OCR GCSE Biology A: Nervous system, coordinated responses and reflex arcs (J247) – 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 are aligned to the OCR GCSE (9-1) Gateway Science Biology A (J247) specification, Version 4.0 (August 2026), for first assessment in 2018. They cover B3.1a, B3.1b and B3.1c. None of these statements is Higher Tier only, so every question suits both tiers.

Links: study guide, revision notes, OCR GCSE Biology hub, printable checklist and the free 10-minute diagnostics. For the g value, use 9.8 m/s² where needed.

Questions

1. (a) Put these parts of a reflex arc in the order the impulse passes through them: effector, motor neurone, receptor, relay neurone, sensory neurone. [2] (b) State what the central nervous system is made of. [1]

2. Describe two structural features of a motor neurone and explain how each helps it do its job. [4]

3. Explain how a signal passes from one neurone to the next at a synapse, and why it can only pass in one direction. [4]

4. In a ruler drop test, a ruler falls 27 cm before it is caught. Calculate the reaction time using t = √(2d/g). Give your answer to 2 significant figures. [3]

5. A student measured her reaction time five times with no distraction, and five times while reading a text message. The results are in seconds.

Condition	1	2	3	4	5
No distraction	0.19	0.21	0.20	0.22	0.18
Reading a message	0.27	0.30	0.28	0.26	0.29

(a) Calculate the mean reaction time for each condition. [2] (b) Calculate the percentage increase in mean reaction time caused by reading the message. [2] (c) State one variable the student should keep the same in both conditions. [1]

6. A driver sees a traffic light turn red, hears a horn from the left and brakes. Explain how the nervous system produces a coordinated response in this situation. [4]

7. A person touches a hot kettle and moves their hand away before they feel any pain. Explain how the structure of the reflex arc makes this possible. [6]

8. Use the following simplified data. Impulses travel along neurones at 75 m/s. Each synapse adds a delay of 0.8 ms (0.0008 s). A reflex path is 0.9 m long and has 2 synapses. A voluntary path for the same stimulus is 1.5 m long and has 9 synapses. (a) Calculate the total time for the reflex response. [3] (b) Calculate the total time for the voluntary response, and state how many times longer it is than the reflex. [2]

9. A person did five ruler drop tests in a row. Their reaction times were 0.25 s, 0.22 s, 0.20 s, 0.19 s and 0.19 s. (a) Describe the pattern in the results. [2] (b) Calculate the percentage decrease from test 1 to test 5. [2] (c) Suggest an explanation for the pattern. [1]

10. Two patients each have damage to one part of a pathway in the leg. Patient A feels a pin pressed on the foot but cannot move the foot away, even when asked. Patient B cannot feel the pin and there is no movement of the foot, but can move the foot normally when asked to. (a) Identify the part of the pathway that is most likely damaged in Patient A, and explain your answer. [3] (b) Identify the part most likely damaged in Patient B, and explain your answer. [3]

11. Plan an investigation to find out whether the reaction time of the dominant hand differs from that of the other hand, using the ruler drop method. Include how you would make the results reliable and how you would deal with an anomaly. [8]

12. Name the structure that matches each description. (a) A short neurone found only inside the CNS. [1] (b) A muscle or gland that carries out a response. [1] (c) The narrow gap where two neurones meet. [1]

Answers

1. (a) Receptor, sensory neurone, relay neurone, motor neurone, effector. One mark for receptor first and effector last [1]; one mark for the middle three in the right order [1]. (b) The brain and the spinal cord [1]. [3] Examiner insight: In an order question, check the whole sequence: sensory comes before relay, and relay before motor.

2. Any two features, each with its function. Long axon [1], so it can carry impulses over long distances, for example from the spinal cord to a muscle in the leg [1]. Myelin sheath (fatty insulating layer) [1], which insulates the axon and makes the impulse travel faster [1]. Other creditworthy pairs: cell body with dendrites that receives impulses from other neurones; branched endings that pass the signal on to the effector. [4] Examiner insight: A feature on its own earns nothing for the function. Write “because” or “so that” and say what the feature allows.

3. The impulse reaches the end of the first neurone, which releases a transmitter chemical into the gap [1]. The chemical diffuses across the gap [1]. It binds to receptor molecules on the second neurone [1], which starts a new impulse there. The receptors are only on the second neurone and the chemical is only released by the first, so the signal passes in one direction only [1]. [4] Examiner insight: Saying the electrical impulse “jumps” the gap is a common wrong idea. Name a chemical and say it crosses by diffusion.

4. d = 27 cm = 0.27 m [1]. t = √(2 × 0.27 / 9.8) = √0.05510 [1]. t = 0.2347, so 0.23 s to 2 significant figures [1]. [3] Examiner insight: Converting centimetres to metres is the step most often missed. Show it, so that your working makes clear what you did.

