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3.6.2
Nervous Coordination
Analytical deep dive — question counts, mark distribution, mastery curves, command-word breakdowns, and examiner narrative analysis.
Questions
32
Total marks
91
Marks / Q
2.8
Accessibility
63.7%
Mastery
22.4%
Student strength
43.5%
01
At a glance
3.6.2 · Nervous Coordination
8YRSYNTHESIS
3.6.2 (Nervous Coordination) appeared in 8 of the 8 years between 2017 and 2024, contributing 32 questions and 91 marks across Papers 1, 2 and 3. APPLICATION dominates the mark distribution at 62.6% of total marks. The accessibility–mastery gap sits at 41.3 percentage points (63.7% vs 22.4%) — most students reach partial credit, but full marks remain harder to secure. The largest single question observed is worth 5 marks, signalling that AQA expects complete hierarchical accounts in this sub-section. Mastery varied year-to-year, lowest in 2023 (18.2%) and highest in 2018 (33.3%). Calculation marks are a small share (4.4%) but typically sit at the lower end of the mastery distribution.
Access–mastery gap
+41 pp
Lowest mastery
2023 · 18.2%
Highest mastery
2018 · 33.3%
02
Question type split
By marks · compound to dominant
91MARKS
91
marks
Application62.6%57 marks
Knowledge33.0%30 marks
Calculation4.4%4 marks
(by marks; compound rows assigned to dominant type):
03
Credit terms — quick reference
Mark scheme tier-locked
37TERMS
Tier 1 · Always credit
sodium ionsdepolarisationSANaction potentialreceptorsthresholdchemoreceptorscardiac centrepresynaptic membrane
Tier 2 · Sometimes credit
acetylcholineneurotransmitteraction potentialsactive transportimpulsesmedullasympathetic nervous systemfacilitated diffusionvesiclesATPpostsynaptic membranehyperpolarisationmore negativesaltatory conductionnodes of Ranvierneuromuscular junctionsarcolemmasynaptic cleft
Reject · Never credit
signalsmessagesactive sitesignals/messages (for impulses)an impulse (singular)chemoreceptors detect oxygennon-sodium ionscarrier proteinsrelease of vesiclescrossing the membrane
04
Question patterns
Recurring formats & tariff structure
0PARAGRAPHS
05
Year-over-year presence
P1 + P3 · 2017–2024
8YEARS
| Year | Questions | Total marks | Mean accessibility | Mean mastery |
|---|---|---|---|---|
| 2017 | 4 | 12 | 63.8% | 20.0% |
| 2018 | 3 | 8 | 83.0% | 33.3% |
| 2019 | 5 | 12 | 61.8% | 23.8% |
| 2020 | 2 | 9 | — COVID | — COVID |
| 2021 | 3 | 9 | — COVID | — COVID |
| 2022 | 6 | 14 | 58.0% | 23.5% |
| 2023 | 6 | 17 | 62.2% | 18.2% |
| 2024 | 3 | 10 | 62.0% | 19.0% |
06
Mark scheme intelligence
2017–2024 mark scheme corpus
39TERMS
Tier 1 — frequently credited
| Term | Times credited | Years | Notes |
|---|---|---|---|
| sodium ions | 8 | 2017, 2018, 2021, 2022, 2023, 2024 | |
| depolarisation | 8 | 2017, 2018, 2020, 2021, 2022, 2024 | |
| SAN | 6 | 2017, 2019, 2020, 2023, 2024 | |
| action potential | 6 | 2017, 2018, 2020, 2022 | |
| receptors | 5 | 2017, 2018, 2022, 2023 | |
| threshold | 4 | 2017, 2018, 2022, 2024 | |
| chemoreceptors | 3 | 2017, 2020, 2023 | |
| cardiac centre | 3 | 2017, 2020, 2023 | |
| presynaptic membrane | 3 | 2017, 2020, 2023 |
Tier 2 — sometimes credited
| Term | Times credited | Years | Notes |
|---|---|---|---|
| acetylcholine | 4 | 2017, 2022 | |
| neurotransmitter | 4 | 2017, 2022 | |
| action potentials | 3 | 2017, 2019 | |
| active transport | 3 | 2017, 2021 | |
| impulses | 3 | 2019, 2023 | |
| medulla | 2 | 2017, 2023 | |
| sympathetic nervous system | 2 | 2017, 2019 | |
| facilitated diffusion | 2 | 2017, 2021 | |
| vesicles | 2 | 2017 | |
| ATP | 2 | 2017, 2021 | |
| postsynaptic membrane | 2 | 2018, 2023 | |
| hyperpolarisation | 2 | 2018, 2024 | |
| more negative | 2 | 2018, 2024 | |
| saltatory conduction | 2 | 2019, 2021 | |
| nodes of Ranvier | 2 | 2019, 2021 |
Commonly rejected language
| Term | Times rejected | Years | Why rejected |
|---|---|---|---|
| signals | 4 | 2017, 2019, 2023, 2024 | |
| messages | 3 | 2017, 2023, 2024 | |
| active site | 2 | 2018, 2022 | |
| signals/messages (for impulses) | 2 | 2020 | |
| an impulse (singular) | 1 | 2017 | |
| chemoreceptors detect oxygen | 1 | 2017 | |
