Nervous Coordination: AQA A Level Biology Exam Questions by Topic

AQANervous CoordinationExam Questions
Written by Tom Whitburn

Nervous coordination (AQA 3.6.2) is A-level only, so it's Year 13 content. You need the structure of a myelinated motor neurone, how a resting potential is set up and kept, how an action potential is generated and passed along myelinated and non-myelinated axons, and why the refractory period matters. Then comes synaptic transmission: the cholinergic synapse and the neuromuscular junction, unidirectionality, summation, inhibitory synapses and using information to explain how drugs act.

The examiners' reports find the same gaps every year. Students say sodium ion channels open but never say sodium ions enter, have vesicles crossing the synaptic cleft, and put receptors on 'the muscle' instead of the postsynaptic membrane or sarcolemma. On the resting potential they send ions the wrong way or say the pump works by diffusion, and on myelination they call myelin a thermal insulator or have impulses 'jumping'.

Start with the neurone and the resting potential, work through action potentials and synapses, then try the drug and disease questions and the speed calculation. Write your answer on paper before you open each mark scheme. If you'd like help with this topic, my AQA masterclasses run online on Tuesdays at 5.15pm for Year 12 and on Wednesdays or Thursdays at 6.30pm for Year 13.

What you need from GCSE and Year 12

Each question on this page assumes you're secure on these GCSE and Year 12 ideas. If any of them feels shaky, revise it before you start.

  • GCSE: neurones carry electrical impulses from receptors to the central nervous system and on to effectors, and a chemical diffuses across the synapse between two neurones.
  • GCSE: a reflex arc runs from receptor to sensory neurone, relay neurone, motor neurone and effector.
  • Year 12 (AQA 3.2.3): ions cross membranes by facilitated diffusion through channel proteins, and by active transport through carrier proteins using ATP.
  • Year 12 (AQA 3.1.4.2): enzymes such as acetylcholinesterase have an active site and can be inhibited; receptors are not enzymes, so neurotransmitters bind to their binding sites.
  • Year 12 (AQA 3.1.8): ATP is made in respiration and hydrolysed to release energy for active transport.

Key terms

These words come up in the questions and mark schemes. Examiners expect you to use them exactly.

  • Resting potential: the potential difference of about −70 mV across the axon membrane when no impulse is passing: the inside is negative compared with the outside.
  • Sodium-potassium pump: a carrier protein that actively transports three sodium ions out of the axon for every two potassium ions in, using ATP.
  • Depolarisation: sodium ion channels open and sodium ions diffuse in, so the inside of the membrane becomes less negative and then positive.
  • All-or-nothing principle: an action potential is only produced if the threshold is reached, and every action potential is the same size; a bigger stimulus gives more action potentials, not bigger ones.
  • Refractory period: the time after an action potential when a new one can't be produced, so impulses are discrete, travel in one direction and are limited in frequency.
  • Saltatory conduction: in a myelinated axon, depolarisation happens only at the nodes of Ranvier, because the myelin sheath (made by Schwann cells) is an electrical insulator.
  • Cholinergic synapse: a synapse that uses acetylcholine: calcium ions enter the synaptic knob, vesicles fuse with the presynaptic membrane, and acetylcholine diffuses across the cleft to receptors on the postsynaptic membrane.
  • Acetylcholinesterase: the enzyme in the synaptic cleft that hydrolyses acetylcholine, so it stops binding to the receptors.
  • Neuromuscular junction: the synapse between a motor neurone and a muscle fibre; its postsynaptic membrane is the sarcolemma.
  • Temporal and spatial summation: temporal: several impulses in quick succession from one presynaptic neurone; spatial: impulses from several presynaptic neurones; either releases enough neurotransmitter to reach threshold.
  • Hyperpolarisation: the inside of the postsynaptic neurone becomes more negative than the resting potential (for example when chloride ions enter), so more sodium ions are needed to reach threshold.

