What are the main factors affecting food supply in ecosystems?

The main factors affecting food supply in ecosystems include climate change, soil quality, water availability, and human activities such as deforestation and pollution. These factors can influence the growth of crops and the availability of food resources, impacting the overall food supply.

How does human population growth impact food supply?

Human population growth increases the demand for food, which can strain existing resources and lead to overexploitation of agricultural land. This can result in habitat destruction, loss of biodiversity, and increased pressure on food production systems to meet the growing needs.

What role does technology play in improving food supply?

Technology plays a crucial role in improving food supply by enhancing agricultural productivity through innovations such as genetically modified organisms (GMOs), precision farming, and sustainable farming practices. These technologies can increase crop yields, reduce waste, and improve the efficiency of food production.

How does climate change affect food supply in ecosystems?

Climate change affects food supply by altering weather patterns, leading to extreme conditions such as droughts and floods. These changes can disrupt crop growth cycles, reduce yields, and affect the availability of water resources, making it challenging to maintain a stable food supply.

What sustainable practices can help ensure a stable food supply?

Sustainable practices that can help ensure a stable food supply include crop rotation, organic farming, agroforestry, and the use of renewable energy sources. These practices aim to maintain soil health, conserve water, and reduce the environmental impact of agriculture, contributing to a more resilient food production system.

Why is "Saying pesticides only help." a common mistake in Food Supply?

Why it happens: Their purpose. How to avoid it: Pesticides also kill BENEFICIAL insects (bees, predators of pests). Persistent pesticides bioaccumulate in food chains. Trade-off.

Why is "Saying fertilisers DIRECTLY kill fish." a common mistake in Food Supply?

Why it happens: Both involve water + chemicals. How to avoid it: Fertilisers don't kill fish directly. They cause algae to bloom → die → decompose → O₂ depletion → fish suffocate. Indirect chain of events.

Human Influences on EcosystemsCambridge IGCSE Biology (0610)

Food Supply

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

PreviousNext

Learn this Topic

Start with the slides for the quick version, then go deeper with the full study notes.

Short Study Notes in the form of Slides

Read the notes first. If the method in a worked example clicks, you're ready for the questions.

Page 1 / 0

Detailed Study Notes

Full prose, callouts and a recap — built for A* mastery, not just a quick scan.

Take these study notes with you

Download a branded PDF — full prose, callouts, recap and memorise list for Food Supply, ready to print or save offline.

Food Supply — Cambridge IGCSE 0610 Biology Extended (2026)

Modern farming feeds billions but has costs. Cambridge wants the methods, the trade-offs, and EUTROPHICATION in detail.

What you’ll learn

Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).

20.1 — Describe modern agricultural methods.
20.1 — State advantages and disadvantages.
20.1 — Describe eutrophication.

Modern agricultural methods

Five big tools: fertilisers, pesticides, monoculture, intensive farming, breeding.

1. Fertilisers.

Add NITRATE, PHOSPHATE, POTASSIUM to soil.
Replace nutrients lost to harvested crops.
Result: faster, healthier growth → higher yields.
Risk: runoff → eutrophication.

2. Pesticides + herbicides.

Pesticides KILL crop-damaging organisms (insects, fungi, rodents).
Herbicides kill WEEDS that compete with crops.
Result: less crop loss → higher yields.
Risk: kill beneficial insects (bees, ladybirds), build up in food chains, evolve pesticide resistance.

3. Monoculture.

Plant ONE crop (e.g. wheat) across vast areas.
Easy to plant, manage, harvest with machines.
Result: economies of scale → cheap food.
Risk: vulnerable to pests/disease (no diversity), reduces biodiversity, depletes specific soil nutrients.

4. Intensive (factory) farming.

Many animals in small spaces.
Feed controlled, growth optimised, antibiotics used.
Result: more meat/dairy/eggs per area.
Risk: animal welfare concerns, antibiotic resistance, disease spread.

5. Selective breeding.

High-yield varieties (e.g. modern wheat, dairy cows).
Disease-resistant varieties.
Result: ongoing yield improvements.
Risk: reduced genetic diversity → vulnerable to new diseases.

Other:

GREENHOUSES: control conditions year-round.
IRRIGATION: bring water to dry areas.
GENETIC MODIFICATION (GM): direct DNA changes.

