AQA GCSE Biology (8461)

4.7.5 Food production (Bio only)

Food production is the engine that keeps eight billion people fed — but it sits on a knife edge. A growing population, changing diets, new pests, droughts and rising input costs all threaten food security: the simple idea of having enough food for everyone. This page works through the biological tools available to make food production more efficient and sustainable: intensive farming techniques that channel more biomass into meat, fish-stock management using quotas and mesh sizes, mycoprotein from the fungus Fusarium, and genetic modification of crops for traits like drought resistance, pest resistance, higher yield and improved nutrition. You'll also see why eating closer to the producers — a more plant-based diet — feeds far more people per hectare of land than a meat-heavy one. By the end you'll write the exam phrases AQA wants: 'biomass is lost between trophic levels', 'grown in fermentation vats', 'larger mesh size lets small fish escape', and 'drought-resistant / higher yield'.

From the 8461 specification

Food security is having enough food to feed a population. Biological factors which are threatening food security include: the increasing birth rate has threatened food security in some countries; changing diets in developed countries mean 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 occurring in some countries if rainfall is low; the cost of agricultural inputs; conflicts in some parts of the world which affect the availability of water or food. Sustainable methods must be found to feed all people on Earth. The efficiency of food production can be improved by restricting the 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 fed high protein foods to increase growth. Some ethical objections have been raised. 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 conservation of fish stocks at a sustainable level. 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. Modern medical research is exploring the possible use of bacteria to synthesise other useful products. For example, a strain of E. coli bacteria has been engineered to produce human insulin. GM crops could provide more food or food with an improved nutritional value such as extra vitamins.

Why this matters

Humans have been farming for around 12 000 years, but the scale, speed and technology have changed enormously in the last century. Selective breeding produced cattle that grow faster and crops that yield more grain. Industrial fertilisers, pesticides and machinery pushed yields higher still — but at a cost in soil quality, biodiversity and fossil fuel use. Meanwhile the global population keeps climbing and richer diets demand more meat, which is biologically expensive: every trophic level loses about 90% of its biomass to respiration, faeces, movement and parts not eaten. So a hectare of wheat can feed roughly ten times as many people as the same hectare used to graze cattle. Modern food production has to balance four pressures simultaneously: feeding more people, doing it sustainably (so the land, oceans and climate survive), respecting animal welfare, and keeping food affordable. Biotechnology — fermenters growing fungal protein, GM crops with engineered traits, GM bacteria producing insulin and other proteins — offers some of the most promising tools, alongside smarter farming and stricter fisheries management.

How to learn this topic

Build on what you already know

GCSE 4.4.2: aerobic respiration releases energy from glucose; some energy is always lost as heat.
GCSE 4.7.2: trophic levels, food chains, biomass losses at each level (respiration, faeces, parts not eaten).
GCSE 4.6.2: selective breeding and genetic engineering — choosing genes and transferring them between organisms.
GCSE 4.6.3: genetic engineering of bacteria to produce human insulin (cross-reference).
KS3: photosynthesis as the source of all food biomass; ideas about sustainability.

Define food security and list the threats to it (population, diet, pests, climate, costs, conflict).
Recall biomass losses up trophic levels — set up why eating producers is efficient.
Intensive farming: restricting movement and controlling temperature to channel biomass into meat.
Ethical issues with intensive farming — animal welfare.
Fisheries: declining stocks, quotas, mesh sizes — protecting young fish so they breed.
Mycoprotein from Fusarium — fermenter inputs, advantages, vegetarian protein source.
GM crops — drought resistance, pest resistance, higher yield, Golden Rice (vitamin A).
Cross-reference GM bacteria producing insulin (4.6.3).
Compare plant-based vs meat-based diets in terms of land use and biomass efficiency.
Weigh sustainability — environmental, ethical and economic trade-offs.

