(b) (i) State the type of variation represented by the curve.
Continuous (variation);
(ii) State two meiotic processes that lead to variation among organisms. (2 marks)
Organisms/individuals with advantageous traits/variations are favoured/selected by nature; and survive to reproduce/pass on/propagate the advantageous/favourable traits to their off-spring
(c) Explain the need for genetic counselling in present day health facilities. (2 marks)
(a) Account for:(i) the high blood-flow through the cardiac and skeletal muscles during strenuous exercises. (4 marks)
During strenuous exercises, the heart beat/pulse rate is increased (more contraction/relaxation of cardiac muscles);
while the rate of contraction and Telaxation of skeletal muscles is increased;
hence more blood flows to supply more oxygen/nutrients; and for removal of metabolic waste products (carbon (IV) oxide/urea);
(ii) the results obtained for the alimentary canal at rest. (2 marks)
At rest, more blood flows through the alimentary canal/gut/gastral intestinal tract (since digestion is at optimum at rest); to transport digested/absorbed food materials/eliminate metabolic wastes;
(b) Name two waste materials excreted by both the skin and the kidneys. (2 marks)
(a) Name:(i) The type of joints formed at points H and M.H Ball and socket (joint); (1 mark)
M Gliding/planar/p1ane (joint) (1 mark)
(ii) bone G (I mark)
ii. Clavicle
(b) Name bone J and state how it is adapted to its functions. Name: (1 mark)
- Scapula;
Adaptation (3 marks)
Ligaments hold the bones together (at a joint) while tendons attach muscles to bones;
5. The photograph below represents a plant in a certain Division.
(a) (i) Name the Division to which the plant belongs.(1 marks)
N = Capsule(1 marks)
P = Seta(1 marks)
(c) Explain how the part labelled Q is adapted to its functions.(2 marks)
Answer question 6 (compulsory) and either questfOn 7 or 8 in the spaces provided after question 8.
6. The effect of auxin concentration on growth response of two parts of a plant, X and Y was investigated over a period of time. The results were tabulated as shown in the table below.
(a) On the same axis, draw line graphs of the effect on growth of the two parts, X and Y (percentage inhibition or stimulation) against the concentration. (8 marks)
(b) With reasons, name the two parts of the plant, X and Y. X
Reason
Low auxins concentration has little effect on the growth of shoots/shoots are stimulated to grow with high auxin concentration (upto given optimum)
(c) From the graph identify:
(i) the point at which the percentage stimulation was the same for both X and Y. (1 marks)
33% ± 2
(ii) the optimum concentration of auxins required for part Y (1 marks)
1.0 parts per million
(d) State three ways in which the effects of auxins on plants is applied in flower farming.(3 marks)
(b) Describe the role of hormones in the human menstrual cycle. (15 marks)
8. Describe what happens to a meal rich in proteins along the alimentary canal from ingestion to egestion. (20 marks)
Got it right
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