Unit 3 Food Production

Question 1

Why are fertilisers needed?

Answer 1

They are needed because the human population is increasing so we require and increased food yield which involves the use of fertilisers and pesticides.

Question 2

What do fertilisers do?

Answer 2

They provide chemicals such as nitrates which increase crop yield. They are added to soil to increase the nitrate content of the soil.

Question 3

What do pesticides do?

Answer 3

They kill plants and animals which reduce crop yield.

Question 4

What are nitrates for?

Answer 4

They are dissolved in soil water and are absorbed into plants. Nitrates are used to produce amino acids which are synthesised into plant proteins.

Question 5

Why do animals consume plants?

Answer 5

So that they can obtain amino acids for protein synthesis.

Question 6

What is a problem with fertilisers ?

Answer 6

Leeching.

Question 7

Describe leeching.

Answer 7

Fertilisers can leech into fresh water, adding extra, unwanted nitrates. This will increase algal populations which can cause algal blooms. Alfalfa blooms reduce light levels, killing aquatic plants. These dead plants, as well as dead algae become food for bacteria which will greatly increase their population. These bacteria use up large quantities of oxygen reducing the oxygen availability for other organisms.

Question 8

What can be used to reduce the use of fertilisers?

Answer 8

Genetically modified crops

Question 9

What is the problem with pesticides?

Answer 9

Pesticides sprayed onto crops can accumulate in the bodies of organisms over time. As they are passed along food chains, toxicity increases and can reach lethal levels.

Question 10

What is an alternative to the use of pesticides?

Answer 10

The use of biological controls and genetically modified crops.

Question 11

What is bioaccumulation?

Answer 11

The build up of toxic substances in organisms.