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A-LevelBiologyEnzymesMay/June 2023Paper 1 Q131 Mark

CYP3A4 is an important enzyme in the human digestive system where it is needed to break down a range of different toxins. The activity of CYP3A4 has been shown to be reduced by substances called furanocoumarins. Furanocoumarins are found in some fruits and so dangerous concentrations of toxins may develop in the human digestive system when fruits containing furanocoumarins are eaten. From the information provided, what can be concluded about molecules of the enzyme CYP3A4?

AThey lower the activation energy of the toxin breakdown reactions.
BThey bind specifically through the active site to a substrate found in some fruits.
CThey change permanently when acted upon by furanocoumarin molecules.
DThey resume normal activity when concentrations of furanocoumarins decrease.

✓ Correct Answer

The correct answer is A: They lower the activation energy of the toxin breakdown reactions.

📋 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 May/June 2023 examination, Paper 1 Variant 2.

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