Food production Flashcards
What does increasing human population require?
An increased food yield
What do fertilisers include that increases crop yield?
Chemicals such as nitrates
Has the human population increased or decreased?
Increased exponentially
Why has the human population grown?
A decrease in deaths from illnesses or child birth due to medical developments
An increase in ability to feed ourselves due to developments in agriculture
How has farming changed since the Victorian times?
Mechanisation and increased field size increases efficiency
Monocultures - growing one crop over a large area is more efficient
Use of chemicals such as fertilisers, herbicides and pesticides
Improved crop varieties due to crop breeding and GM crops
Intensive farming practices, such as rearing animals in sheds
What are the advantages of monocultures?
Farmland produces more food as only the best variety of crops is grown
It simplifies the sowing and harvesting of the crop as machinery can be used, reducing labour costs
What are the disadvantages of monocultures?
As similar plants are grown close together, pests and diseases spread rapidly, and more pesticides are needed to control them
Because only one plant species is wanted, weeds are killed using herbicides
Important wildlife habitats such as hedgerows, ditches, marshes, ponds and small woodlands are removed to create larger fields
This decreases biodiversity and removes the natural predation of pests that feed on the crop
How can we produce more food from the same area of land?
Increase crop yields
Prevent pests damaging crops
How can we increase food yields?
Use fertilisers
Use GM crops
How can we prevent pests damaging crops?
Use pesticides
Use GM crops
Use biological control
What do plants need to build protein molecules?
Nitrogen, phosphorus and potassium
Why do we need to add fertilisers in a field?
Harvesting crops remove essential nutrients, as they are not returned to the soil via the nitrogen cycle.
Fertilisers are added to replace these nutrients, making the crops grow better and increasing yields.
what do plants need minerals from the soil for?
Build other molecules, such as proteins which they can’t do from photosynthesis
Why are nitrates so important?
Nitrates are used to produce amino acids which are synthesised into plant proteins. Animals consume plants or other animals to obtain amino acids for protein
How are nitrates taken in by plants?
Nitrates dissolved in soil water are then absorbed into plants
What form does nitrogen take?
The form of ammonium (NH4-) and nitrate (NO3-) ions
What form does phosphorus take?
Phosphate ions (PO4 3-)
What form does potassium take?
Potassium ions (K+)
What mineral helps with leaves?
Nitrogen
What mineral helps with roots?
Phosphorus
What mineral helps with flower and fruit growth?
Potassium
How can we solve the problem of eutrophication?
Use less fertilisers especially on land near waterways
Use natural fertilisers like manure and compost, which do not dissolve easily in rainwater
Check the weather forecast before adding fertiliser
Only apply chemical fertiliser when plants are actively growing in the spring
Farmers could use crop rotation or grow legumes to replenish nutrients in the soil
Grow GM crops that need less fertiliser
What is eutrophication?
Excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.
What can pesticides do?
Kill plants and animals which reduce crop yield
How is algal bloom caused?
Fertilisers leaching into freshwater, adding extra and unwanted nutrients.
This increases algal population which causes algal bloom.
What does algal bloom do?
Reduces 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 oxygen availability for other organisms.
What is bioaccumulation?
The build up of toxic substances in living organisms
What can happen to pesticides sprayed onto crops?
They can accumulate in the bodies of organisms over time. As they are passed along the food chain, toxicity increases and can reach lethal levels.
What are some alternative to pesticides?
Biological control and GM crops
What are pests?
Pests feeding on crops reduce crop yield
What happens if a plant can’t photosynthesise?
If a plant can’t photosynthesise due to damaged leaves, it will not grow properly, and crop yield will be reduced
Where does -cide come from?
Latin ‘cida’ meaning killer
What is the problem with pesticides?
They kill a wide variety of non-pests species and can reduce biodiversity
Where does 90% of the world’s nutrition come from?
Crops pollinated by bees
What is biomagnification?
The build up of toxic substances along a food chain
Why was DDT called a miracle?
It killed mosquitos, fleas and other insects. Mosquitos are responsible for malaria, and DDT helped reduce the spread of this disease
What was the problem with DDT?
It is not metabolised in organisms. It is resistant to degradation, it bioaccumulates, and is toxic.
It also spreads easily in the environment, reaching places where it was not used (like Arctica)
POPs are toxic - what does this mean?
Genotoxicity: they can damage DNA and cause mutations
Carcinogenicity: they can cause cancer
Teratogenicity: they can cause birth defects
Immunotoxicity: they can damage your immune system
What does “genetically modified” mean?
Means to add a gene from one organism into another organism
What are the advantages of GM crops?
GM crops grow better, and the resulting crop yield increase can help to support the population
Less chemicals such as pesticides are required, and less water may be required , so less environmental damage and use of resources
What are the disadvantages of using GM crops?
Many regard them as unnatural, as genes are transferred between species
Farmers who don’t use the GM variety can’t compete and go out of business
GM crops that produce their own pesticides or herbicides may contain chemicals that damage our health
Herbicide resistant GM crops can be sprayed with huge quantities of herbicides resulting in more damages to the environment
Genes may escape into the environment due to cross breeding with wild plants
What does biological control use?
Natural predators of a pest species as a way to keep their population size low
Give an example of biological control
The ladybird is a natural predator of the aphid.
They can be introduced to reduce the aphid population to a manageable size
What are the risks of biological control?
Control species might not survive in a new environment
Control species might bring new diseases into the new environment
Control species might become a pest species
