A-LevelBiologyGas exchange9700/12 · Oct/Nov 2014 · Q301 Mark

The graph shows a dissociation curve for haemoglobin. [Figure 30] Which are suitable labels for the x-axis and the y-axis?

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Ax-axis: partial pressure of carbon dioxide, y-axis: percentage of haemoglobin

Bx-axis: partial pressure of oxygen, y-axis: percentage saturation of haemoglobin with oxygen

Cx-axis: percentage of haemoglobin, y-axis: partial pressure of oxygen

Dx-axis: percentage saturation of haemoglobin with oxygen, y-axis: partial pressure of carbon dioxide

✓ Correct answer

B: x-axis: partial pressure of oxygen, y-axis: percentage saturation of haemoglobin with oxygen

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Topic: Gas exchange, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, Oct/Nov 2014 Paper 1 Variant 2, question 30.

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