Food Security and Sustainable Food Production

Food security is having enough food to feed a population. A country is food-secure when its people can reliably get enough safe, nutritious food. When that supply is unreliable, the population faces shortages, hunger and famine.

The challenge is scale. The human population keeps growing, and every extra person needs feeding from a planet whose farmland, oceans and fresh water are limited. The job of biology here is to identify the biological factors that threaten food security and to find sustainable ways to feed everyone — methods that meet today's needs without using resources up so fast that future generations go short.

Food security: having enough food to feed a population.

This lesson works through four linked questions the AQA specification expects you to answer:

• What biological factors threaten food security? (4.7.5.1)
• How can farming be made more efficient — and why do some object? (4.7.5.2)
• How are fish stocks kept at a sustainable level? (4.7.5.3)
• How does biotechnology help feed a growing population? (4.7.5.4)

Several biological and human factors push food supply below the level a population needs. You should be able to describe each one and explain why it reduces the food available.

Factor	Why it threatens food security
Increasing birth rate	A rising population means more mouths to feed from the same land, so supply per person falls in some countries.
Changing diets in developed countries	As richer countries demand a wider variety of foods, scarce food resources are transported around the world rather than eaten where they are grown.
New pests and pathogens	Pests and diseases that affect farming can destroy crops and livestock, cutting yields.
Environmental change	Changes such as failed rains cause widespread famine in some countries when crops cannot grow.
Cost of agricultural inputs	Seeds, fertiliser, fuel and machinery cost money; when inputs become too expensive, farmers grow less.
Conflict	Wars in some parts of the world disrupt the availability of water and food, and block farming and supply routes.

Exam tip: the command word is usually "describe" or "explain". Naming a factor earns little on its own — say why it reduces the amount of food available.

Because all these pressures act at once, sustainable methods must be found to feed everyone on Earth: farming smarter, fishing within limits, and using biotechnology.

The efficiency of food production can be improved by restricting the transfer of energy from food animals to the environment. To see why this works, recall how energy moves through a food chain.

Only about 10% of the energy (biomass) at one trophic level is passed on to the next. The other ~90% is lost — as heat from respiration, in movement, and in waste. If a farmer can stop an animal losing energy to its surroundings, more of the energy in its food is stored as body mass instead, so the animal grows faster on less food.

Worked example — why limiting movement helps. A pig kept in a small pen cannot run around. Movement requires muscle contraction, which requires respiration, which releases energy as heat to the environment. By limiting movement:

• less energy is used in muscle activity,
• less is lost as heat,
• so more of the energy from its food is transferred into new body tissue (biomass).

Controlling the temperature of the surroundings works the same way. A warm barn means the animal does not have to respire extra glucose just to keep its body temperature up, so again more energy goes into growth. Some animals are also fed high-protein foods to speed up growth, because protein supplies the amino acids needed to build new tissue.

These methods — keeping animals indoors, warm, still and well-fed — are known as intensive or factory farming.

Intensive methods make food production cheaper and faster, but many people have ethical objections to them. You should be able to evaluate both sides.

Advantages	Disadvantages and objections
More food produced from the same resources	Animals kept in small spaces cannot behave naturally
Faster animal growth, so cheaper meat	Crowding can spread disease, so antibiotics may be overused
Less land needed per kilogram of food	Many consider restricting movement cruel
Easier to control conditions and feeding	High-protein feed may use crops that could feed people directly

Evaluate means weigh up both sides and reach a judgement — do not just list points. A strong answer might conclude: intensive farming raises efficiency and lowers cost, but the welfare cost to the animals leads many people to reject it on ethical grounds.

The specification asks you to understand that some people have ethical objections — it does not require you to hold a particular view. Marks come from explaining the objections clearly and balancing them against the efficiency gains.

Fish are a major source of protein, but fish stocks in the oceans are declining because we have caught them faster than they can reproduce. It is important to keep fish stocks at a level where breeding can continue; otherwise some species may disappear altogether in certain areas.

Two conservation measures help stocks recover to a sustainable level:

Measure	How it conserves stocks
Controlling net (mesh) size	A larger mesh lets young, small fish slip through and escape. They survive to breed, while only mature fish are caught.
Fishing quotas	A quota is a legal limit on how much of a species may be caught. It prevents over-fishing and gives the population time to recover.

Worked example — evaluating bigger mesh sizes. Suppose a fishery switches to a wider mesh. Benefit: juvenile fish are not removed, so they grow up and reproduce, and the breeding population recovers. Drawback: fishers catch fewer fish in the short term, reducing their income now. The judgement: a short-term loss in catch protects the long-term survival of the stock, so the measure is sustainable even though it is unpopular at first.

Sustainable fishing: taking fish at a rate that still allows the population to breed and replace itself, so the stock does not collapse.

Modern biotechnology lets us culture (grow) very large quantities of microorganisms for food, and lets us modify organisms to make useful products. These approaches help meet the food demands of a growing population.

Mycoprotein is a protein-rich food suitable for vegetarians. It is made from the fungus Fusarium:

The fungus is grown on glucose syrup, in aerobic conditions; the resulting biomass is harvested and purified to make the food.

Other biotechnology examples use genetic modification (GM) — transferring a gene from one organism into another so the second organism makes a useful product:

Example	What is done	Why it helps
GM bacterium making insulin	A human insulin gene is inserted into a bacterium, which then produces human insulin; this is harvested and purified	Treats people with diabetes
GM crops	Crops are modified to give higher yields or better nutrition	Could provide more food, or food with improved nutritional value
Golden rice	Rice modified to make a precursor of vitamin A	Helps prevent vitamin A deficiency where rice is the staple food

(Extra context — not required by AQA 8461.) GM insulin is sometimes called "human insulin" because the bacterium reads a human gene, so the protein is identical to the insulin a human body makes.

1. Defining food security vaguely

Food security is specifically having enough food to feed a population — not "having good food" or "having a healthy diet". Use the exact definition.

2. Naming factors without explaining them

Listing "war" or "pests" earns little. Say why each one cuts the amount of food available — e.g. conflict disrupts access to water and food and blocks supply.

3. Getting the energy logic backwards

Restricting movement and warming the surroundings reduce energy loss from the animal, so more biomass is built. Students often write that it gives the animal more energy — the energy comes from food; the technique simply stops it being wasted.

4. Confusing the two fisheries measures

Net (mesh) size controls which fish are caught (lets young ones escape to breed); quotas control how many are caught. They are different tools — name the right one.

5. Muddling the biotechnology examples

Fusarium is a fungus grown for mycoprotein on glucose syrup in aerobic conditions. Insulin is made by a GM bacterium. Do not swap the organisms or the products.

6. Saying mycoprotein is grown anaerobically

The fungus needs oxygen — it is cultured in aerobic conditions. Anaerobic conditions would be the wrong answer.