What these questions cover (AQA 3.6.2)

The questions test these statements from the AQA AS and A-level Biology specification (7401/7402):

  • Myelinated motor neurone: The structure of a myelinated motor neurone.
  • Resting potential: The establishment of a resting potential in terms of differential membrane permeability, electrochemical gradients and the movement of sodium ions and potassium ions.
  • Action potentials: Changes in membrane permeability lead to depolarisation and the generation of an action potential. The all-or-nothing principle.
  • Passage along axons: The passage of an action potential along non-myelinated and myelinated axons, resulting in nerve impulses.
  • Refractory period: The nature and importance of the refractory period in producing discrete impulses and in limiting the frequency of impulse transmission.
  • Speed of conductance: Factors affecting the speed of conductance: myelination and saltatory conduction; axon diameter; temperature. (the questions here are on myelination and the reaction-time calculation; no written question on axon diameter or temperature was available for this page, so learn those two factors from your notes)
  • Synapse structure: The detailed structure of a synapse and of a neuromuscular junction.
  • Cholinergic synapse: The sequence of events involved in transmission across a cholinergic synapse in sufficient detail to explain:
  • Unidirectionality: unidirectionality
  • Summation: temporal and spatial summation (the question here is on temporal summation; no written question on spatial summation was available, so learn it from your notes (several presynaptic neurones release enough neurotransmitter together to reach threshold))
  • Inhibitory synapses: inhibition by inhibitory synapses.
  • Neuromuscular junction: A comparison of transmission across a cholinergic synapse and across a neuromuscular junction.
  • Drugs: Students should be able to use information provided to predict and explain the effects of specific drugs on a synapse. (you don't need to recall any drug; each question gives you what the drug does)

How to use this page

Write your answer on paper before you open the mark scheme. Allow about 1.3 minutes per mark: the 18 questions are worth 48 marks, so about 62 minutes in total. Then mark your answer strictly against the mark scheme and read the examiners' tip underneath it. If you'd rather print the questions, download the PDF pack.

Neurones and the resting potential (3.6.2.1)

Question 1

A level Paper 2 · June 2025 · Q06.1 · 2 marks · Easy

Name four labelled parts of a myelinated motor neurone.

Figure 2: drawing of a myelinated motor neurone with a cell body and dendrites on the left (A), a long axon (B) with myelin sheath segments separated by gaps (C), a Schwann cell with its nucleus (D) and branched axon terminals on the right. Question asks you to name parts A to D, 2 marks.
Show the mark scheme Mark scheme: 2 marks for four correct, 1 mark for two or three: A cell body (soma) or dendrites; B axon; C node of Ranvier; D Schwann cell. 'Myelin sheath' is not credited for D.

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From the examiners' report: About 45% got both marks. Write 'node of Ranvier', not just 'node', and D is a Schwann cell, not the myelin sheath or a nucleus.

Question 2

A level Paper 2 · November 2021 · Q02.1 · 3 marks · Medium

Explain how a resting potential is maintained across an axon membrane.

Question text: explain how a resting potential is maintained across the axon membrane in a neurone, 3 marks.
Show the mark scheme Mark scheme: higher concentration of potassium ions inside and sodium ions outside (or potassium ions diffuse out); membrane more permeable to potassium ions than sodium ions; sodium ions actively transported out and potassium ions in. Max 1 if ions are never mentioned; 3 Na⁺ out and 2 K⁺ in accepted, wrong numbers rejected.

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From the examiners' report: Only 13% got all three. The pump is active transport, three sodium ions out for two potassium ions in, and then say the membrane is more permeable to potassium ions, so they diffuse out.

Question 3

A level Paper 2 · November 2021 · Q02.3 · 3 marks · Hard

Explain why a respiratory inhibitor makes the resting potential change from −70 mV to 0 mV.

Question text: a scientist added a respiratory inhibitor to a neurone and the resting potential changed from −70 mV to 0 mV; explain why, 3 marks.
Show the mark scheme Mark scheme: no or less ATP produced; no or less active transport, or the sodium-potassium pump is inhibited; electrochemical gradient not maintained, or ions diffuse until there is the same concentration either side and no net movement.

