A-LevelBiologyCell membranes and transportMay/June 2019Paper 1 Q121 Mark
The fatty acids elaidic acid and oleic acid have exactly the same structural formulae, with one double bond in the chain. However, the shapes of the chains are different, as shown in the diagram. [Figure: Diagrams of elaidic acid and oleic acid] Which row shows the effect of the presence of these fatty acids on the structure and behaviour of a cell surface membrane?
Aelaidic acid: does not fit closely with other fatty acids so that the membrane is less fluid at high temperatures, oleic acid: fits closely with other fatty acids so that the membrane is less fluid at low temperatures
Belaidic acid: does not fit closely with other fatty acids so that the membrane is more fluid at low temperatures, oleic acid: fits closely with other fatty acids so that the membrane is less fluid at low temperatures
Celaidic acid: fits closely with other fatty acids so that the membrane is less fluid at high temperatures, oleic acid: does not fit closely with other fatty acids so that the membrane is more fluid at low temperatures
Delaidic acid: fits closely with other fatty acids so that the membrane is more fluid at low temperatures, oleic acid: does not fit closely with other fatty acids so that the membrane is more fluid at high temperatures
✓ Correct Answer
The correct answer is C. This question tests the candidate's understanding of cell membranes and transport within the Biologysyllabus. The examiner's mark scheme requires...
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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...
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