Food production

Food security is having enough food to feed a population.

The biological factors threatening it are:

• the increasing birth rate, which has threatened food security in some countries • changing diets in developed countries, meaning scarce food resources are transported around the world • new pests and pathogens that affect farming • environmental changes that affect food production, such as widespread famine when the rains fail • the cost of agricultural inputs • conflicts that affect the availability of water or food.

Sustainable methods must be found to feed all people on Earth.

Interpreting population and food production statistics is examined directly, and the trap is comparing the wrong things. Food production rising does not by itself mean food security is improving — if the population is rising faster, food per person is falling. Work out food per person where you can, and check whether the figures are for the same years and the same region before drawing a conclusion.

The efficiency of food production can be improved by restricting energy transfer from food animals to the environment. This can be done by limiting their movement and by controlling the temperature of their surroundings. Some animals are also fed high protein foods to increase growth.

The biology behind it follows straight from trophic levels: an animal that moves less respires less, and one kept warm does not need to release energy to maintain its body temperature. Both mean more of the biomass it eats is built into its body rather than transferred to the surroundings, so the transfer between trophic levels is more efficient.

Some people have ethical objections to modern intensive farming methods, and an evaluation question expects that to be part of the answer rather than an afterthought. The objection is not that the technique fails — it works, which is the point — but that the cost is borne by the animals, and that cheapness and welfare are being traded against each other. Reaching a judgement, and saying what you weighed, is what earns the final mark.

Fish stocks in the oceans are declining. It is important to maintain fish stocks at a level where breeding continues, or certain species may disappear altogether in some areas.

Control of net size and the introduction of fishing quotas play important roles in conserving fish stocks at a sustainable level.

How each one works is the examinable part. A larger mesh size lets young fish escape, so they survive to breed before they can be caught — the stock replaces itself. Quotas limit the mass of fish that may be landed, so fewer are removed than the population can replace. Both aim at the same thing: taking no more than the stock can regrow.

Modern biotechnology techniques enable large quantities of microorganisms to be cultured for food.

The fungus Fusarium is useful for producing mycoprotein, a protein-rich food suitable for vegetarians. The fungus is grown on glucose syrup, in aerobic conditions, and the biomass is harvested and purified. Learn those conditions — glucose syrup as the food source, and aerobic, because the fungus respires aerobically to grow.

A genetically modified bacterium produces human insulin. When harvested and purified, this is used to treat people with diabetes.

GM crops could provide more food, or food with an improved nutritional value, such as golden rice.

Asked for biotechnical and agricultural solutions to the demands of a growing population, take them in order of what each actually solves. Mycoprotein produces protein without an animal, so it avoids the 10% loss at a trophic level entirely. GM crops can raise yield or add a missing nutrient — golden rice was developed to supply vitamin A where deficiency causes blindness. And GM bacteria make medicines that were previously extracted from animals, in any quantity needed.

The objections to genetic engineering still apply to the GM examples, and a complete answer acknowledges them rather than presenting the technology as settled.