Food production

Biology · Ecology. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

Food security means having enough food to feed a population. It is under threat from several directions, and the challenge is to feed everyone by methods that are sustainable, meaning they can continue without damaging the future supply.

Farmers can make food production more efficient by reducing the energy that animals transfer to the environment. Fish stocks are protected by letting enough fish survive to breed.

Biotechnology offers new foods. The fungus Fusarium is grown in fermenters to make mycoprotein, a protein-rich food suitable for vegetarians. Genetically modified crops can give more food or food with better nutritional value, such as golden rice.

Rules to remember

Threats to food security: rising birth rate, changing diets in developed countries, new pests and pathogens, environmental changes (e.g. failed rains), cost of farming inputs, armed conflict.
Intensive farming: animals are kept in warm sheds with limited movement, so less energy is transferred to the surroundings and more food becomes biomass. Some are fed high-protein food to speed up growth.
Ethical objections: the animals cannot behave naturally and disease spreads easily in crowded conditions.
Fishing quotas limit the mass of fish that may be caught. Larger net mesh lets young fish escape to grow and breed.
Mycoprotein: Fusarium is grown on glucose syrup in aerobic conditions, then the biomass is harvested and purified.
GM bacteria make human insulin, which is harvested and purified to treat diabetes.

Common mistake

A bigger mesh size does not catch more fish. The holes are larger, so small young fish swim through and only the larger adults are caught.

Worked example

Pigs kept indoors in warm pens gain 3.0 kg of biomass for every 10 kg of feed. Pigs kept outdoors gain 2.0 kg for every 10 kg of feed. Compare the efficiencies and explain the difference.

Indoors: (3.0 ÷ 10) × 100 = 30%.
Outdoors: (2.0 ÷ 10) × 100 = 20%.
Outdoor pigs move more and must keep warm, so they use more of their food in respiration.
Less of the food is left to build new biomass.

Answer: Indoor pigs are more efficient (30% against 20%) because less energy is transferred to the environment.

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