This page has the questions that were on KNEC’s 2021 KCSE Biology Paper 2 exam.
Use it to revise for your biology exam. Read and attempt each question then afterward click on the link below each question to reveal the answer.
Section A
Answer all questions in this section in the spaces provided.
1. The photograph below shows an organism from a certain Class of organisms.
(a)
(i) Name the Class to which the organism belongs.
(1 mark)
(ii) Using observable features from the photograph, state two reasons for your answer in 1 (a) (i),
(2 marks)
iii. State two ways in which the organism is important to the environment.
(2 marks)
(b)
(i) Name the Kingdom to which bacteria belong.
(1 mark)
(ii) Name two bacterial diseases in human beings. (2 marks)
(a)
(i) Diplopoda
(ii)
- Two pairs of walking legs per segment;
- Many segments / more than 9 segments.
- A pair of short antennae.
- cylindrical
(iii)
- Decomposes the organic matter/enriches soil fertility
- Aerates the soil through its movements/burrowing
(b)
(i) Monera
(ii) Cholera, Typhoid, Tetanus, Syphilis, Tuberculosis, (first two)
2.
(a) State two adaptations of the frog’s skin to gascous exchange.
(2 marks)
(b) Explain how the human nasal cavity is adapted to gaseous exchange.
(3 marks)
(c) Explain why the amoeba does not require an elaborate gaseous exchange system.
(2 marks)
(d) Name the respiratory disease caused by Bordetella partusis
(1 mark)
(a)
- Moist to dissolve respiratory gas for faster gaseous exchange
- Thin Lined with a one-cell-thick epithelium for faster diffusion of respiratory gases
- Highly vascularized for faster/efficient transportation of respiratory gases
(Any two)
(b)
- Lined with hair; to trap dust particles/foreign materials/purify (the incoming) air,
- Has mucus; to moisten/warm the incoming air
(c) Unicellular. Has a large surface area to volume ratio; diffusion (across its cell membrane) is adequate;
3. The diagram below shows a section through the mammalian skin.
(a)
(i) Name the substance produced by the part labelled G.
(1 mark)
(ii) State two functions of the substance named in 3(a)(i).
(2 marks)
(b) Name the part labelled E.
(1 mark)
(c) Explain the function of the part labelled F to the mammal.
(2 marks)
(i) Name one part of the human body where the cornified layer is thickest.
(1 mark)
(ii) Give a reason for your answer in 3(c)(i).
(1 mark)
(a) Sebum;
(b) keeps the skin moist/supple,
acts as an antiseptic; – accept kills bacteria makes the skin/hair water repellant / water proof
(c) Sweat pore;
Thermoregulation; lies flat or erects (on the skin surface) when hot/cold to conserve heat or emit excess heat; e.
(d)
(i) Sole or the feet palm of hands;
(ii) Thickest because they encounter high friction/hard-walking (soles of feet) and manual work (palms of hands);
4.
(a) Two dogs with black fur mated and produced an offspring with both black and brown fur.
Given letter N represents the gene for black fur, determine the phenotypic ratio of the offspring.
(5 marks)
(b) The photographs below show a hairy pinna in a human ear.
5.
(a) State the role of sunlight in the formation of strong bones.
(1 mark)
(b) The photograph below shows the dorsal view of a part of the mammalian vertebral column.
(i) Name the part of the vertebral column shown.
(1 mark)
(ii) Name the part labelled H.
(1 mark)
(iii) State three ways in which the vertebra shown is adapted to its functions.
(3 marks)
(c) Explain the significance of movement in plants.
Section B
Answer question 6 (compulsory) and either question 7 or 8.
6. The table below shows the varying concentration of two hormones, progesterone and luteinising hormone, determined at seven-day intervals during the human menstrual cycle.
| Time in days | 1 | 7 | 14 | 21 | 28 |
| Concentration of progesterone (mg/cm3 of blood) | 2 | 2 | 24 | 100 | 20 |
| Concentration of luteinizing hormone (mg/cm3 of blood) | 46 | 40 | 100 | 84 | 40 |
(a) On the same axis, draw graphs of concentration of hormones against time.
(8 marks)
(b)
(i) Name the physiological process taking place when the concentration of luteinizing hormone is highest.
(1 mark)
(ii) State the significance of the process named in 6 (b) (i).
(1 mark)
(c)
(i) Determine the concentration of progesterone hormone at which the endometrium is thickest.
(1 mark)
(ii) Explain your answer in 6(c)(i).
(1 mark)
(d) State two roles of progesterone hormone in humans.
(2 marks)
(e) Name two sites where progesterone hormone is produced in the human body.
(2 marks)
(f) Name another hormone, apart from the luteinizing hormone, that inhibits the secretion of progesterone hormone.
(1 mark)
(g)
(i) Predict the concentration of progesterone hormone seen days after the study period if fertilisation did not take place.
(1 mark)
(ii) Give a reason for your answer in 6(9)(i). (1 mark)
(h) Name the part of the human body where the luteinizing hormone is produced.
(1 mark)