Key terms

food security: Having enough safe, nutritious food to feed a population reliably and sustainably. (AQA marking phrase: 'enough food to feed a population'. Mention reliability/sustainability for higher tier.)
intensive farming: Farming methods that maximise yield from a given area by restricting animal movement, controlling temperature and using high-energy feeds. (Examiners want both: 'restrict movement' AND 'control temperature' to reduce energy lost in respiration/heat.)
fishing quota: A legal limit on the mass or number of fish that can be caught from a particular stock in a given period, used to prevent over-fishing. (Marking phrase: 'fishing quotas limit how many fish are caught' — keeps stocks at a sustainable level.)
mesh size: The size of the holes in a fishing net. Larger mesh sizes allow young (small) fish to escape, so they survive to breed. (Marking phrase: 'larger mesh size lets small fish escape' — 'young fish survive to breed'.)
mycoprotein: A protein-rich food made from the fungus Fusarium grown in a fermenter on glucose syrup under aerobic conditions; sold as Quorn. (Marking phrases: 'grown in fermentation vats', 'Fusarium grows quickly', 'less land needed', 'high in protein'.)
Fusarium: A fungus used industrially to produce mycoprotein. It grows quickly when supplied with glucose, nitrogen, minerals and oxygen.
fermenter: A large stirred tank in which microorganisms (such as Fusarium or genetically modified bacteria) are grown under controlled conditions of temperature, pH and oxygen. (Often called a 'fermentation vat' in AQA mark schemes. Note 'sterile' and 'aerobic' for higher marks.)
GM crop: A crop plant that has had a gene from another organism inserted into its DNA to give it a useful trait such as drought resistance, pest resistance, higher yield or improved nutrition. (Examples to memorise: drought-resistant, pest-resistant, higher yield, Golden Rice (vitamin A).)
Golden Rice: A GM rice variety engineered to make beta-carotene (a precursor of vitamin A) in the grain, intended to prevent vitamin-A deficiency in regions where rice is the main staple. (Useful example of GM crops with improved nutritional value.)
sustainability: Meeting food and resource needs today without preventing future generations from doing the same — usually requires protecting land, water, biodiversity and fish stocks. (Marking phrase: 'maintained at a sustainable level' — applies to fisheries and farming alike.)

Notes

What is food security?

Food security is having enough food to feed a population. A country (or the world) is food-secure when its people have reliable, sustainable access to enough safe, nutritious food. Globally we currently produce enough calories to feed everyone — but the distribution is uneven, and several biological and social factors are putting that security under pressure.

### Threats to food security

Rising human population — more mouths to feed every year, with most growth in low-income countries.
Changing diets in developed nations — wealthier people eat more meat, dairy and out-of-season produce, which means scarce resources are shipped across the world.
New pests and pathogens — emerging crop diseases (like wheat rust) and livestock diseases threaten yields, often spreading faster as the climate shifts.
Environmental change — drought, flooding, heatwaves and unseasonal frosts wipe out harvests; widespread famine can follow if rainfall fails.
Cost of agricultural inputs — fertilisers, pesticides and fuel are expensive, and price spikes (often linked to fossil-fuel costs) push smaller farms out of business.
Conflict and transport disruption — war and political instability cut off water, destroy farmland and block the movement of food.

The biological response has three main strands: make existing farming more efficient, manage natural stocks (especially fisheries) sustainably, and use biotechnology to grow new sources of food.

Why eating producers is efficient

Recall from trophic levels: at every step in a food chain about 90% of biomass is lost. Energy leaves through respiration (mostly as heat), faeces (undigested material), urine and parts not eaten. Only around 10% of the biomass at one level is converted into biomass at the next.

That fact has a huge consequence for food production. Compare two diets fed by the same hectare of land:

Crops → cattle → humans (meat-based): 10 000 kg of crop biomass → ~1 000 kg of cattle → ~100 kg of human biomass.
Crops → humans (plant-based): 10 000 kg of crop biomass → ~1 000 kg of human biomass.

So a plant-based diet supports roughly ten times as many people per hectare. The AQA marking phrases for this are: 'biomass is lost between trophic levels', 'lost through respiration', 'less biomass available at higher trophic levels', and 'eating plants / producers means more biomass is available for humans'.

Intensive farming — channelling biomass into meat

When animals are kept for food, every unit of energy they spend on movement or keeping warm is energy not turned into meat or milk. Intensive (factory) farming works by limiting those losses:

Restricting movement — animals are kept in small enclosures so they expend less energy on walking around. More of the food they eat becomes their own biomass.
Controlling temperature — sheds are heated, so cattle and chickens don't burn extra glucose in respiration just to keep warm.
High-protein feeds — feeding animals concentrated protein speeds growth so they reach slaughter weight more quickly.

