Cambridge O Level Biology 5090: Coordination and control (5090) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover Topic 14, Coordination and control, of the Cambridge O Level Biology 5090 syllabus for examination in 2026, 2027 and 2028 (version 4): every learning outcome in sections 14.1 to 14.6. The syllabus is not tiered, so every question applies to every candidate.

Revise first with the study guide and the revision notes. A calculator is useful for questions 2, 5, 9 and 11. All data are given values for the calculation, not reference figures to learn.

Questions

1. Describe the mammalian nervous system in terms of the central nervous system and the peripheral nervous system. [2]

2. A diagram shows three neurones in a reflex arc.

• Neurone A has its cell body inside the spinal cord and one long fibre that ends in a leg muscle.
• Neurone B is short and branched, and lies entirely inside the spinal cord.
• Neurone C has its cell body on a short side branch outside the spinal cord, with one end in the skin.

(a) Identify neurones A, B and C. [3] (b) State what travels along a neurone. [1] (c) An impulse travels the 0.90 m length of neurone A in 0.015 s. Calculate the speed of the impulse in m/s. [2]

3. This question is about synapses.

(a) Name the structures in which neurotransmitter molecules are stored. [1] (b) Describe the events at a synapse after an impulse arrives. [3] (c) Explain why an impulse can cross a synapse in one direction only. [2]

4. A boy steps on a drawing pin and lifts his foot before he feels pain.

(a) Describe what is meant by a reflex action. [2] (b) Identify the receptor and the effector in this response. [2] (c) Suggest one advantage of this response. [1]

5. A student measured her reaction time by catching a dropped ruler, five times with each hand. Catching the ruler is a voluntary action, not a reflex.

Trial	1	2	3	4	5
Right hand / s	0.22	0.19	0.21	0.20	0.23
Left hand / s	0.25	0.27	0.24	0.26	0.28

(a) Calculate the mean reaction time for each hand. [2] (b) Calculate the difference between the two means. [1] (c) Suggest why she repeated each measurement five times. [1] (d) State one variable she should keep the same. [1]

6. This question is about sense organs.

(a) Describe a sense organ. [1] (b) Name the part of the eye that: (i) contains the greatest density of light receptors [1] (ii) refracts light at the front of the eye [1] (iii) carries impulses to the brain. [1] (c) Explain why light falling on the blind spot is not detected. [1]

7. A girl in a dark cinema looks down from the screen to read a ticket held close to her face.

(a) Explain how her eye focuses on the ticket. [4] (b) Explain how her iris keeps her pupils wide in the dark. [3]

8. This question is about hormones.

(a) Describe a hormone. [3] (b) State the hormones produced by: (i) the pituitary gland [1] (ii) the testes [1] (iii) the ovaries. [1]

9. A man’s heart rate rose from 68 to 102 beats per minute when a car swerved towards him.

(a) Name the hormone responsible and the gland that produces it. [2] (b) Calculate the percentage increase in heart rate. [2] (c) Explain how this hormone helps him to run out of the way. [3] (d) Compare nervous and hormonal control. [2]

10. A cyclist’s core body temperature was measured during exercise in a warm room.

Time / min	0	5	10	15	20	25
Core temperature / °C	37.0	37.4	37.8	38.1	38.2	38.2

(a) Describe homeostasis. [1] (b) Calculate the total rise in core temperature. [1] (c) Describe the roles of the hypothalamus and the skin temperature receptors in temperature control. [2] (d) Explain two processes that stop the temperature rising further after 20 minutes. [4]

11. Person X and person Y each drank a glucose solution at 0 minutes. Person Y has Type 1 diabetes.

Time / min	0	30	60	90	120
X: blood glucose / mg per 100 cm³	90	140	120	95	90
Y: blood glucose / mg per 100 cm³	160	260	290	280	270

(a) Calculate the percentage increase in blood glucose for X between 0 and 30 minutes. Give your answer to the nearest whole number. [2] (b) Explain the change in X’s blood glucose between 30 and 120 minutes, using the idea of negative feedback. [4] (c) State one sign of Type 1 diabetes shown in the table and one other sign. [2] (d) State the treatment for Type 1 diabetes. [1] (e) Explain the need to control blood glucose concentration. [2]

12. Arctic foxes live where air temperatures can be far below 0 °C.

(a) Name the structure in the skin that: (i) secretes sweat [1] (ii) makes a hair stand up [1] (iii) forms an insulating layer beneath the skin. [1] (b) Suggest and explain two ways an arctic fox reduces heat loss through its skin in very cold air. [4]

Answers

1. The CNS consists of the brain and the spinal cord [1]. The PNS consists of the nerves outside the brain and spinal cord [1]. [2] Examiner insight: “The PNS is all the nerves” is not enough; the answer needs “outside the brain and spinal cord”.

2. (a) A: motor neurone [1]; B: relay neurone [1]; C: sensory neurone [1]. (b) Electrical impulses [1]. (c) speed = 0.90 ÷ 0.015 [1] = 60 m/s [1] [6] Examiner insight: Write the division out and give the unit; a bare number without m/s is incomplete.

3. (a) Vesicles [1]. (b) The impulse causes neurotransmitter to be released from vesicles into the synaptic gap [1]. The neurotransmitter diffuses across the gap [1] and binds with receptor proteins, so an impulse is stimulated in the next neurone [1]. (c) Vesicles containing neurotransmitter are only in the first neurone [1]; receptor proteins are only on the next neurone [1]. [6] Examiner insight: Name the process as “diffuses”; words like “travels” or “flows” leave the movement unexplained.

