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A-LevelBiologyGas exchangeFeb/Mar 2019Paper 1 Q311 Mark

The graph shows the oxygen dissociation curves of haemoglobin for eight species of mammal. [Figure shows oxygen dissociation curves for 8 mammals, with a key relating numbers 1-8 to decreasing order of size] Which conclusion is consistent with the data shown in the graph?

AThe haemoglobin of larger mammals will combine with oxygen at a lower partial pressure of oxygen than that of smaller mammals.
BThe haemoglobin of larger mammals will release oxygen at a higher partial pressure of oxygen than that of smaller mammals.
CThe metabolic activity of the mammal is directly proportional to the ability of its haemoglobin to release oxygen.
DThe size of the mammal is directly proportional to the ability of its haemoglobin to release oxygen.

✓ Correct Answer

The correct answer is A: The haemoglobin of larger mammals will combine with oxygen at a lower partial pressure of oxygen than that of smaller mammals.

📋 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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About This A-Level Biology Question

Topic

This multiple-choice question tests Gas exchange in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology Feb/Mar 2019 examination, Paper 1 Variant 2.

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