A-LevelBiologyInherited changeMay/June 2021Paper 4 Q79 Marks
(a) Haemoglobin is made of two α-globin chains and two β-globin chains. A person may have a mutation in the gene coding for β-globin. This is due to a base substitution and leads to the production of abnormal β-globin and therefore abnormal haemoglobin. A person who is homozygous for the mutant allele will have a condition called sickle cell anaemia.
📋 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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