The table shows some information about the polypeptides that make up haemoglobin. α-globin: total number of amino acid residues in polypeptide chain: 141 position of amino acid cysteine in polypeptide chain: 104 β-globin: total number of amino acid residues in polypeptide chain: 146 position of amino acid cysteine in polypeptide chain: 93 and 112 Scientists studied the region of the β-globin polypeptide chain containing the amino acid cysteine at position 93. They found that: • this region faces outwards when no oxygen is attached to the haem group • this region faces inwards when oxygen is attached to the haem group • replacing cysteine with a different amino acid reduces the Bohr shift. What can be concluded from the information about cysteine in haemoglobin?
✓ Correct Answer
The correct answer is A: More than 1% of the amino acids in one haemoglobin protein are cysteine.
📋 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.
Unlock the Examiner's Analysis
Sign up for free to reveal the full examiner report, trap analysis, and mark scheme breakdown for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep