What topic does this question test?

This question tests Biological molecules in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Which exam paper is this question from?

This question appeared in the Cambridge A-Level Biology May/June 2016 examination, Paper 1 Variant 2 (9700_s16_qp_12.pdf).

A-LevelBiologyBiological moleculesMay/June 2016Paper 1 Q81 Mark

Which set of statements correctly describes haemoglobin?

Afour polypeptide chains, each containing a haem group; iron ions can associate with oxygen forming oxyhaemoglobin; in each chain, hydrophobic R groups of amino acids point towards the centre of the molecule; at 50% saturation, two oxygen molecules are transported by the molecule

Bpolypeptide chains interact to produce a globular chain; each chain contains a haem group of amino acids surrounding an iron ion; consists of two identical alpha chains and two identical beta chains; each chain can transport an oxygen molecule

Cpolypeptide chains interact to produce an almost spherical molecule; an iron ion is present within each haem group; quaternary structure has two alpha chains and two beta chains; each molecule can transport a total of four oxygen atoms

Dpolypeptide chains produce a loose helical shape, which folds to form a spherical molecule; iron ions in the molecule can bind reversibly with oxygen; in each chain, hydrophobic R groups of amino acids surround the iron ion; each molecule can transport a total of eight oxygen atoms

✓ Correct Answer

The correct answer is A: four polypeptide chains, each containing a haem group; iron ions can associate with oxygen forming oxyhaemoglobin; in each chain, hydrophobic R groups of amino acids point towards the centre of the molecule; at 50% saturation, two oxygen molecules are transported by the molecule

📋 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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Which set of statements correctly describes haemoglobin?

✓ Correct Answer

📋 Examiner Report & Trap Analysis

🎯 Mark Scheme Breakdown

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