Unit 3 - Key Area 5 - Food Production Flashcards
What is required by an increasing human population?
An increasing human population requires an increase in food yield.
What can be used to increase food yield?
Fertilises
Pesticides
What is a fertilisers?
A fertiliser is a chemical that is used by farmers to improve plant growth.
It provides chemicals such as nitrates which increase crop yield.
Describe the role of nitrates
Nitrates dissolved in the soil are absorbed into plants and used to produce amino acids to make plant proteins.
Animals eat the plants and other animals to get amino acids for protein synthesis.
Fertilisers can increase soil nitrate content.
What is leaching and what affect does it have on freshwater systems?
Fertilisers increase the nitrate content of the soil.
Leaching is when fertilisers are washed from the soil into freshwater (after heavy rainfall).
This makes the fresh water ‘over-rich’ in minerals.
Algae populations increase causing an algal bloom.
Algal bloom decreases light levels, killing aquatic plants.
Dead plants and dead algae become food for bacteria which increase in number.
The bacteria use up large quantities of oxygen reducing the oxygen availability for other organisms.
What is a pesticide?
A pesticide is a chemical used to kill plants and animals that reduce crop yield.
What is bioaccumulation and how does it affect organisms in a food chain?
Some pesticides sprayed onto crops accumulate (build up) in the bodies of organisms over time.
This is called bioaccumulation.
As they are passed along food chains, toxicity levels increase and can reach lethal levels.
What is biological pest control? Give examples
Biological control is the deliberate use of natural predators to control pests in farming.
Greenfly reduce crop yield. Ladybirds eat greenfly and can be used as a biological control which increases crop yield.
What are the advantages of biological pest control?
Reduces effects of harmful chemical pesticides that may kill other organisms
Bioaccumulation does not occur
What are the disadvantages of biological pest control?
Only effective in small growing areas
The natural predators may become the pest
What are GM crops and why are they used in pest control? Give examples
Genetically modified crops have had a useful gene from another organism inserted into their cells.
Crops can be genetically modified to reduce or prevent the need for fertilisers or pesticides.
Examples of plants engineered in this way are:
• Maize
- Resistant to insect pests
• Potatoes
- Resistant to fungal blight
What are the advantages of GM crops?
GM crops allow farmers to decrease their use of chemicals without decreasing their yield
GM crops reduce the quantity of crop lost
What are the disadvantages of GM crops?
No guarantee that crops will remain resistant to disease
Some people believe these crops carry a risk to health
