AQA GCSE Biology: Food Security and Production

This whole guide is Triple award only. Feeding a growing population sustainably is one of biology's biggest challenges. This guide covers the threats to food security, the ways farming and fishing can be made more efficient and sustainable, and the role of biotechnology. The theme is producing more food while protecting the environment.

Food security

Food security is having enough food to feed a population. It is threatened by several biological factors:

• an increasing birth rate in some countries, so there are more people to feed;
• changing diets in developed countries, so scarce resources are transported around the world;
• new pests and pathogens that damage crops and livestock;
• environmental changes, such as failed rains, causing famine;
• the cost of agricultural inputs, such as fertilisers and machinery;
• conflicts that affect the availability of food and water.

Sustainable methods must be found to feed everyone on Earth.

Efficient farming

The efficiency of food production from animals can be improved by restricting the energy the animals transfer to the environment, so more is available for growth. This is done by limiting their movement (for example by caging them), controlling the temperature of their surroundings (for example keeping them indoors), and feeding them high-protein food. The logic behind all three is a single energy budget. Everything an animal eats is either stored as new tissue, which is the part we eat, or spent on something else. Moving costs energy, and so does keeping warm. Stop the animal moving and it spends less on movement. Keep it warm and it spends less on respiration generating its own heat. Whatever is not spent is available for growth, so more of the food becomes meat.

That is also precisely why the methods are controversial, and a good answer puts the two together rather than treating them as separate lists. The same cage that saves energy prevents normal behaviour. The same shed that holds the temperature steady holds the animals close enough together for disease to spread quickly, which is why antibiotics are used routinely, which in turn drives antibiotic resistance. Efficiency and welfare are not two unrelated issues here; one is bought with the other.

Sustainable fisheries

Fish stocks must not be allowed to fall too low, or there will not be enough fish left to breed, and species could disappear from some areas. Stocks are conserved by:

• controlling net (mesh) sizes, so that younger fish are not caught and can live long enough to reproduce;
• introducing fishing quotas, which limit how many fish are caught so the rest can reproduce.

The two work differently and questions sometimes ask which is better. A mesh size controls which fish are caught: a wider mesh lets the young ones through so they survive to breed at least once. A quota controls how many are caught, regardless of size. Mesh size protects the future of the stock; a quota protects its present numbers, and the two are usually used together because either alone leaves a gap.

The underlying idea is the same one as in any population. If fish are removed faster than they are replaced by breeding, numbers fall, and below a certain point there are too few left to find each other and breed at all. From there the stock does not recover simply because fishing stops.

Biotechnology

Modern biotechnology can produce food in new ways, growing large quantities of microorganisms.

• Mycoprotein is a protein-rich food suitable for vegetarians, made from the fungus Fusarium, which is grown on glucose syrup in aerobic conditions; the biomass is then harvested and purified.
• GM crops can provide more food or food with better nutrition, for example golden rice, which contains beta-carotene to make vitamin A.
• GM bacteria can produce human insulin, which is harvested and purified to treat diabetes.

Microorganisms are used because of how fast they grow. A fungus or a bacterium in a fermenter doubles in hours rather than months, so a small starting culture becomes a large mass of protein very quickly, in a tank rather than on a field, independent of the weather.

The word aerobic in the mycoprotein description is doing real work, so do not drop it. Fusarium is grown on glucose syrup with oxygen supplied, because aerobic respiration releases far more energy per glucose molecule than anaerobic, and that energy is what the fungus uses to grow. Grow it without oxygen and you get ethanol and very little biomass, which is brewing rather than food production.

Golden rice is the example to know for GM crops because it answers a specific problem rather than simply producing more. It has been engineered to make beta-carotene, which the human body converts to vitamin A, and it exists because vitamin A deficiency causes blindness in regions where rice is the staple food. GM questions usually want a named benefit and a named concern, so pair it with the standard objections: unknown effects on health, the escape of inserted genes into wild plants, and the cost of seed to farmers.

How this fits together

Food security completes Topic 7 and the GCSE course, tying ecology to one of the great practical problems of biology: producing enough food for a growing population without destroying the ecosystems we all depend on.