Exam Tips: Genetic Engineering

Be precise about enzyme roles: Restriction enzyme CUTS. Ligase JOINS. Never say "restriction enzyme inserts the gene" or "ligase cuts the plasmid." Swapping these roles is the most common error on this topic.

For evaluation questions, always give both sides: A question asking you to "evaluate" GM crops requires advantages AND disadvantages. A one-sided answer cannot score the top marks. End with a justified conclusion: "Overall, I think... because..."

Use the insulin example as your model answer: It is the most examined application. Know it step by step: identify insulin gene → restriction enzyme cuts it from chromosome → same enzyme cuts plasmid → ligase seals gene into plasmid → bacteria take up recombinant plasmid → bacteria cultured → insulin harvested.

Distinguish genetic engineering from selective breeding: Genetic engineering moves individual genes between unrelated species in one generation. Selective breeding works within a species over many generations selecting existing variation. Examiners like comparison questions — have clear contrast points ready.

Safety of GM food — nuanced answer: Do not say "GM food is proven safe" or "GM food is dangerous." The correct AQA answer is: there is currently no scientific evidence that approved GM foods are harmful to human health, but there are legitimate environmental and ethical concerns about their use that are still debated.