A-LevelBiologyGas exchangeFeb/Mar 2018Paper 1 Q311 Mark
Which of these statements about the formation of haemoglobinic acid are correct? 1 It depends on the formation of carbaminohaemoglobin. 2 It removes excess hydrogen ions preventing the blood becoming too acidic. 3 It is linked to the action of carbonic anhydrase.
A1, 2 and 3
B1 and 2 only
C1 only
D2 and 3 only
✓ Correct Answer
The correct answer is D: 2 and 3 only
📋 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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