A-LevelBiologyCell membranes and transportOct/Nov 2009Paper 1 Q141 Mark
The diagram shows a red blood cell and the concentrations of ions, in mmol dm⁻³ in and in the cell. [Diagram of a red blood cell showing ion concentrations inside and outside the cell] Which ions are actively transported into and out of the cell?
Ainto cell: Cl⁻, out of cell: K⁺
Binto cell: K⁺, out of cell: Na⁺
Cinto cell: Na⁺, out of cell: Cl⁻
Dinto cell: Na⁺, out of cell: K⁺
✓ Correct Answer
The correct answer is B: into cell: K⁺, out of cell: Na⁺
📋 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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