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From the examiners' report: Only 8% got all three. Link the inhibitor to less ATP, not 'no energy produced', then to the sodium-potassium pump, and finish with the ions diffusing until there is no net movement.

Action potentials and conduction (3.6.2.1)

Question 4

A level Paper 3 · June 2023 · Q01.2 · 2 marks · Medium

Use a graph of membrane potential to describe the all-or-nothing principle.

Figure 1: membrane potential (mV) of a Pacinian corpuscle's sensory neurone against time (0 to 10 ms); high pressure gives a peak at about +35 mV at 2.5 ms, while low pressure at about 7 ms gives a small rise that stays below 0 mV, each followed by a dip below −70 mV. Question asks you to use Figure 1 to describe the all-or-nothing principle, 2 marks.
Show the mark scheme Mark scheme: an action potential is only produced when the threshold is reached; when high pressure was applied the threshold was reached (or high pressure generates an action potential; accept the converse for low pressure). Numbers for the threshold are ignored.

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From the examiners' report: A quarter got both marks; 41% got one because they described the principle without using Figure 1. Say high pressure reached threshold and low pressure didn't. You don't need a threshold value.

Question 5

A level Paper 3 · June 2023 · Q01.3 · 1 mark · Easy

Name the period when no new generator potential can be produced.

Question text: on Figure 1, from 0.6 ms to 4.0 ms, no new generator potential could be produced; what is this time period called? 1 mark.
Show the mark scheme Mark scheme: (the) refractory period. Absolute or relative is ignored; 'refraction period' is rejected.

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From the examiners' report: 66% got it. Read the times given: 0.6 to 4.0 ms covers the whole action potential, so it isn't hyperpolarisation, a rest period or lag time.

Question 6

A level Paper 2 · November 2021 · Q02.2 · 3 marks · Medium

Explain why impulses travel faster along a myelinated axon than a non-myelinated one.

Question text: explain why the speed of transmission of impulses is faster along a myelinated axon than along a non-myelinated axon, 3 marks.
Show the mark scheme Mark scheme: myelination provides electrical insulation; in myelinated axons saltatory conduction, or depolarisation at the nodes of Ranvier; in non-myelinated axons depolarisation occurs along the whole length. Thermal insulation is rejected; 'messages' or 'signals' lose a mark.

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From the examiners' report: Only 8% got all three. Myelin is an electrical insulator, not a thermal one. Use 'depolarisation' at the nodes rather than impulses 'jumping', and compare with depolarisation along the whole non-myelinated axon.

Question 7

A level Paper 2 · June 2019 · Q10.1 · 3 marks · Medium

Explain how damage to the myelin sheath can cause muscular paralysis.

Passage: Guillain–Barré syndrome is a rare disease in which the immune system damages the myelin sheath of neurones, causing numbness, muscular weakness and paralysis; it also covers heart rate and Huntington's disease. Question asks how myelin sheath damage can cause muscular paralysis (lines 2–4), 3 marks.
Show the mark scheme Mark scheme: refers to saltatory conduction (or depolarisation along the whole length, or impulses passing to other neurones); nerve impulses slowed or stopped; refers to the neuromuscular junction or sarcolemma. 'Messages' or 'signals' lose the first mark.

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From the examiners' report: 84% got a mark but only 11% got all three. After saltatory conduction and slower impulses, finish at the neuromuscular junction or sarcolemma. Use 'impulses' or 'action potentials', never messages or signals.

Synaptic transmission (3.6.2.2)

Question 8

A level Paper 2 · June 2024 · Q01.1 · 2 marks · Easy

Name four labelled parts of a neuromuscular junction.

