A-LevelBiologyEnzymesOct/Nov 2010Paper 1 Q221 Mark
S and T are products of a biochemical pathway. A different enzyme, coded for specific genes, catalyses each step in the pathway. [Figure 22.1 showing a biochemical pathway with intermediates P, Q, R, S, T and enzymes/genes] What is the possible outcome to the pathway if a mutation in gene 3 leads to an inactive enzyme?
AThere is a decrease in the activity of gene 1 and gene 2.
BThere is an accumulation of product S.
CThere is an increase in the rate of reaction of enzyme 4.
DThere is an increase in the production of T.
✓ Correct Answer
The correct answer is D: There is an increase in the production of T.
📋 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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