A-LevelBiologyTransport in mammalsOct/Nov 2019Paper 1 Q311 Mark
The graph shows oxygen dissociation curves of haemoglobin at two different carbon dioxide concentrations. The partial pressure of oxygen in the lungs is 100 mmHg. The partial pressure of oxygen in metabolically active tissues is 35 mmHg. [Figure 31.1] What is the percentage saturation of haemoglobin with oxygen at the lungs and in metabolically active tissues?
Alungs: 92, metabolically active tissue: 40
Blungs: 92, metabolically active tissue: 66
Clungs: 94, metabolically active tissue: 40
Dlungs: 94, metabolically active tissue: 66
✓ Correct Answer
The correct answer is C: lungs: 94, metabolically active tissue: 40
📋 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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