4. (a) A response that is rapid [1] and automatic, without conscious thought [1]. (b) Receptor: pain or touch receptors in the skin of the foot [1]. Effector: a muscle in the leg [1]. (c) Reduces damage to the foot, because the foot is removed quickly [1]. [5] Examiner insight: “The foot” is not an effector; name a muscle or gland, because effectors are the structures that respond.

5. (a) Right: 1.05 ÷ 5 = 0.21 s [1]; left: 1.30 ÷ 5 = 0.26 s [1]. (b) 0.26 − 0.21 = 0.05 s [1]. (c) To identify anomalous results and calculate a reliable mean [1]. (d) Any one [1]: the same ruler; the same starting position of the hand; the same person dropping the ruler. [5] Examiner insight: Give each mean with its unit and to the same decimal places as the data.

6. (a) A group of receptor cells responding to a specific stimulus [1]. (b) (i) Fovea [1] (ii) Cornea [1] (iii) Optic nerve [1]. (c) The blind spot has no light receptors [1]. [5] Examiner insight: In (b)(ii), “lens” does not fit: the question asks about the front of the eye, which is the cornea.

7. (a) The ciliary muscles contract [1]. The suspensory ligaments slacken, so tension in them decreases [1]. The lens becomes fatter, more convex [1], so light is refracted more and focused on the retina [1]. (b) The radial muscles of the iris contract [1] and the circular muscles relax [1]; the muscles act antagonistically, so the pupil dilates and more light enters [1]. [7] Examiner insight: In (a), each step of the chain (muscle, ligament tension, lens shape, refraction) is a separate point, so skipping the ligaments costs marks.

8. (a) A chemical substance [1], produced by a gland and carried by the blood [1], which alters the activity of one or more specific target organs [1]. (b) (i) FSH and LH [1] (ii) Testosterone [1] (iii) Oestrogen and progesterone [1]. [6] Examiner insight: For (b)(i) and (iii), one hormone alone is incomplete; give both names, spelt clearly.

9. (a) Adrenaline [1], from the adrenal glands [1]. (b) (102 − 68) ÷ 68 × 100 [1] = 50 % [1] (c) Adrenaline increases the blood glucose concentration [1] and the heart rate, so glucose and oxygen reach the leg muscles faster [1]. More respiration releases more energy for muscle contraction [1]. (d) Nervous control acts faster than hormonal control [1]; the effect of hormonal control lasts longer [1]. [9] Examiner insight: In (d), use comparative words for both points; “nervous is fast” alone does not make a comparison.

10. (a) The maintenance of a constant internal environment [1]. (b) 38.2 − 37.0 = 1.2 °C [1]. (c) Temperature receptors in the skin detect changes in temperature and send impulses to the brain [1]. The hypothalamus monitors blood temperature and coordinates the responses [1]. (d) Sweating: sweat glands release more sweat, and evaporation of the water transfers heat away from the body [1] [1]. Vasodilation: arterioles supplying the skin surface capillaries widen [1], so more blood flows near the surface and more heat is lost by radiation [1]. [8] Examiner insight: For vasodilation, name the arterioles; writing that capillaries move nearer the skin gives a wrong mechanism.

11. (a) (140 − 90) ÷ 90 × 100 [1] = 55.6 % = 56 % [1] (b) Blood glucose rose above the set point [1]. The pancreas releases more insulin [1]. Insulin causes the liver to convert glucose to glycogen [1], so blood glucose falls back to the set point, reaching 90 again at 120 minutes [1]. (c) Shown: increased blood glucose concentration (Y is higher at every time) [1]. Other: glucose in the urine [1]. (d) Administration of insulin [1]. (e) Cells need a steady supply of glucose for respiration [1]; a high concentration lowers the water potential of the blood, so water leaves cells by osmosis [1]. [11] Examiner insight: Quote figures from the table in (b) and (c) when data are given.

12. (a) (i) Sweat gland [1] (ii) Hair erector muscle [1] (iii) Fatty tissue [1]. (b) Hair erector muscles contract, so the fur stands up and traps a thicker layer of air [1], which insulates and reduces heat loss [1]. Vasoconstriction: arterioles supplying the skin surface capillaries narrow [1], so less blood flows near the surface and less heat is lost [1]. [7] Examiner insight: Shivering makes heat; it does not reduce heat loss, so it does not answer (b).

Where marks are usually lost

• Leaving the relay neurone out of a reflex arc.
• Writing that neurotransmitter “travels” across the gap instead of diffusing.
• Describing the eye’s response to dim light with the circular and radial muscles swapped.
• For near vision, saying the suspensory ligaments tighten.
• Naming “glucagon” when the answer needs “glycogen”, or the other way round.
• Stating that skin capillaries move towards or away from the surface.
• Writing that the sweat itself cools the skin, without saying water evaporates.
• Comparing nervous and hormonal control without comparative words.

Next steps

• Recap with the revision notes.
• Reread hard sections in the study guide.
• Link this topic to Excretion and Enzymes.
• See every topic on the course hub and tick off outcomes on the printable checklist.
• Try the free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

Cambridge O Level Biology 5090 syllabus for examination in 2026, 2027 and 2028 (version 4), Topic 14: Coordination and control (14.1 Mammalian nervous system; 14.2 Mammalian sense organs; 14.3 Mammalian hormones; 14.4 Homeostasis; 14.5 Temperature control; 14.6 Blood glucose control), published by Cambridge Assessment International Education.