19.2

Food chains and food webs

Cambridge IGCSE Biology (0610)  · Unit 19: Organisms and their environment  · 10 flashcards

Food chains and food webs is topic 19.2 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 19 — Organisms and their environment , alongside Energy flow, Nutrient cycles and Populations.  In one line: A food chain illustrates the transfer of energy from one organism to the next, starting with a producer.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).

The deck below contains 10 flashcards — 8 definitions, 1 key concept and 1 application card — covering the precise wording mark schemes reward.  Use the 8 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

A food chain

A food chain illustrates the transfer of energy from one organism to the next, starting with a producer.

Example: Grass (producer) → Grasshopper (primary consumer) → Frog (secondary consumer) → Snake (tertiary consumer).

What the Cambridge 0610 syllabus says

2026-2028 syllabus, in our words

What the syllabus expects you to be able to do in this topic, in plain English. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks. For the exact wording, see the official syllabus (PDF).

  1. Describe Describe a food chain: it shows energy being transferred from organism to organism, starting with a producer.
  2. Construct Construct simple food chains and interpret them.
  3. Describe Describe a food web: a network made of linked food chains; also interpret food webs.
  4. Describe Describe a producer: an organism that produces its own organic nutrients by photosynthesis, normally using energy from sunlight.
  5. Describe Describe a consumer: an organism that gets energy from feeding on other organisms.
  6. State State that, depending on where they sit in a food chain, consumers can be grouped as primary, secondary, tertiary or quaternary.
  7. Describe Describe a herbivore: an animal that obtains its energy from eating plants.
  8. Describe Describe a carnivore: an animal that obtains its energy from eating other animals.
  9. Describe Describe a decomposer: an organism that obtains its energy from dead organic material or organic waste.
  10. Use Describe, using food webs and food chains, the effects humans have when they overharvest species used for food or bring foreign species into a habitat.
  11. Draw Draw pyramids of biomass and pyramids of numbers, then describe and interpret them.
  12. Discuss Discuss the benefits of representing a food chain with a pyramid of biomass instead of a pyramid of numbers.
  13. Describe Describe a trophic level: the position an organism occupies in an ecological pyramid, food web or food chain.
  14. Identify Identify the trophic levels in ecological pyramids, food webs and food chains: producers, then primary, secondary, tertiary and quaternary consumers.
  15. Draw Draw pyramids of energy, then describe and interpret them. Supplement
  16. Discuss Discuss the benefits of representing a food chain with a pyramid of energy instead of a pyramid of numbers or of biomass. Supplement
  17. Explain Explain why energy transfer between trophic levels is often inefficient. Supplement
  18. Explain Explain, by referring to energy losses, why food chains rarely have as many as five trophic levels. Supplement
  19. Explain Explain why humans make more efficient use of energy by eating crop plants than by eating livestock raised on crop plants. Supplement
Definition Flip

What is a food chain?

Answer Flip

A food chain illustrates the transfer of energy from one organism to the next, starting with a producer.

Example: Grass (producer) → Grasshopper (primary consumer) → Frog (secondary consumer) → Snake (tertiary consumer).
Definition Flip

What is a producer?

Answer Flip

A producer is an organism that creates its own organic nutrients, typically using sunlight through photosynthesis.

Example: Plants, algae, and some bacteria convert sunlight into glucose.
Definition Flip

What is a consumer?

Answer Flip

A consumer is an organism that obtains energy by feeding on other organisms.

Example: A lion consuming a zebra or a deer consuming grass.
Definition Flip

What are primary, secondary, tertiary, and quaternary consumers?

Answer Flip

Consumers are classified based on their position in the food chain. Primary consumers eat producers, secondary eat primary, tertiary eat secondary, and quaternary eat tertiary consumers.

Example: Grass → Grasshopper → Frog → Snake → Hawk shows primary, secondary, tertiary, and quaternary consumers respectively.
Definition Flip

Define a herbivore.

Answer Flip

A herbivore is an animal that obtains energy by consuming plants.

Example: A cow eating grass, or a caterpillar eating leaves.
Definition Flip

Define a carnivore.

Answer Flip

A carnivore is an animal that obtains energy by consuming other animals.

Example: A lion eating a zebra, or a snake eating a mouse.
Definition Flip

Define a decomposer.

Answer Flip

A decomposer is an organism that obtains energy from dead or waste organic material.

Example: Fungi and bacteria breaking down a dead log.
Key Concept Flip

How can overharvesting impact food chains?

Answer Flip

Overharvesting a food species can cause its population to collapse, impacting the consumers that rely on it and potentially disrupting the entire food web.

Example: Overfishing cod can lead to starvation of seabirds that depend on them.
Key Concept Flip

Why is a pyramid of biomass better than a pyramid of numbers?

Answer Flip

A pyramid of biomass accounts for the mass of organisms at each trophic level, providing a more accurate representation of energy flow than a pyramid of numbers, which only counts individuals. Biomass corrects for differences in size.

Example: Many aphids can feed on one tree, but the tree's biomass is far greater.
Definition Flip

Define 'trophic level'.

Answer Flip

A trophic level is the position of an organism in a food chain, food web, or ecological pyramid.

Example: Producers form the first trophic level, primary consumers the second, and so on.

Review the material

Read revision notes with definitions, equations, and exam tips.

Read Notes

Test yourself

Practice with MCQ questions to check your understanding.

Take Biology Quiz
19.1 Energy flow 19.3 Nutrient cycles

Key Questions: Food chains and food webs

What is a food chain?

A food chain illustrates the transfer of energy from one organism to the next, starting with a producer.

Example: Grass (producer) → Grasshopper (primary consumer) → Frog (secondary consumer) → Snake (tertiary consumer).
What is a producer?

A producer is an organism that creates its own organic nutrients, typically using sunlight through photosynthesis.

Example: Plants, algae, and some bacteria convert sunlight into glucose.
What is a consumer?

A consumer is an organism that obtains energy by feeding on other organisms.

Example: A lion consuming a zebra or a deer consuming grass.
What are primary, secondary, tertiary, and quaternary consumers?

Consumers are classified based on their position in the food chain. Primary consumers eat producers, secondary eat primary, tertiary eat secondary, and quaternary eat tertiary consumers.

Example: Grass → Grasshopper → Frog → Snake → Hawk shows primary, secondary, tertiary, and quaternary consumers respectively.
Define a herbivore.

A herbivore is an animal that obtains energy by consuming plants.

Example: A cow eating grass, or a caterpillar eating leaves.

More topics in Unit 19 — Organisms and their environment

Food chains and food webs sits alongside these Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

19.1 Energy flow

10 flashcards
19.3 Nutrient cycles

12 flashcards
19.4 Populations

12 flashcards

Key terms covered in this Food chains and food webs deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

Food chain
Producer
Consumer
Primary, secondary, tertiary, and quaternary consumers
A herbivore
A carnivore
A decomposer
'trophic level'

Related Biology guides

Long-read articles that go beyond the deck — cover the whole subject's common mistakes, high-yield content and revision pacing.

IGCSE Biology common mistakes

Where marks slip and how to avoid the most-common errors

IGCSE Biology high-yield questions

The 30+ definitions and processes that recur year after year

IGCSE Biology 2-week revision plan

Daily breakdown for the fortnight before exams

How to study this Food chains and food webs deck

Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.