OCR 2023 Biology B H422/02: Scientific literacy in biology A Level Question Paper & Mark Scheme (Merged)

2 OCR 2023 1 This question is based on the Advance Notice Article ‘Development of therapeutic antibodies for the treatment of disease’. (a) (i) State what is meant by the term antigen. ........................................................................................................................................... . ..................................................................................................................................[1] (ii) Scientists can combine antibody fragments using phage display to produce many different antibodies, each specific to a different antigen. Using the abbreviations from Fig. 1 in the Advance Notice Article, explain how combining antibody fragments allows scientists to produce many different antibodies, each specific to a different antigen. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... . ..................................................................................................................................[2] (iii) The B cell receptor is an IgG molecule with the same structure as the human IgG shown in Fig. 1 in the Advance Notice Article. Use an abbreviation from Fig. 1 to identify the part of the B cell receptor that will be attached to the cell surface membrane of a B cell. . ..................................................................................................................................[1] 3 OCR 2023 Turn over (b) (i) Explain why mouse monoclonal antibodies (mAbs) have been largely replaced as therapeutic antibodies by humanised or fully human mAbs. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... . ..................................................................................................................................[2] (ii) Explain why the Fab and scFv antibody fragments shown in Fig. 1 are effective as neutralizing or agglutinating antibodies but are less effective as opsonins or in activation of complement. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... . ..................................................................................................................................[2] 4 OCR 2023 (c) (i) Describe how therapeutic mAbs can be used in cancer treatment. ..................................................................................................