GM Crops — Genetic Engineering | IGCSE Biology

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 10% of your exam marks.

increasing

Medium

Increasing10%

Insulin production by bacteria and GM crops are growing in exam frequency.

Genetic engineering of plants has produced crops with useful new traits.

Common GM traits in crops

Trait	Source of gene	Why it matters
Insect resistance	The Bt gene from the bacterium Bacillus thuringiensis makes a protein toxic to caterpillars but harmless to humans	The plant produces its own insecticide; less chemical pesticide needed; less crop loss
Herbicide resistance	Genes that allow the plant to break down a specific weedkiller	Farmers can spray the herbicide on the whole field, killing weeds but not the crop
Drought tolerance	Genes that help the plant cope with low water

Advantages of GM crops

Advantage	Explanation
Higher yields	Less crop lost to pests, weeds and disease
Less pesticide use	Bt crops produce their own insecticide; less chemical needed
Reduced labour and cost for farmers	Herbicide-resistant crops are easier to weed
Better nutrition	Crops like golden rice can deliver missing vitamins to populations who need them
Drought tolerance	Allows farming in dry regions that traditional varieties cannot tolerate

Disadvantages and concerns

Concern	Explanation
Cost	GM seeds are more expensive; large agribusinesses develop them and charge accordingly. Small farmers may be priced out
Cross-contamination	Pollen from GM crops can fertilise wild relatives or organic neighbouring crops, spreading the engineered genes
Loss of biodiversity	Heavy use of herbicide-resistant crops kills off most weeds in the field, reducing food for insects and the birds that eat them
Pest resistance	Insects can evolve resistance to the Bt toxin if they are exposed to it constantly (natural selection in action: see topic 14)

The scientific consensus is that current GM crops are safe to eat. The bigger debates are about social, economic and environmental impacts rather than direct health risks.