Exam Focus

Exam Focus

Monoclonal antibodies appear in Higher-tier questions across major specifications. Edexcel 1BI0 Paper 1 (Topic 5: Health, Disease and Medicine) includes monoclonal antibodies most commonly via application questions — you may be given a description of a new diagnostic test or treatment and asked to "Suggest" how monoclonal antibodies are being used, or to "Explain" the advantages of using them. Hybridoma production and specific applications (pregnancy test, cancer treatment) are the most common question formats. Edexcel also tests the ethical considerations of animal use in production.

• Hybridoma production (4-5 marks): Must include: mouse immunised with antigen → B cells extracted from spleen → fused with myeloma cells → hybridoma cells selected → cloned → mass produced. The reason for each step is important.
• Pregnancy test mechanism (3-4 marks): hCG in urine → binds free antibodies (with colour marker) → complex travels to test line → captured by immobilised anti-hCG antibodies → coloured line forms. Must explain WHY each component exists.
• Advantages of monoclonal over polyclonal (2-3 marks): Specificity (one antigen), consistency (all identical), unlimited supply. Link each advantage to an application.
• Ethical considerations (2 marks): Animal welfare (mice used in production), cost/accessibility, long-term safety unknown. Balance with benefits in evaluation questions.

Common mark losses: Confusing monoclonal (identical, one clone) with polyclonal (mixed, many clones). Saying hybridoma = B cell + T cell (it is B cell + myeloma/cancer cell). Describing the pregnancy test as detecting "pregnancy" rather than the specific hCG hormone.