High concentrations of ethanol can disrupt cell membrane structure and make the cell surface membrane leaky. Yeast cells release ethanol as a waste product of metabolism. Yeast cells can alter the composition of the cell surface membrane to reduce the effect of ethanol. • A saturated fatty acid, X, is replaced by an unsaturated fatty acid, Y. • Y has a shorter hydrocarbon chain than X. • There is an increase in the phospholipid to protein ratio. Which statement would explain why the effect of ethanol is reduced?
✓ Correct Answer
The correct answer is B: An increase in hydrophobic interaction by phospholipid tails improves membrane stability.
📋 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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