| non-sodium ions | 1 | 2017 | |
| carrier proteins | 1 | 2017 | |
| release of vesicles | 1 | 2017 | |
| crossing the membrane | 1 | 2017 | |
| produce energy | 1 | 2017 | |
| making energy | 1 | 2017 | |
| receptors release dopamine | 1 | 2018 | |
| messages/signals (even alongside impulses); impulses to other neurons alone without slowing | 1 | 2019 | |
| no impulses (too extreme); messages/signals; changes in impulses from SAN (direction reversed — must be impulses to SAN) | 1 | 2019 |
Marks in this sub-section are typically awarded for precise terminology and correct application of biological principles. Sequential mark schemes — where each mark requires building on the previous one — are common in multi-mark questions; stating the first step without progression rarely earns more than one mark. Calculation marks are typically split between method (correct setup and value extraction) and answer (accurate numerical result), allowing partial credit when arithmetic errors occur.
07
Where students lose marks
Examiner-anchored error patterns
3CASE STUDIES
Conceptual errors
- Sodium ion channels opened but sodium ion entry not stated — this was the single most consistent error pattern across synaptic transmission questions; in 2017, 2018, and 2022, students correctly identified that sodium channels open but then failed to state that sodium ions enter the postsynaptic neurone; the mark requires the movement of ions, not just the opening of channels; naming the channel without naming the consequence earned no mark at that point (2017 P2 Q10.1, 2018 P2 Q07.1, 2022 P2 Q07.2)
- Chemoreceptors described as detecting oxygen rather than carbon dioxide — in 2017, a question on respiratory control saw students state that chemoreceptors in the medulla detect a fall in oxygen; the medullary chemoreceptors primarily detect rising CO₂ (and associated falling pH); stating that they detect oxygen reflects a persistent conflation of oxygen and carbon dioxide roles in respiratory regulation (2017 P2 Q01.1)
- Heart rate irregularity explained by changes in impulses from the SAN rather than to it — in 2019, when applying Guillain-Barré syndrome to cardiac control, only 4% achieved maximum marks; the most concentrated error was describing impulses leaving the SAN as affected; the question required explaining that impulses from the autonomic nervous system to the SAN are disrupted, altering pacemaker activity; reversing the direction made the answer mechanistically wrong (2019 P2 Q10.2)
- Higher P value incorrectly associated with greater disease risk — in 2024, many students concluded that a high LDL concentration was the highest risk factor for atrial fibrillation because it had the highest P value in the table; a higher P value indicates the difference is less likely to be statistically significant; students who associated higher P values with stronger associations scored zero on the data interpretation question (2024 P2 Q06.2)
Vocabulary errors
- "Signals" or "messages" used instead of "impulses" or "action potentials" — this rejection appeared across 2017, 2019, 2023, and 2024 and was the dominant vocabulary error in this sub-section; "signals" and "messages" have no biological precision for describing nerve impulse transmission; where a question asked about increased cardiac output, writing "more impulses" was required, and "more signals" earned nothing (2017 P2 Q01.1, 2023 P2 Q10.5)
- "Active site" used instead of "receptor" or "binding site" in synapse questions — this error was penalised in 2018 and 2022; active sites are features of enzymes; receptors on postsynaptic membranes have binding sites, not active sites; the distinction matters because receptors do not catalyse reactions (2018 P2 Q07.2, 2022 P2 Q07.3)
- Ca²⁺ entering "synapse" or "presynaptic membrane" instead of "synaptic knob" — in 2023, a question on synaptic transmission requiring calcium ion entry used "synapse" or "presynaptic membrane" as the location rather than the synaptic knob; the synaptic knob is the specific structure through which Ca²⁺ enters to trigger vesicle fusion; using the broader term was penalised (2023 P2 Q02.1)