Worked qualitative. Why does WHEAT grown today yield 4-5× more per hectare than wheat from 1900?

Selective breeding for high-yield varieties.
Better fertilisers + pesticides.
Better farming techniques and machinery.
Genetics + agriculture together.

Cambridge tip. When asked how to increase food supply, give 4-5 methods with their effect. Cambridge marks both.

Fertilisers: more growth.
Pesticides: less crop loss.
Monoculture: easy management.
Intensive: more output per area.
Trade-offs at every step.

Eutrophication — fertilisers polluting waterways

The chain of events that turns rivers into dead zones.

The chain (memorise):

Excess FERTILISER washes off fields → into LAKES, RIVERS, COASTAL WATERS.
Extra NITRATES + PHOSPHATES in water → ALGAE BLOOM (and other water plants).
Algae cover the surface → BLOCK SUNLIGHT → underwater plants can't photosynthesise → die.
Algae also die naturally (short-lived).
BACTERIA decompose dead algae + plants → use up DISSOLVED OXYGEN in water (aerobic respiration).
Low O₂ in water → fish, insects, other aquatic animals SUFFOCATE → die.
Lake becomes a 'dead zone' — almost lifeless except for anaerobic bacteria.

Where it happens:

Lake Erie (North America), Baltic Sea, Gulf of Mexico ('Dead Zone' from Mississippi runoff).
Many smaller lakes worldwide.

Reducing eutrophication:

Use less fertiliser; apply at right time (when plants will absorb).
Buffer strips of plants between fields and waterways (catch runoff).
Cover crops in fall to absorb leftover nutrients.
Constructed wetlands to filter farm runoff.

Worked qualitative. Why does sewage discharge ALSO cause eutrophication?

Sewage contains nitrates + phosphates (from urine + detergents).
Same effect as fertiliser runoff.
Why sewage treatment plants must REMOVE nutrients before discharge.

Cambridge tip. Memorise the chain. Cambridge often asks for it word-for-word. Keywords: ALGAE BLOOM, BLOCK LIGHT, BACTERIA DECOMPOSE, OXYGEN DEPLETED, FISH DIE.

Fertiliser runs off → waterways.
Algae bloom → block light.
Plants die.
Bacteria decompose → O₂ used.
Fish suffocate; dead zone.

Trade-offs and sustainable alternatives

Modern agriculture feeds billions but isn't sustainable as-is. Alternatives exist.

The core dilemma.

Need to feed ~8 billion people (and growing).
Modern farming has costs: pollution, biodiversity loss, climate impacts.
Need to balance YIELD with SUSTAINABILITY.

Sustainable alternatives:

1. Crop rotation.

Different crops in different years on same land.
Includes LEGUMES (nitrogen-fixing) → reduce need for fertiliser.
Different crops have different nutrient needs and pest profiles.

2. Biological pest control.

Use natural predators of pests instead of pesticides.
Example: ladybirds eat aphids; certain wasps parasitise caterpillars.
Reduces chemical use.

3. Integrated pest management (IPM).

Combine multiple methods: biological, monitoring, targeted pesticide use.
Apply pesticide only when pests exceed threshold.
Less chemical input overall.

4. Organic farming.

No synthetic fertilisers or pesticides.
Natural composts, manures, biological control.
Lower yield but more sustainable; specific markets.

5. Genetic modification.

Drought-resistant crops, pest-resistant crops.
Reduce need for irrigation and pesticides.
Controversial; benefits vs risks debated.

Worked qualitative. Why might INSECT POPULATIONS be CRASHING globally?

Pesticide use kills insects directly.
Habitat loss (monoculture, urbanisation).
Climate change shifts conditions.
Light pollution disorients night-flying insects.
~75% decline in flying insect biomass in some studies.
Knock-on effects: fewer pollinators → crop yields threatened; fewer prey → birds and other wildlife decline.

Cambridge tip. When asked sustainable alternatives, give 3-4. Cambridge marks each.

Need: feed billions sustainably.
Crop rotation, biological control.
IPM combines methods.
Organic + GM trade-offs.
Insect decline = global concern.

How it’s examined

Food supply appears Paper 4 (5-7 marks: methods, eutrophication chain). Examiner reports flag students missing eutrophication steps (algae bloom → block light → bacteria → O₂ depletion).

Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (20.1); 0610/22 May/Jun 2024 — Q13 (food supply); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Food Supply, ready to print or save as PDF.