Figure 1: drawing of a neuromuscular junction, a swollen synaptic knob containing several mitochondria (A) and many small round vesicles (C), with its outer membrane labelled B, sitting in a folded groove of the muscle fibre with a narrow gap between them (D). Question asks you to name parts A to D, 2 marks.
Show the mark scheme Mark scheme: 2 marks for four correct, 1 mark for two or three: A mitochondrion; B presynaptic membrane or neurone (accept synaptic knob or motor neurone); C synaptic vesicle; D synaptic gap or cleft.

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From the examiners' report: About 41% got both marks. C is a vesicle, not acetylcholine, calcium ions or a ribosome, and D is the synaptic cleft, not the 'synapse' or 'neuromuscular junction'.

Question 9

A level Paper 2 · November 2020 · Q05 · 5 marks · Medium

Describe the sequence of events in transmission across a cholinergic synapse.

Question text: describe the sequence of events involved in transmission across a cholinergic synapse, without details of the breakdown of acetylcholine, 5 marks.
Show the mark scheme Mark scheme, max 5: depolarisation of the presynaptic membrane; calcium channels open and calcium ions enter the synaptic knob; synaptic vesicles fuse with the presynaptic membrane and release acetylcholine; acetylcholine diffuses across the synaptic cleft; attaches to receptors on the postsynaptic membrane; sodium ions enter, leading to depolarisation.

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From the examiners' report: About 17% got all five and 21% scored zero. Calcium ions go in, not out; vesicles fuse and release acetylcholine, they don't cross the cleft; and say receptors, membrane and ions every time.

Question 10

A level Paper 2 · June 2022 · Q07.1 · 2 marks · Medium

Give two reasons why transmission across a cholinergic synapse is one way.

Question text: give two reasons why transmission across a cholinergic synapse is unidirectional, 2 marks.
Show the mark scheme Mark scheme: only the presynaptic neurone or membrane releases or has acetylcholine (neurotransmitter); only the postsynaptic membrane has receptors (no receptors on the presynaptic membrane).

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From the examiners' report: Only 66% got a mark and about 41% got both. Leave out the refractory period and calcium ions: only the presynaptic side releases acetylcholine and only the postsynaptic membrane has receptors.

Question 11

A level Paper 2 · June 2022 · Q07.2 · 2 marks · Medium

Name and explain the type of summation shown on a graph of postsynaptic membrane potential.

Figure 4: membrane potential in a postsynaptic neurone (−100 to +75 mV) against time after repeated stimulation from a single presynaptic neurone; two small rises from about −70 mV each fall back, then a third rise reaches threshold and an action potential peaks at about +55 mV. Question asks you to name and explain the type of summation, 2 marks.
Show the mark scheme Mark scheme: temporal; repeated impulses in a short time release enough neurotransmitter (acetylcholine), or let enough sodium ions enter, to reach threshold.

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From the examiners' report: Only about 20% got both marks. One presynaptic neurone means temporal, not spatial. Then explain why: enough neurotransmitter, or enough sodium ions entering, to reach threshold.

Question 12

A level Paper 2 · June 2024 · Q01.3 · 2 marks · Hard

Explain how hyperpolarisation at inhibitory synapses inhibits transmission.

Question text: inhibitory synapses cause hyperpolarisation in postsynaptic neurones; explain how this inhibits synaptic transmission, 2 marks.
Show the mark scheme Mark scheme: the inside of the postsynaptic neurone is more negative (potential below the resting potential); more sodium ions are required to enter for depolarisation or an action potential.

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From the examiners' report: About half got a mark but only about 18% got both. After 'more negative inside', say more sodium ions, not 'more sodium', must enter to reach threshold.

Question 13

A level Paper 2 · June 2024 · Q01.2 · 4 marks · Medium

Describe the events after acetylcholine is released at a neuromuscular junction.

Question text: following the release of acetylcholine into a neuromuscular junction a muscle contraction occurs; describe the sequence of events after the release of acetylcholine that leads to stimulation of contraction, not including events after calcium ions are released in the myofibril, 4 marks.
Show the mark scheme Mark scheme: acetylcholine diffuses across the synaptic cleft; attaches to receptors on the sarcolemma; sodium ions enter, leading to depolarisation; calcium ions released by the sarcoplasmic reticulum. Wrong sequence loses a mark; 'sodium ion channels opening' alone is not enough.

