4BI1
Genetic Engineering
Use of Biological Resources · 6 question types
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 | Crops can be grown in drier regions or use less irrigation |
| Vitamin A production | "Golden rice" carries genes from another plant + a bacterium that produce beta-carotene (a vitamin A precursor) | Could prevent vitamin A deficiency, which causes blindness and death in poor regions |
| Disease resistance | Genes for resistance to specific viral or fungal pathogens | Less crop lost to disease; less need for fungicides |
| Longer shelf life | Genes that slow down ripening | Reduces food waste |
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 |
| Less land needed | Higher yields per hectare reduce pressure on rainforests for new farmland |
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) |
| Dependence on agribusiness | Farmers in poorer countries may become locked into buying seed each year from a single company |
| Long-term human health unknown | GM food has been eaten for decades with no proven harm, but long-term effects are not certain |
| Ethical concerns | Some people feel that humans should not "play God" with the natural genome |
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.