Life on Earth: Increasing Food Production

Question 1

List the 5 stages of leaching

Answer 1

• Fertilisers can leach into fresh water, adding extra, unwanted nitrates.
• This will increase algal populations and cause algal blooms.
• Algal blooms reduce light levels, killing aquatic plants.

-These dead plants, as well as dead algae, become food for bacteria which increase greatly in number.

• The bacteria use up large quantities of oxygen, reducing the oxygen availability for other organisms.

Question 2

What are pesticides?

Answer 2

Chemicals that are sprayed onto crops to kill pests that reduce crop yield.

Question 3

What are the 3 different types of pesticides?

Answer 3

• Insecticides: Used to kill insect pests.
• Herbicides: Used to kill weeds which compete with crop plants.
• Fungicides: Used to kill fungal infections.

Question 4

What is bioaccumulation?

Answer 4

The build-up of pesticides in the body of organisms - the toxicity of these pesticides is passed through the food chain and increases. This can reach lethal levels for the organisms at the end of the food chain.

Question 5

What is a fertiliser?

Answer 5

Chemicals which are added to soil to provide nutrients to increase crop yield.

Question 6

What is the advantage and disadvantage of pesticides?

Answer 6

• Advantage: Kill pests which would reduce crop yield.
• Disadvantage: Can lead to bioaccumulation in food chains.

Question 7

What is the advantage and disadvantage of fertilisers?

Answer 7

• Advantage: Increases nutrients in soil, which increases crop yield.
• Disadvantage: Can leach into rivers.

Question 8

What is an alternative to fertilisers?

Answer 8

GM Crops: When useful genes are inserted into the cells of crop plants to increase crop yield.

Question 9

What is an alternative to pesticides?

Answer 9

Biological Control: Using a natural predator of the pest to get rid of it.