This raises efficiency, but the ethical objections are serious: confining animals in tight spaces causes stress and disease, behavioural needs (grazing, dust-bathing) are unmet, antibiotics are used heavily, and many people see it as cruel. The trade-off — more affordable meat versus animal welfare — is examinable.

Sustainable fisheries

Fish are a vital protein source, but stocks of many wild species (cod, tuna, herring) are declining because they are caught faster than they can reproduce. If too many adults of breeding age are removed, the population cannot recover — and entire fisheries can collapse. Two main tools are used to keep fishing sustainable:

Fishing quotas — international agreements limit how many fish (in tonnes) can be caught from a particular stock per year. Quotas prevent over-fishing and let populations recover.
Net mesh size — regulations specify a minimum mesh size for nets. Larger mesh sizes let small fish escape, so young fish survive to breed before they could be caught. Small-mesh nets catch fish too young to reproduce, which is why they're restricted.

The AQA marking phrases here are: 'fishing quotas limit how many fish are caught', 'larger mesh size lets small fish escape', 'young fish survive to breed', and 'fish stocks are maintained at a sustainable level'.

Mycoprotein from Fusarium

Mycoprotein is a protein-rich food made from the fungus Fusarium venenatum. It's the basis of Quorn, sold as a meat substitute.

The production process uses a large stirred tank called a fermenter:

Fusarium is added as a starter culture.
Glucose syrup is supplied as the carbon and energy source.
Nitrogen and mineral ions are added so the fungus can build proteins.
Sterile air (oxygen) is bubbled through — Fusarium respires aerobically.
Temperature (~30 °C) and pH are controlled by a cooling jacket and pH probes.
The fungus grows rapidly, with hyphae multiplying to fill the vat.
The biomass is harvested, filtered, purified and processed into food.

Advantages for food security (AQA marking phrases): 'grown in fermentation vats', 'high in protein', 'less land needed', 'Fusarium grows quickly'. Mycoprotein is also low in fat, suitable for vegetarians, and independent of weather or season — fermenters run all year.

Genetically modified (GM) crops

GM crops have had genes inserted from other organisms to give them useful traits. For food security the relevant traits include:

Drought resistance — crops that survive low rainfall, vital as climate changes.
Pest resistance — crops that produce their own insect-killing protein (e.g. Bt corn) reduce the need for chemical pesticides.
Higher yield — more grain per hectare from the same inputs.
Improved nutritional value — Golden Rice has been engineered to make beta-carotene (a precursor of vitamin A), helping prevent childhood blindness in regions where rice is the staple.

AQA marking phrases: 'drought-resistant', 'pest-resistant', 'higher yield', 'more food available for the population'. Concerns include possible effects on wild ecosystems, monopolies by seed companies, and worries about long-term safety — though no harm has been shown in regulated commercial GM foods to date.

GM bacteria for medicine (cross-reference)

Though properly covered in 4.6.3, the spec lets you reference this: E. coli has been genetically engineered to produce human insulin. The human insulin gene is inserted into the bacterial DNA; the bacteria are grown in fermenters and express insulin, which is purified for diabetics. The same fermenter technology used for mycoprotein is used here — and it's an example of how biotechnology can solve problems beyond just food.

Sustainability and trade-offs

No single solution will feed the future. Intensive farming raises yields but raises welfare and antibiotic-resistance concerns. Fishing quotas slow income now to protect stocks later. Mycoprotein is land-efficient but needs glucose syrup (from crops) and energy to run fermenters. GM crops can lift yields and nutrition but raise questions about ecosystem effects and corporate control of seed.

The big picture: producing food sustainably means balancing biological efficiency (getting more food from less land, water and energy), ethics (animal welfare, fairness), and environmental cost (biodiversity, fossil-fuel use, soil quality). Shifting diets towards producers, managing wild stocks, and applying biotechnology carefully are the three biological levers — and they all appear regularly on AQA papers.

