Life on Earth - Food Production

Question 1

Ways to increase food yield

Answer 1

• use of pesticides to kill plants and animals which would increase crop yield
• use fertilisers to stop land being leached of minerals
• growing monocultures over large areas
• introducing genetically modified (GM) crops

Question 2

How do fertilisers work?

Answer 2

• nutrients are not replaced by natural nutrient cycling due to the removal of the crop after growth
• fertilisers are added to the soil to increase the levels of nutrients that are available in the soil
• nitrates are taken up by the plants to produce amino acids which are made into plant proteins

Question 3

Nitrogen cycle (explained in words)

Answer 3

• nitrates are absorbed by the plant and made into plant proteins
• animals eat that plants and then convert the plant proteins into animal proteins
• when the animal produces waste or dies bacteria and fungi break the matter down into other nitrogen compounds
• these ‘nitrogen compounds’ are then converted back into to nitrates by bacteria and the process starts again

Question 4

Think about algal bloom

Main Problem with Fertilisers

Answer 4

• fertiliser is added to farm land, when it rains the nutrients run off the land and ends up in a body of water (eg. pond)
• the nitrates in the water allow algae to grow uncontrollably causing algal bloom
• this bloom prevents light getting into the water, killing other plants
• when all the nitrates run out the algae dies off providing food for bacteria
• the bacteria numbers increase dramatically using up lots of oxygen as they multiply
• with the lack of oxygen the animals that live in the water die off, and when algae is all eaten up the number of bacteria cannot be sustained causing them to die off too

Question 5

Advantages and disadvantages of GM crops

Answer 5

advantages:
- increase in food supply
- decrease in reliance on fertilisers

disadvantages:
- could produce super weeds if it goes into environment
- some beleive its a risk to human health

Question 6

Bioaccumulation

Answer 6

increase in concentration of a non-biodegradable chemical (such as DDT) in the cells of the organisms along a food chain

Question 7

GM crops

Answer 7

the crops genome is altered causing them to have certain features. this can can reduce the need for fertilisers but it is quite controversial

e.g. drought resistance, natural pesticide

Question 8

Monoculture

Answer 8

vast cultivated population of one type of crop plant whose members are often genetically the same

Question 9

Pesticide

Answer 9

general name given for a chemical used to kill a pest species

Question 10

Biological Control

Answer 10

reduction of a pest population by the deliberate introduction of one of its natural enemies/predators

Question 11

Algal bloom

Answer 11

result of rapid growth of population of simple water plants eg. aglae

Question 12

Intensive Farming

Answer 12

form of agriculture which gives increased yield by growing monocultures and by ‘battery farming’ animals as well as other methods