5. (a) No distraction: total 1.00, mean = 1.00 / 5 = 0.20 s [1]. Reading a message: total 1.40, mean = 1.40 / 5 = 0.28 s [1]. (b) Increase = 0.28 - 0.20 = 0.08 s [1]. Percentage = 0.08 / 0.20 × 100 = 40% [1]. (c) Any one: same hand, same ruler, same person dropping it, same starting position, same time of day [1]. [5] Examiner insight: Percentage change is divided by the original value, here the no-distraction mean, not the new one.

6. Light receptors in the eyes detect the red light and sound receptors in the ear detect the horn [1]. These are different sensory receptors that each detect a different stimulus [1]. Sensory neurones carry the impulses to the CNS, which combines the information from both [1]. Motor neurones carry impulses to the muscles of the leg (effectors), which press the brake [1]. [4] Examiner insight: Use the term “different receptors” and say that the CNS combines the information. A list of neurones with no mention of coordination will not cover the whole answer.

7. Heat receptors in the skin detect the high temperature [1]. A sensory neurone carries impulses to the spinal cord [1]. A relay neurone in the CNS connects it directly to a motor neurone [1], so the response does not wait for a conscious decision [1]. There are few neurones and only two synapses, so the pathway is short and the delay is small [1]. The motor neurone carries impulses to a muscle in the arm (effector), which contracts and moves the hand away [1]. The pain is felt a moment later because information also passes on to the brain, which is slower to respond. [6] Examiner insight: For an “explain how the structure” question, link each feature (few neurones, relay neurone, few synapses) to the speed or the automatic nature of the response, not just list the arc.

8. (a) Travel time = 0.9 / 75 = 0.012 s [1]. Synapse delay = 2 × 0.0008 = 0.0016 s [1]. Total = 0.0136 s, or 13.6 ms [1]. (b) Travel time = 1.5 / 75 = 0.020 s and synapse delay = 9 × 0.0008 = 0.0072 s, total = 0.0272 s (27.2 ms) [1]. Ratio = 0.0272 / 0.0136 = 2.0 times longer [1]. [5] Examiner insight: Show the travel time and synapse delay separately and add them. Real voluntary responses are slower still, because the model ignores processing in the brain.

9. (a) Reaction time decreases with each test [1] and levels off at 0.19 s for the last two tests [1]. (b) Decrease = 0.25 - 0.19 = 0.06 s [1]. 0.06 / 0.25 × 100 = 24% [1]. (c) The person improved with practice, learning to watch the ruler and respond sooner [1]. [5] Examiner insight: A description should quote the data (0.25 s falling to 0.19 s). Explaining the pattern is a separate mark, so keep description and explanation apart.

10. (a) The motor neurone (or the muscle, the effector) [1]. The pin was felt, so the receptor, the sensory neurone and the CNS are working [1]. Impulses cannot reach the muscle or the muscle cannot contract, so there is no movement [1]. (b) The sensory neurone (or the receptor) [1]. No impulses reach the CNS from the foot, so there is no sensation and no reflex [1]. The motor neurone and muscle work, because the foot moves when the person decides to move it [1]. [6] Examiner insight: Give the part and the evidence for it. Ruling out the other parts with the information in the stem is what earns the explanation marks.

11. Up to eight marks from the following points. Independent variable: the hand used (dominant or other) [1]. Dependent variable: the distance the ruler falls, converted to reaction time with t = √(2d/g), or reaction time [1]. Same person catches throughout. Same ruler, same starting position of thumb and finger, same person dropping it [1]. Drop the ruler without warning at random intervals [1]. Repeat several times for each hand, for example five [1]. Calculate a mean for each hand [1]. Do a few practice drops first (or alternate the hands) so that practice does not favour one hand [1]. Identify any result far from the others as an anomaly and repeat it, or leave it out of the mean and say so [1]. Compare the means, and say that one person is not enough for a general conclusion. [8] Examiner insight: A plan scores for specific control variables and for how results are used, such as the mean and the treatment of an anomaly. “Make it a fair test” without saying what is kept the same does not score.

12. (a) Relay neurone [1]. (b) Effector [1]. (c) Synapse [1]. [3] Examiner insight: Spell the key terms correctly and use the whole term. “Neurone” and “nerve” are not interchangeable.

Where marks are usually lost

• Writing nerve for neurone, or sensory for motor, when naming the direction of the impulse.
• Leaving the CNS out of the pathway, or the relay neurone out of a reflex arc.
• Saying the impulse “jumps” the synapse instead of naming a chemical that diffuses across the gap.
• Claiming a reflex does not involve the brain at all, instead of saying there is no conscious decision.
• Not converting centimetres to metres before using t = √(2d/g).
• Dividing a percentage change by the new value instead of the original.
• Listing parts of a neurone without linking each to its function.

Next steps

• Go back to the revision notes for any answer you lost marks on.
• Reread the study guide for the structure of the reflex arc.
• Tick off what you can do on the printable checklist and see the course hub.
• Try all the free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

OCR, GCSE (9-1) Gateway Science Biology A (J247) specification, Version 4.0 (August 2026), first assessment 2018. Statements B3.1a to B3.1c.