A-LevelBiologyBiological moleculesOct/Nov 2009Paper 1 Q121 Mark
HIV-1 protease is an enzyme produced by the HIV virus. Two identical chains of 99 amino acids form the enzyme. In each chain, amino acids 25, 26 and 27 in the sequence form part of the active site. Which orders of protein structure control the shape of the active site?
Aprimary, secondary, tertiary and quaternary
Bprimary, secondary and tertiary only
Cprimary and quaternary only
Dquaternary only
✓ Correct Answer
The correct answer is A: primary, secondary, tertiary and quaternary
📋 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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