3.5 food production

Question 1

State the link between human population growth and food demand

Answer 1

As the human population increases a require for more food increases

Question 2

Name two groups of chemicals used to increase food production

Answer 2

Fertilisers and pesticides

Question 3

Identify the chemicals in fertilisers

Answer 3

Fertilisers contain chemicals called nitrates.

Question 4

How does nitrates increase plant growth

Answer 4

Nitrates increase crop yield because they are used by plants to produce amino acids which are needed for protein synthesis.

Question 5

What are the impacts nitrate has on plants

Answer 5

= More amino acid production in plants
= More protein synthesis meaning more new cells/cell growth
=Bigger plants increases crop yields.

Question 6

Explain how the use of pesticides will maximise crop yield.

Answer 6

Pesticides are used to kill plants and animals that reduce crop yield. For example they kill catipillars that means less leaves will be damaged so there will be more surface area for photosynthesis.

Question 7

Explain the impact of adding fertilisers to the nitrogen cycle

Answer 7

Fertilisers add nitrate to the soil, so there will be more nitrates available for plants to absorb and use to make amino acids and proteins. So an increase in plant growth

Question 8

Describe the impact of fertilisers leaching into fresh water systems

Answer 8

Excess fertiliser being washed into fresh water systems will cause algal blooms. The nitrate in the fertilisers promote plant growth in the water hence the algal population rapidly increasing causing the algal bloom

Question 9

Explain how GM crops can be used to reduce the use of fertilisers

Answer 9

Plant crop species can be genetically modified to make them more effective at growing in soils with lower concentrations of nitrate thus reducing the need for fertilisers

Question 10

Explain the possible role of GM crops in reducing use of pesticicides

Answer 10

Crops can be genetically modified to produce pest resistant varieties which are toxic to insects when eaten. These varieties will not be eaten by insects and so no pesticide will be needed

Question 11

Explain the impacts of algal bloom on the biodiversity in a fresh water ecosystem

Answer 11

• Excess fertiliser can leach into fresh water, adding extra unwanted nitrates
• This results in an increase in algal populations which can cause algal blooms
• Algal blooms reduce light levels killing other aquatic plants which can no longer get light for photosynthesis
• The dead plants and dead algae become a food source for bacteria which then increses the numbers in bacterial populations
• The bacteria then uses up large quantities of oxygen which means organisms die

Question 12

Define the tern bioaccumulation

Answer 12

Bioaccumulation is the build up of toxic substances e.g. DDT, lead and mercury in the bodies of living organisms

Question 13

Explain the consequences of bioaccumulation

Answer 13

Bioaccumulation results in increasing toxin concentrations as the toxin is passed through the food chain. As the concentration of toxin increases at each trophic level it can reach lethal levels of toxicity causing death of organisms

Question 14

Define the term biological control

Answer 14

Biological control is the use of one species to control the population of another species. The species used as the biological control organism is noramlly a predator or a parasite of the species being controlled

Question 15

State the advantages of biological control compares with use of pesticides

Answer 15

Using biological control methods rather than pesticides reduces the use of chemicals in the environment so reducing problems such as toxicity and bioaccumlation