A-LevelBiologyCell membranes and transportOct/Nov 2014Paper 1 Q181 Mark
The enzyme lactase is found in the membranes of epithelial cells lining the small intestine. The enzyme is formed by a single polypeptide that folds to give three regions. • an active site with the free amino group outside the cell • a short section inside the membrane • a short section inside the cell What type of amino acid would be found in each of the three regions?
Aoutside cell: hydrophilic, inside the membrane: hydrophobic, inside the cell: hydrophilic
Boutside cell: hydrophilic, inside the membrane: hydrophobic, inside the cell: hydrophobic
Coutside cell: hydrophobic, inside the membrane: hydrophilic, inside the cell: hydrophobic
Doutside cell: hydrophobic, inside the membrane: hydrophobic, inside the cell: hydrophilic
✓ Correct Answer
The correct answer is A. This question tests the candidate's understanding of cell membranes and transport within the Biologysyllabus. The examiner's mark scheme requires...
📋 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...
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