Factors affecting food security & Farming techniques (both biology only)

Lesson 7.12 · AQA 8461

Factors Affecting Food Security & Farming Techniques

Spec 4.7.5.1, 4.7.5.2 · Paper 2 · ~10 min

Biology only

What you'll be able to do

By the end of this lesson, you'll be able to:

Objective 1 4.7.5.1

Describe the six biological factors that threaten food security, using the spec list.

Objective 2 4.7.5.2

Explain how restricting movement and controlling temperature improve the efficiency of food production.

Objective 3 WS 1.3 / 1.4

Evaluate the advantages and disadvantages of intensive farming, including ethical objections.

What food security means

Spec definition

Food security is having enough food to feed a population.

Globally, food security is under pressure. The world population is rising — currently around 8 billion and projected to reach roughly 9–10 billion by 2050. At the same time, the amount of land available for farming is not growing.

The spec's headline message

"Sustainable methods must be found to feed all people on Earth." This is the framing for the rest of the lesson — six factors put food security at risk; spec-named farming techniques attempt to maximise efficiency within those constraints.

Six factors threatening food security

The spec lists six biological factors exactly. Learn them — they're the foundation of every food-security question.

1Increasing birth rate Has threatened food security in some countries — more people to feed from the same land.

2Changing diets In developed countries, changing diets mean scarce food resources are transported around the world.

3New pests & pathogens That affect farming — emerging diseases and invasive pests can devastate crops and livestock.

4Environmental changes That affect food production — for example, widespread famine occurs in some countries if the rains fail.

5Cost of agricultural inputs Fuel, fertilisers, machinery and pesticides all cost money. Farmers in poorer regions can't afford them.

6Conflicts In some parts of the world — affecting the availability of water or food.

Exam phrasing

"Describe biological factors affecting food security" or "Suggest two factors threatening food security" — pick from this spec list. Use the spec phrasing.

Why farming efficiency matters

Recall the 10% rule from Lesson 7.11 — only ~10% of biomass transfers between trophic levels. When we farm animals for meat, eggs or milk, that 90% loss is a direct cost.

The food-chain economics

1 hectare growing wheat for humans (Level 1 → Level 2) can feed many people. The same hectare growing wheat to feed cattle (Level 1 → Level 2 → Level 3) feeds far fewer — most of the wheat biomass never makes it into human food.

Spec language

"The efficiency of food production can be improved by restricting energy transfer from food animals to the environment." If we can stop animals from losing biomass to respiration and heat, more becomes meat. The next two slides cover the spec's two named methods.

Cross-module link

This connects directly to Module 4 respiration: when animals respire, they release CO₂, water, and heat — all energy lost to the environment. Cutting respiration = cutting losses.

Technique 1 — Limiting movement

Movement requires energy. Energy comes from respiring glucose. Respiring glucose releases CO₂ and water — biomass lost to the environment.

PEE-style mechanism

Point: Movement uses energy from respiration. Evidence: Respiration converts glucose into CO₂ and water — biomass that's lost. Explain: If animals are kept in small enclosures, they move less, respire less, and more of the glucose from their food goes into building body mass — meat, eggs or milk — instead of being lost to the environment.

Technique 2 — Controlling temperature

Mammals and birds are endotherms — they maintain a constant body temperature. In cold environments, that takes energy.

Spec mechanism

The spec says efficiency improves by "controlling the temperature of their surroundings." If the environment is kept warm, the animal doesn't need to respire as much to generate body heat.

PEE-style explanation

Point: Keeping warm uses energy. Evidence: Heat is generated by respiration; in cold conditions, more glucose must be respired to maintain body temperature. Explain: Heating an animal's surroundings reduces this demand, so less biomass is lost to respiration and more is converted into growth.

Real-world examples

Heated sheds for poultry, indoor pig units with controlled temperature, calf rearing pens. All apply the same principle: warm surroundings → less respiratory loss → faster growth on less feed.