Exam tips

Learn the six threats to food security as a list: population, diet change, pests/pathogens, environmental change, input costs, conflict. Pick any 2-3 for a typical 'suggest threats' question.
For intensive farming questions, give BOTH techniques: 'restrict movement' AND 'control temperature'. Each on its own is half a mark.
When answering on fisheries always pair the two tools: QUOTAS (limit how many fish are caught) and LARGER MESH SIZE (lets young fish escape). Then finish with 'young fish survive to breed' and 'stocks maintained at a sustainable level'.
For mycoprotein the four phrase points are: 'grown in fermentation vats', 'Fusarium grows quickly', 'high in protein', 'less land needed'. Memorise them in that order.
GM crops: pick from drought-resistant, pest-resistant, higher yield, improved nutrition (Golden Rice / vitamin A). 'More food available for the population' is the food-security link mark.
Don't muddle the two biotechnology examples — bacteria (E. coli) → insulin, fungus (Fusarium) → mycoprotein. Different organism, different product, both grown in fermenters.
Ethical-objection questions: name an animal welfare concern (movement restriction, stress, antibiotic use) AND acknowledge the benefit (cheaper food / more food / efficient land use). Two-sided answers score best.

Mark-scheme phrasing

Common misconceptions

Worked example

Question:

Answer:

Frequently asked questions

What is the difference between food security and food sustainability?

FOOD SECURITY is about having ENOUGH food to feed a population reliably — the right amount, at the right time, in the right places. FOOD SUSTAINABILITY is about HOW we produce it: can we keep going long-term without exhausting soil, water, fish stocks or biodiversity? You can have short-term security by over-fishing or over-using fertiliser, but you wreck the system for the future — so the two ideas have to go together. AQA expects you to mention both 'enough food for the population' AND 'maintained at a sustainable level' when answering questions about future food production.

Why does eating less meat help feed more people?

Because about 90% of biomass is lost at every step in a food chain — through respiration (mostly as heat), faeces, urine and parts not eaten. So if you grow 10 000 kg of cereal and feed it to cattle, you only get around 1 000 kg of beef, and that beef only contributes about 100 kg of human biomass. If you feed the cereal directly to people, you skip the cattle step and roughly 1 000 kg of human biomass is supported — about ten times as much. A more plant-based diet means a hectare of farmland can feed many more people. The mark-scheme phrases are 'biomass is lost between trophic levels', 'less biomass available at higher trophic levels' and 'eating plants / producers means more biomass is available for humans'.

How exactly is mycoprotein different from meat?

Mycoprotein is made from a FUNGUS (Fusarium), not an animal. The fungus is grown in a fermentation vat on glucose syrup, with sterile oxygen, nitrogen and mineral ions. After a few days the fungus has multiplied enormously and the biomass is filtered out, purified, mixed with binders and flavourings and shaped into food (sold as Quorn). It is high in protein, low in fat, contains fibre and has no cholesterol. The advantages for food security are that Fusarium grows quickly, less land is needed than for raising cattle or growing soya, and production is independent of weather and season — a fermenter works all year round.

What's the point of larger fishing-net mesh sizes?

Larger mesh sizes have bigger holes, so SMALL young fish slip through and escape. Only larger adult fish are caught. Because the young survive, they can grow up and breed, producing the next generation — and the stock keeps replenishing. If you used a small mesh you'd catch everything, including young fish that hadn't yet bred, and the population would collapse. Combined with fishing quotas (limits on the total mass of fish that can be caught) this is the main way fisheries are kept at a sustainable level. AQA marking phrases: 'larger mesh size lets small fish escape', 'young fish survive to breed', 'fish stocks are maintained at a sustainable level'.

Are GM crops safe to eat?

Yes — every regulated commercial GM crop has been through extensive safety testing, and there is no evidence that the food itself causes harm to people. All foods contain DNA, and the digestive system breaks DNA down whether it comes from a GM or non-GM plant. The serious debates about GM are mostly about ENVIRONMENTAL effects (could engineered genes spread to wild plants? would pest-resistant crops harm non-target insects?) and ECONOMIC ones (large seed companies controlling food supply, farmers unable to save seed). For exam purposes you should weigh the benefits — drought-resistant, pest-resistant, higher yield, improved nutrition such as Golden Rice — against these ecological and economic concerns.

Why is intensive farming controversial?

Intensive farming makes meat production more efficient by restricting animal movement (less energy 'wasted' on activity) and controlling temperature (less energy used to keep warm), so more of the food fed to animals becomes their biomass. But the ethical and practical objections are strong: confining animals causes stress and reduces welfare; disease spreads more easily in crowded conditions and antibiotics are often used routinely, contributing to antibiotic resistance; and many people simply find the conditions cruel. The trade-off — cheaper, more plentiful meat versus animal welfare and antibiotic concerns — is examinable, and a good answer mentions both sides.