Food security and the factors that threaten it, methods used to increase food production including fertilisers, pest control and intensive farming, biological control, the use of genetically modified crops, and sustainable approaches to feeding a growing human population.

What this dot point is asking

OCR wants you to explain food security and what threatens it, describe the methods used to increase food production (fertilisers, pest control, intensive farming, GM crops), explain biological control, and evaluate sustainable ways of feeding a growing population.

Food security

Several factors threaten food security, and OCR expects you to be able to list and explain them:

• A rising global population, so more food is needed.
• Changing diets in developed countries, where more meat and fish are eaten (which is less efficient than eating plants directly).
• New pests and pathogens that damage crops and livestock.
• The cost of farming (fuel, fertiliser, machinery) and conflict that disrupts food supply.
• Environmental change, such as drought or flooding, reducing harvests.

Increasing food production

To feed more people, farmers use methods that raise the yield from a given area of land:

• Fertilisers add minerals, especially nitrates, to the soil so crops grow faster and bigger. (This links to the nitrogen cycle: nitrates are needed to make proteins.)
• Pesticides kill insect pests and herbicides kill weeds, so less of the crop is lost to damage and competition.
• Intensive (factory) farming of animals keeps them warm and limits their movement, so more of the energy from their food goes into growth rather than heat and movement, increasing meat or egg production.
• Selective breeding and GM crops produce higher-yielding, pest-resistant or faster-growing varieties.

Biological control

For example, ladybirds may be introduced to eat aphids that damage a crop. The advantages are that it does not pollute, is specific to the pest, and does not usually need repeating once established. The disadvantages are that it works slowly, may not remove the pest completely, and the introduced species could itself become a pest or upset the food web. Because of this, farmers often combine biological control with careful chemical use.

GM crops and sustainability

Genetically modified crops can be engineered for higher yields, resistance to pests, disease or herbicides, or added nutrients (such as golden rice with extra vitamin A). They can raise food production and reduce pesticide use, but raise concerns about effects on health, the environment (for example GM genes spreading or harming insects) and the control of seed by companies, so an evaluation must weigh both sides.

Many high-yield methods have environmental costs: fertilisers washed into rivers cause eutrophication (excess nutrients lead to algal blooms, which block light and use up oxygen as they decay, killing fish); pesticides can harm pollinators and accumulate in food chains; and intensive farming raises animal-welfare and disease concerns. Sustainable food production tries to maximise yield while limiting this damage, for example by using fertilisers and pesticides carefully, rotating crops, and protecting pollinators.