Additional — High-protein feed

The spec adds a brief third method.

Spec wording

"Some animals are fed high protein foods to increase growth."

Why protein speeds growth

Protein in the diet is broken down to amino acids, which the animal uses to build new proteins for muscle and tissue growth. A diet richer in protein than the animal would get naturally directly supplies the building blocks for biomass. (Module 2 cross-link — digestive enzymes and amino acid absorption.)

Combined effect

Intensive farming usually combines all three: restricted movement + controlled temperature + high-protein feed. That's why factory-farmed chickens reach slaughter weight in 5–7 weeks vs the months a free-range bird takes.

Intensive vs free-range — the trade-offs

Both approaches feed people. They differ in how much, at what cost, and at what ethical price.

Operational definition

Intensive farming = the combination of restricted movement + controlled (warm) temperature + high-protein feed. The spec (WS 1.3) refers to this as "modern intensive farming methods."

Intensive farming

Advantages

More food produced per hectare

Cheaper food for consumers

Faster animal growth

Easier disease monitoring (controlled conditions)

Disadvantages(MS-credit-worthy phrasings)

Increased disease spread from crowding

Heavier antibiotic use → resistance; antibiotics in meat/milk

Extra cost of heating, lighting, food and drugs

Stress causes aggressive behaviour / reduces productivity

Free-range / extensive

Advantages

Better animal welfare

Lower antibiotic use

Lower disease risk from crowding

Often viewed as more "natural"

Disadvantages

Less food produced per hectare

More expensive for consumers

Slower animal growth

Larger land use

Ethical objections to intensive farming

The spec explicitly notes (WS 1.3) that "some people have ethical objections to some modern intensive farming methods." Exam questions on this topic test your ability to name and explain these objections.

StressStress and aggressive behaviour. Crowded, confined conditions cause stress, which can lead to aggressive behaviour (causing harm to other animals) and reduce productivity. AQA mark schemes credit this — "aggressive behaviour" is on the MS list; "cruelty" alone is not.

DiseaseCrowding spreads infection. Many animals in close contact lets pathogens move quickly through the herd or flock. This is a public-health concern as well as a welfare one.

AntibioticsHeavy antibiotic use. Routine antibiotic use is needed to prevent disease in crowded conditions — but this drives antibiotic resistance, which threatens human medicine (Module 6 link).

EnvironmentConcentrated waste. Slurry pits from thousands of animals can pollute rivers and groundwater. Heating sheds also consumes fossil fuels.

Name food security factors

Food security is the ability of a population to access enough food.

Give three biological factors that may threaten food security. 3 marks

Any three from the spec list:

1

Increasing birth rate. (1)

2

Changing diets in developed countries (scarce resources transported globally). (1)

3

New pests and pathogens affecting farming. (1)

4

Environmental changes affecting food production (e.g. famine if rains fail). (1)

5

Cost of agricultural inputs. (1)

6

Conflicts affecting availability of water or food. (1)

Use the spec phrasing. "More people" is too vague — say "increasing birth rate". "Bad weather" is too vague — say "environmental changes" or "rains fail." Spec wording gets the marks.

Explain intensive farming efficiency

Some farmers keep their pigs indoors in small heated pens rather than letting them roam outdoors.

Explain how this intensive method improves the efficiency of food production. 4 marks

1

Movement requires energy from respiration of glucose. Respiration releases CO₂ and water — biomass that is lost to the environment. (1)

2

Restricting movement (small pens) means the pigs respire less for movement, so less biomass is lost. (1)

3

Keeping the surroundings warm means the pigs respire less to maintain body temperature (less heat needs to be generated). (1)

4

Both effects mean more of the glucose from food is used for growth — more meat produced per kg of feed, so production is more efficient. (1)

4-mark "explain intensive farming" questions (Specimen P2 Q8.2 pattern) want both mechanisms — movement and temperature. Each mechanism needs the link to respiration. "Pigs grow bigger" without naming respiration scores zero.