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From the examiners' report: Only about 7% got all four. Start after the release, put the receptors on the sarcolemma, not 'the muscle', say sodium ions enter, and finish with calcium ions released from the sarcoplasmic reticulum.

Drugs, disease and synapses (3.6.2.2)

Question 14

A level Paper 2 · June 2018 · Q07.2 · 2 marks · Easy

Explain how morphine, which resembles endorphins, gives pain relief.

Question text: dopamine release can be stimulated by endorphins, which attach to opioid receptors on presynaptic neurones that release dopamine; morphine has a similar structure to endorphins and can provide pain relief. Question asks how, 2 marks.
Show the mark scheme Mark scheme: morphine attaches to opioid receptors; more dopamine is released. 'Active site' and 'receptors release dopamine' are rejected.

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From the examiners' report: 88% got a mark and 63% got the receptor mark. Say opioid receptors, and don't give the receptor an active site.

Question 15

A level Paper 2 · June 2022 · Q07.3 · 2 marks

Suggest how antibodies binding to the sarcolemma in myasthenia gravis weaken contraction.

Question text: myasthenia gravis (MG) is an autoimmune disease in which antibodies bind to the sarcolemma (postsynaptic membrane) of neuromuscular junctions, weakening muscle contraction; Mestinon inhibits acetylcholinesterase. Question asks you to suggest and explain how MG weakens contraction, without details of muscle contraction, 2 marks.
Show the mark scheme Mark scheme: less or no acetylcholine binds to receptors; less or no depolarisation, fewer or no action potentials, or fewer sodium ions enter to reach threshold. 'Weaker action potentials' is ignored; 'active site' is rejected.

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From the examiners' report: Roughly a third each scored two, one and zero. Say acetylcholine can't bind to the receptors, then fewer action potentials, not weaker ones.

Question 16

A level Paper 2 · June 2022 · Q07.4 · 3 marks · Medium

Explain how an acetylcholinesterase inhibitor helps treat myasthenia gravis.

Question text: Mestinon (which inhibits acetylcholinesterase) can help in the treatment of MG; explain how, 3 marks.
Show the mark scheme Mark scheme: less or no acetylcholine broken down; more acetylcholine attaches to receptors; depolarisation of the sarcolemma, action potentials produced, or enough sodium ions enter to reach threshold. 'Remains attached to receptors for longer' = 2 marks.

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From the examiners' report: About 31% got all three and one in four scored zero. Less acetylcholine broken down means more binds to receptors, so name the receptors, then depolarisation of the sarcolemma.

Question 17

A level Paper 2 · June 2023 · Q02.1 · 5 marks · Medium

Explain how a drug that blocks calcium ion channels at synapses reduces pain.

Question text: glutamate transmits impulses from pain receptors to the brain, and its transmission is similar to that of acetylcholine; ziconotide blocks the calcium ion channels at some glutamate synapses. Question asks how ziconotide reduces severe, constant pain, 5 marks.
Show the mark scheme Mark scheme: fewer calcium ions enter the synaptic knob; fewer vesicles fuse with the presynaptic membrane and less glutamate is released; less glutamate diffuses across the cleft; less attaches to receptors on the postsynaptic membrane; fewer sodium ions enter, so fewer impulses to the brain. Max 4 without no/less/fewer.

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From the examiners' report: Only about 7% got all five and 30% scored zero. Calcium ions can't enter the synaptic knob (not the 'synapse'), then follow the whole sequence with 'less' or 'fewer' at every step, through to fewer sodium ions entering.