Step-by-step worked examples — Food Supply

Step-by-step solutions to past-paper-style questions on food supply, written exactly the way a tutor would explain them at the board.

1Modern agricultural methods
Core• agriculture
Question
Describe FOUR methods used in modern agriculture to increase food supply.
Step-by-step solution
1. Step 1
  FERTILISERS: nitrate, phosphate, potassium → faster plant growth, higher yields.
2. Step 2
  PESTICIDES + HERBICIDES: kill pests/weeds → reduce crop loss.
3. Step 3
  MONOCULTURE: planting one crop over a large area → efficient harvesting/management.
4. Step 4
  INTENSIVE FARMING: high stocking density of animals (factory farming) → more meat/dairy per hectare.
5. Step 5
  Plus: SELECTIVE BREEDING (high-yield varieties), GREENHOUSES, IRRIGATION, GM crops.
Answer
Fertilisers, pesticides/herbicides, monoculture, intensive (factory) farming, selective breeding, greenhouses, GM crops.
2Fertilisers — pros and cons
Extended• Adapted from 0610/22 May/Jun 2024 Q13• fertilisers
Question
Give TWO advantages and TWO disadvantages of using nitrate fertilisers.
Step-by-step solution
1. Step 1
  Advantages:
2. Step 2
  Faster plant growth → higher yields → more food.
3. Step 3
  Replaces nitrogen lost to harvested crops → maintains soil fertility.
4. Step 4
  Disadvantages:
5. Step 5
  EUTROPHICATION: excess fertiliser washes into rivers/lakes → algae bloom → algae die → bacteria decompose → use up O₂ → fish die.
6. Step 6
  Expensive; requires energy to produce; risk of contamination of drinking water.
Answer
Pros: more growth, higher yield, replenishes soil. Cons: eutrophication of waterways, expensive, contamination.
3Eutrophication — the chain of events
Extended• eutrophication
Question
Describe the steps of EUTROPHICATION caused by fertiliser runoff.
Step-by-step solution
1. Step 1
  Excess fertiliser washes into a lake/river.
2. Step 2
  Extra NITRATES + PHOSPHATES → algae and other plants bloom (rapid growth).
3. Step 3
  Algae block light → underwater plants die.
4. Step 4
  Algae die → bacteria DECOMPOSE them → use up O₂ from water.
5. Step 5
  Low O₂ → fish + other aquatic animals die.
6. Step 6
  Lake becomes lifeless 'dead zone'.
Answer
Fertiliser → algae bloom → block light → plants die → bacteria decompose → O₂ depleted → fish die.

Key Definitions and Keywords — Food Supply

Definitions to memorise and the exact keywords mark schemes credit for food supply answers — sharpened from recent examiner reports for the 2026 0610 sitting.

Monoculture
Examiner keyword
Growing a single crop over a large area. Efficient but reduces biodiversity and increases disease risk.
Fertiliser
Substance added to soil to increase plant growth. Usually contains nitrate, phosphate, potassium.
Pesticide
Chemical that kills pests (insects, fungi, weeds). Increases crop yields but can harm non-target species.
Eutrophication
Examiner keyword
Process where nutrient runoff (e.g. fertiliser nitrates) causes algal blooms in water → leads to oxygen depletion and death of fish.
Intensive farming
Farming with high inputs (fertilisers, pesticides, machinery, dense livestock) for maximum output per land area.

Common Mistakes and Misconceptions — Food Supply

The traps other students keep falling into on food supply questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.

✕Saying pesticides only help.
Why it happens
Their purpose.
How to avoid it
Pesticides also kill BENEFICIAL insects (bees, predators of pests). Persistent pesticides bioaccumulate in food chains. Trade-off.
✕Saying fertilisers DIRECTLY kill fish.
Why it happens
Both involve water + chemicals.
How to avoid it
Fertilisers don't kill fish directly. They cause algae to bloom → die → decompose → O₂ depletion → fish suffocate. Indirect chain of events.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Food Supply — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Food Supply

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Modern agricultural methods

2Fertilisers — pros and cons

3Eutrophication — the chain of events

Monoculture

Fertiliser

Pesticide

Eutrophication

Intensive farming

✕Saying pesticides only help.

✕Saying fertilisers DIRECTLY kill fish.

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Food Supply — frequently asked questions