Evaluate intensive farming

A pig farmer is deciding whether to switch to intensive indoor methods (small pens, heated sheds, high-protein feed).

Evaluate the advantages and disadvantages of intensive farming methods. 4 marks

Pattern 13 evaluation — score at least one advantage + one disadvantage, plus reasoning, plus a conclusion.

A1

Advantage: More food produced per hectare — restricted movement and warm sheds reduce respiratory losses, so more biomass is converted to growth. (1)

A2

Advantage: Cheaper food for consumers / shorter time to slaughter weight. (1)

D1

Disadvantage: Crowding increases the spread of disease, requiring routine antibiotic use — driving antibiotic resistance (Module 6 link). (1)

D2

Disadvantage: Extra cost of heating, lighting, food and drugs. Stressful conditions can cause aggressive behaviour, reducing productivity. (1)

Pattern 13 (Evaluate) demands both sides. Listing only advantages or only disadvantages caps at half marks. Critical: AQA mark schemes (e.g. Jun 2022 P2 Q6.6) explicitly ignore "cruelty" / "unethical" / "religion" as disadvantages — credit goes to concrete mechanisms (disease spread, antibiotic use, heating costs, stress-induced aggression). End with a justified conclusion ("depends on whether the farmer prioritises cost or welfare").

Examiner alerts

Alert 1 — Use spec phrasing for the six factors

"Increasing birth rate" not "more people". "Environmental changes" not "weather". "Cost of agricultural inputs" not "things cost too much". Mark schemes credit spec wording.

Alert 2 — Name the mechanism, not just the outcome

"Chickens grow faster" doesn't explain why. The marks are for movement → respiration → biomass loss. Always trace the biology.

Alert 3 — Evaluate means both sides

For Pattern 13 evaluation questions (advantages and disadvantages), one-sided answers cap at half marks. Give an advantage and a disadvantage, then a conclusion.

Alert 4 — Read the stem: "other" disadvantages

If the question stem says "some people think the methods are unethical — suggest two other disadvantages" (a real Specimen P2 Q8 framing), you must give non-welfare answers. Mark schemes also ignore "cruelty" / "unethical" / "religion" in many MS lists (e.g. Jun 2022 P2 Q6.6). Lead with concrete mechanisms: disease spread, antibiotic resistance, heating costs, stress-induced aggression.

Common errors — fix these now

✗ Weak

"There are too many people."Vague — not a spec factor.

✓ Strong

"The increasing birth rate has threatened food security in some countries."Spec wording verbatim.

✗ Weak

"Restricting movement makes chickens grow faster."No mechanism named.

✓ Strong

"Less movement means less respiration, so more biomass is converted to growth instead of being lost as CO₂ and water."Mechanism via respiration.

✗ Weak

"Intensive farming is bad."One-sided; no evaluation.

✓ Strong

"Intensive farming produces more food per hectare, but raises welfare and antibiotic-resistance concerns."Balanced evaluation — both sides.

Recap — three things to remember

1

Food security and its six threats

Food security = having enough food to feed a population. Six spec factors threaten it: increasing birth rate · changing diets · new pests & pathogens · environmental changes · cost of agricultural inputs · conflicts.

2

Two spec-named efficiency techniques (plus a third)

"The efficiency of food production can be improved by restricting energy transfer from food animals to the environment" — by limiting movement and controlling the temperature of their surroundings. Also: high-protein foods to increase growth.

3

Evaluation has two sides

Intensive farming = more food, cheaper food, faster growth. But also welfare concerns, antibiotic resistance, concentrated waste. The exam wants both sides plus a justified conclusion.

Next lesson

7.13 — Sustainable fisheries & the role of biotechnology. Both Biology only. We'll cover fishing quotas, net mesh size, mycoprotein from Fusarium, and GM crops.