A-LevelBiologyCell membranes and transport9700/12 · Oct/Nov 2019 · Q171 Mark
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?
Agreater proportion of phospholipid may increase the entry of ethanol via channel proteins.
BAn increase in hydrophobic interaction by phospholipid tails improves membrane stability.
CAn increase in the proportion of fatty acids with double bonds decreases membrane fluidity.
DThe shorter hydrocarbon chain of Y decreases membrane fluidity.
✓ Correct answer
B: An increase in hydrophobic interaction by phospholipid tails improves membrane stability.
Practise more questions on this topic
Oracle Prep sorts past-paper questions by topic, so you can drill Cell membranes and transport and see which topics are most likely to come up next.
Sign up free →