A-LevelBiologyImmunity9700/12 · Oct/Nov 2025 · 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?

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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

C: form an antigen-binding site: R and S, have identical amino acid sequences: U and V

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