A-LevelBiologyImmunityOct/Nov 2025Paper 1 Q401 Mark
The diagram shows an antibody molecule with some parts labelled. [Diagram of an antibody molecule with parts P, W, V, U, R, S, T labelled] Which row is correct about the parts that form an antigen-binding site and have identical amino acid sequences?
Aform an antigen-binding site: P and Q, have identical amino acid sequences: R and S
Bform an antigen-binding site: Q and V, have identical amino acid sequences: P and S
Cform an antigen-binding site: R and S, have identical amino acid sequences: U and V
Dform an antigen-binding site: U and V, have identical amino acid sequences: Q and R
✓ Correct Answer
The correct answer is C. This question tests the candidate's understanding of immunity within the Biologysyllabus. The examiner's mark scheme requires...
📋 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...
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