Investigating nerve impulses (3.6.2.1)

Question 18

A level Paper 3 · June 2022 · Q02.4 · 2 marks · Hard

Use reaction-time data to calculate the mean speed of nerve impulse transmission.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Ruler-drop investigation: student A catches a falling ruler with eyes shut; Table 3 gives distances fallen of 79, 97, 10 and 94 mm in trials 1 to 4, and Table 4 converts distances to reaction times (10 mm = 45 ms up to 90 mm = 136 ms). Question: the nerve pathway is 175 cm; use the tables to calculate the mean speed of transmission, leaving out Trial 3, 2 marks.
Show the mark scheme Mark scheme: 12.9 or 13 m s⁻¹ = 2 marks. 1 mark for using a reaction time of 136 ms (0.136 s), or for 14.58 (including Trial 3), or for 1.29.

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From the examiners' report: Only 16% got both marks. Speed = distance ÷ time: convert 175 cm to 1.75 m and 136 ms to 0.136 s before you divide.

Where students lose marks (from AQA examiners' reports and mark schemes)

Each point below is followed by wording that gained marks.

  • Sodium ions must enter, not just channels open: On ziconotide and the neuromuscular junction many students said sodium ion channels open but never said sodium ions enter, and the mark scheme says channels opening on its own is not enough. Only about 7% got full marks on each question.

    ✔ Gains credit: "Sodium ions enter (the postsynaptic neurone) leading to depolarisation or an action potential."

  • Calcium ions go into the synaptic knob: On the cholinergic synapse, weaker answers had calcium ions diffusing out of the synaptic knob. On ziconotide, students said calcium ions couldn't enter the 'synapse' or the 'presynaptic membrane', which wasn't credited.

    ✔ Gains credit: "Calcium channels open and calcium ions enter the synaptic knob."

  • Vesicles fuse; acetylcholine crosses the cleft: Weaker answers said the vesicles were released and diffused across to the postsynaptic neurone. On the cholinergic synapse 21% scored zero and only about 17% got all five.

    ✔ Gains credit: "Synaptic vesicles move to or fuse with the presynaptic membrane and release acetylcholine; acetylcholine diffuses across the synaptic cleft."

  • Put the receptors on the postsynaptic membrane: On the neuromuscular junction a significant number wrote 'muscle' instead of sarcolemma or postsynaptic membrane, and on myasthenia gravis and Mestinon many left out 'receptors' altogether. Calling the receptor's binding site an 'active site' is rejected.

    ✔ Gains credit: "Acetylcholine attaches to receptors on the sarcolemma (postsynaptic membrane)."

  • Fewer action potentials, never weaker ones: On myasthenia gravis a significant number said weaker action potentials would be produced, which wasn't credited. On the Pacinian corpuscle graph many ignored Figure 1 and only a quarter used it to explain the all-or-nothing principle.

    ✔ Gains credit: "Less or no depolarisation, or fewer or no action potentials." "An action potential is only produced when threshold is reached; high pressure reached threshold."

  • Three sodium ions out, two potassium ions in: Only 13% got all three on the resting potential. Students sent ions the wrong way, wrote 2 sodium ions out for 3 potassium ions in, or said the pump used diffusion rather than active transport.

    ✔ Gains credit: "Sodium ions actively transported out and potassium ions in; membrane more permeable to potassium ions."

  • Myelin is an electrical insulator: Only 8% got full marks on myelinated axons. Some said myelin gives thermal insulation, and 'impulses jumping from node to node' wasn't credited without depolarisation.

    ✔ Gains credit: "Myelination provides electrical insulation; depolarisation at the nodes of Ranvier (saltatory conduction); in non-myelinated axons depolarisation occurs along the whole length."

  • Hyperpolarised: more sodium ions are needed: Only about 18% got both marks on inhibitory synapses. Students knew the inside becomes more negative but wrote 'more sodium' instead of more sodium ions, or had sodium ions leaving the neurone.

    ✔ Gains credit: "Inside of the postsynaptic neurone is more negative; more sodium ions are required to enter for depolarisation."

Download the questions

Download the PDF pack (18 questions, mark schemes at the end)

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Questions, mark schemes and examiners' report extracts © AQA.

Tom Whitburn
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