Exam Focus

Exam Focus

Genetic engineering is one of the highest-mark topics in AQA Biology Paper 2 and Edexcel 1BI0/1 (Paper 1). These are the most important areas:

• Process questions (3-5 marks): "Describe how bacteria are genetically engineered to produce human insulin." Use CLIP — Cut (restriction enzyme), Ligase (seals the gene in), Insert (recombinant plasmid into bacteria), Produce (insulin harvested).
• Enzyme roles (2 marks each): Examiners frequently ask separately about restriction enzyme (cuts) and ligase (joins). Be precise — restriction enzyme does not "insert" the gene and ligase does not "cut."
• Evaluate GM crops (6 marks): A classic AO3 question. Present balanced arguments — advantages (yield, reduced pesticide, vitamin enrichment) and disadvantages (gene spread, unknown effects, ethics). Conclude with your own judgement, justified by evidence.
• Sticky ends (Higher, 2 marks): Explain why the same restriction enzyme must be used for both cuts. The answer is complementary sticky ends enabling base pairing and subsequent ligation.

Edexcel 1BI0 style: Edexcel Paper 1 (1BI0/1) frequently uses a real-world genetic engineering application as stimulus — for example, a passage about the development of GM insulin, a description of a golden rice programme, or data on the uptake of GM crops in different countries. Extended "Evaluate" questions require you to use the stimulus data AND your own knowledge. The command word "Suggest" may ask you to propose a reason why a particular approach was used (e.g., "Suggest why bacteria were chosen as the host organism for insulin production"). Edexcel mark schemes credit specific biological reasoning — vague statements such as "it is better" do not earn marks.