This free quiz has 11 real AQA A-level Biology exam questions on nervous coordination (28 marks, about 35 minutes). It marks itself: the table questions are marked for you, and for written answers you check your work against the real AQA mark scheme.
What the quiz covers (AQA 3.6.2)
the refractory period on a trace from a Pacinian corpuscle's sensory neurone
labelling diagrams of a myelinated motor neurone and a neuromuscular junction
why transmission across a cholinergic synapse is unidirectional
naming and explaining the type of summation shown on a graph
how hyperpolarisation at inhibitory synapses inhibits transmission
how a resting potential is maintained, and why a respiratory inhibitor changes it to 0 mV
why impulses travel faster along myelinated axons, and how an acetylcholinesterase inhibitor helps treat myasthenia gravis
the sequence of events in transmission across a cholinergic synapse (5 marks)
How to use it
Write each written answer in full before you open the mark scheme, then tick only the points you really made. Always write sodium ions or calcium ions, never just “sodium” or “calcium”, and say where things happen, such as receptors on the postsynaptic membrane. For the 5-mark synapse question, set out each step in order and use impulses or depolarisation, never signals or messages.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
Resting potential and the pump. Many students got the direction of the pumped ions wrong, said 2 sodium ions go out for every 3 potassium ions in, or said the pump uses diffusion rather than active transport. Others had ions diffusing the wrong way, and answers that never mentioned ions could score only 1 mark.
✔ Gains credit: there is a higher concentration of potassium ions inside and sodium ions outside, the membrane is more permeable to potassium ions than sodium ions, and sodium ions are actively transported out and potassium ions in (3 Na⁺ out, 2 K⁺ in).
ATP, not “energy”. When a respiratory inhibitor was added, some students ignored it and described an action potential, or said it would block channel proteins. Weaker answers said “energy could not be produced”, and very few explained why the potential ends up at 0 mV.
✔ Gains credit: less ATP is produced, so there is less active transport by the sodium–potassium pump; the concentration gradient is not maintained and ions diffuse until there is no net movement of sodium and potassium ions.
Electrical, not thermal, insulation. Few students said myelin gives electrical insulation, and some said it gives thermal insulation. “Impulses jumping from node to node” was not credited, “messages” or “signals” lost marks, and a significant number said impulses would travel faster when myelin is destroyed.
✔ Gains credit: myelin provides electrical insulation, so there is saltatory conduction; without myelin, depolarisation occurs along the whole length of the axon, so impulses are slowed.
Calcium ions enter. Weak answers wrote about “calcium” crossing the membrane, had calcium ions diffusing out of the knob, or said calcium ions were stopped from entering the “synapse”. Saying that vesicles are released, or that vesicles diffuse across, was rejected.
✔ Gains credit: depolarisation causes calcium ion channels to open, calcium ions diffuse into the presynaptic neurone, and this causes vesicles to fuse with the membrane and release the neurotransmitter.
Receptors on the postsynaptic membrane. Many students said a neurotransmitter attaches but left out the word receptors, or didn't say where the receptors are, writing “muscle” instead of sarcolemma. Calling the binding site an “active site” was rejected.
✔ Gains credit: the neurotransmitter diffuses across and attaches to receptors on the postsynaptic membrane (the sarcolemma at a neuromuscular junction).
Sodium ions must enter. A significant number of students said sodium ion channels open but didn't say that sodium ions then enter. Some wrote about “weaker” action potentials, which was not credited.
✔ Gains credit: sodium ions enter the postsynaptic neurone, leading to depolarisation and an action potential; when less neurotransmitter binds, there is less or no depolarisation.
Hyperpolarisation inhibits. Most students said the inside becomes more negative but were less good at explaining why this inhibits transmission. Weaker answers mentioned calcium ions or sodium ions leaving, and “more sodium” instead of “more sodium ions” did not get the mark.
✔ Gains credit: the inside of the postsynaptic neurone becomes more negative, so more sodium ions are needed to enter to reach threshold for depolarisation, making an action potential less likely.
Keep practising
The other AQA 3.6 self-marking quizzes: Stimuli and receptors · Muscle contraction · Blood glucose · Kidney
Next, topic 3.7: the inheritance quiz
The AQA topic index
weekly AQA group classes: Year 12 on Tuesdays at 5.15pm, Year 13 on Wednesdays or Thursdays at 6.30pm
Questions © AQA, from past A-level and AS Biology papers, with their mark schemes and examiners’ reports.