GMOS and human population growth (Edexcel GCSE Biology): Revision Notes

GMOS and human population growth

Crops can be genetically modified to be resistant to insects…

1. This improves crop yields and reduce need for chemical pesticides
2. Bacterium called Bacterium called bacillus thuringiensis which produces a toxin (poison) that kills many of the insect larvae harmful to crops. which produces a toxin (poison) that kills many of the insect larvae harmful to crops.
3. The gene for the Bt toxin inserts into crops eg cotton and corn, produces toxin in their stems and leaves- making them resistant to the insect pests.
4. Toxin is specific to insect pests- harmless to humans, animals and other insects. Long term however the effects are not exposed to bt crops aren't known yet
5. Insects that feed on crops are constantly exposed to the toxin, so there's a danger they'll develop resistance and no longer be killed by it. Farmers try to avoid this happening by using other insectides too.

GMOS can be used to provide more food for people

6. Worlds population is rising rapidly- not slowing down
7. Means that global food production must increase too so that we all have access to enough food that is safe enough to eat and has the right nutrition- "food security"
8. GM crops can be used to increase food production- eg. crops that are genetically engineered to be resistant to pests or to grow better in drought conditions can help improve crop yields
9. Some crops can be engineered to combat certain diseases eg. Golden Rice has been genetically engineered to produce a chemical in the body to vitamin A

Not everyone thinks this is a good idea:

• Many people that go hungry cant afford food. So argument they need to tackle poverty first
• There are fears that countries may become dependent on companies who sell GM seeds
• Sometimes poor soil is the main reason why crops fail, and even GM crops wont survive. Other techniques can also be used to increase food production:

10. Using GMO's is a relatively new way of improving crop yields and it might not be as helpful
11. E.g. If soils poor, applying fertilisers is likely to be the best way to increase yields. Fertilisers contain materials that are essential for plant growth. Eg, nitrates and phosphates. They replace nutrients that have been lost from soil to previous crops. However excess fertilisers can cause problems can cause problems in rivers and lakes through the process of eutrophication
12. Pests can also be controlled without the use of GM crops and chemical pesticides. Biological control methods use of other organisms to reduce past numbers. For example; cane toads were introduced into Australia to eat beetles that were damaging crops

13. Biological control can have longer lasting effects than chemical pesticides and be less harmful to wildlife, but introducing new organisms can cause problems. E.g. can toads are now a pest themselves in Australia because they poison the native species that eat them