Application errors
- Reaction time conflated with nerve conduction speed — in 2022, a question asking why reaction time is longer than the time calculated from nerve conduction speed alone was answered by students who cited temperature or axon diameter; these factors affect conduction speed, but the question required identifying additional time components — synaptic delay, photoreceptor activation time, muscle contraction latency — that make reaction time longer than a pure conduction calculation suggests; only 0.2% scored all three marks (2022 P3 Q02.5)
- Temporal summation confused with spatial summation — in 2022, about a quarter of students misidentified the type of summation shown in a graph where repeated stimuli from the same presynaptic neurone built up an EPSP over time; temporal summation involves repeated signals from the same neurone over time; spatial summation involves simultaneous signals from multiple neurones; students who named the correct type but described the wrong mechanism earned no marks (2022 P2 Q07.2)
- Drug described as a protein digested by proteases when it was a single-stranded DNA molecule — in 2019, a question about a DNA-based drug asked why oral administration would not work; many students referred to the drug as a protein that would be digested by proteases; the passage stated the drug was single-stranded DNA; the correct mechanism was that nucleases or stomach acid would degrade the DNA, not proteases (2019 P2 Q10.3)
High-impact failures · examiner narrative
2017 P2 Q01.14 marks
Nervous control of increased ventilation rate during exercise. Over 25% of students scored zero despite this being mainly recall. The dominant failures: describing chemoreceptors as detecting oxygen rather than CO₂; using "messages" or "signals" rather than impulses; describing the frequency increase in impulses correctly for the first step but failing to connect the chemoreceptor → medulla → effector chain; and omitting the increase in impulse frequency from the medullary centre to the diaphragm and intercostal muscles. Only 10% scored maximum marks.
2022 P3 Q02.53 marks
Factors making reaction time longer than nerve conduction time. Only 0.2% scored all three marks; 2% scored two marks. Students who repeated answers from a previous part of the question, or who cited axon diameter or temperature (relevant to conduction speed, not to the reaction time discrepancy), scored zero. Valid answers required identifying that synaptic transmission takes time, that photoreceptor activation has a latency, and that neuromuscular junction transmission and muscle contraction add further delay. The examiner noted that confusing reaction time with conduction speed was the conceptual error underlying most failed responses.
2023 P2 Q02.15 marks
Synaptic transmission blocked by a drug preventing Ca²⁺ entry. Only 7% scored all five marks; 30% scored zero. Students described Ca²⁺ entering "the synapse" rather than the synaptic knob, losing precision. Many omitted the "no/fewer" qualifier — writing that vesicles fuse rather than that fewer or no vesicles fuse — when the scenario specifically required describing a reduced or absent response. The receptor on the postsynaptic membrane was frequently omitted, losing the fourth mark. The question was described as an excellent discriminator because it required the full transmission chain under a novel inhibition scenario, and students who had memorised the standard chain without understanding it could not adapt.
08
Difficulty signals
Performance metric synthesis
41PP GAP
Mean accessibility
63.7%
Mean mastery
22.4%
Mean student strength
43.5%
The accessibility–mastery gap of 41.3 percentage points characterises this sub-section's difficulty profile. Most students reach partial credit; full marks remain harder to achieve. Within 3.6 (Organisms respond to changes in their environments), 3.6.2 ranks 1 of 4 sub-sections by mean mastery (1 = hardest). Mastery trajectory is falling across the cohort window: 20.0% in 2017 → 19.0% in 2024 (-1.0 percentage points). Mean mastery was lowest in 2023 (18.2%) and highest in 2018 (33.3%).