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A-LevelBiologyEnzymesFeb/Mar 2018Paper 1 Q141 Mark

The diagram shows an enzyme, its substrate and an enzyme/substrate complex. [Figure showing enzyme, substrate, and enzyme/substrate complex] Which statement explains how the substrate is able to enter the active site of the enzyme?

AContact between the substrate and the enzyme causes a change in the enzyme shape.
BThe shape of the active site and the shape of the substrate are complementary.
CThe substrate within the active site forms hydrogen bonds with amino acids.
DWhen the enzyme/substrate complex forms, the tertiary structure of the enzyme changes.

✓ Correct Answer

The correct answer is A: Contact between the substrate and the enzyme causes a change in the enzyme shape.

📋 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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About This A-Level Biology Question

Topic

This multiple-choice question tests Enzymes in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology Feb/Mar 2018 examination, Paper 1 Variant 2.

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