How to Revise IGCSE Biology Topic 21: Biotechnology and Genetic Engineering
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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Key point
Know the four steps of genetic engineering (cut, insert, transfer, express). Understand bioreactor conditions for industrial fermentation. Be able to discuss the advantages, disadvantages, and ethical concerns of GM technology.
Topic 21 covers genetic engineering (how genes are transferred and used), fermentation and bioreactors (using microorganisms to make useful products), cloning, and the social and ethical issues surrounding these technologies. Genetic engineering steps are commonly tested.
Priority 1: Genetic engineering steps
1. Identify and cut the desired gene from the donor organism using restriction enzymes. 2. Insert the gene into a vector (usually a bacterial plasmid) using ligase enzyme. 3. Transfer the vector into the host organism (e.g. Bacterium). 4. The host organism expresses the gene and produces the desired protein.
Key example: production of human insulin by bacteria.
Priority 2: Fermentation and bioreactors
Microorganisms (bacteria, yeast, fungi) are grown in bioreactors (fermenters) to produce useful products: antibiotics (penicillin from Penicillium), insulin (from GM bacteria), bread and alcohol (from yeast fermentation). Conditions are carefully controlled: temperature, pH, nutrient supply, oxygen, and waste removal.
Priority 3: Cloning and ethics
Cloning produces genetically identical organisms. Plant cloning (tissue culture / micropropagation) is widely used in agriculture. Animal cloning is more controversial. Ethical concerns about genetic engineering include: safety of GM foods, ecological risks, inequality of access, and the question of whether we should modify living organisms.
Frequently asked questions
Is genetic engineering the same as selective breeding?
No. Genetic engineering directly transfers specific genes between organisms (even different species). Selective breeding crosses organisms with desired traits over many generations within the same or closely related species.
Put the guide into practice
Questions and practical resources
Use a fresh question to check whether the idea can be applied without prompts.