A-LevelBiologyImmunityMay/June 2020Paper 1 Q391 Mark
Myasthenia gravis is a disease that results from the immune system failing to distinguish between self and non-self. Antibodies bind to a component of the junctions between a muscle and its nerve. What correctly describes Myasthenia gravis?
AImpulses in the nerve to the affected muscle cannot be blocked.
BThe affected muscle cannot be repeatedly stimulated.
CThe affected muscle is permanently stimulated.
DThe nerve to the affected muscle does not carry any nerve impulses.
✓ Correct Answer
The correct answer is B: The affected muscle cannot be repeatedly stimulated.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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