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

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. Describe Describe a food chain as showing the transfer of energy from one organism to the next, beginning with a producer
  2. Construct Construct and interpret simple food chains
  3. Describe Describe a food web as a network of interconnected food chains and interpret food webs
  4. Describe Describe a producer as an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
  5. Describe Describe a consumer as an organism that gets its energy by feeding on other organisms
  6. State State that consumers may be classed as primary, secondary, tertiary and quaternary according to their position in a food chain
  7. Describe Describe a herbivore as an animal that gets its energy by eating plants
  8. Describe Describe a carnivore as an animal that gets its energy by eating other animals
  9. Describe Describe a decomposer as an organism that gets its energy from dead or waste organic material
  10. Use Use food chains and food webs to describe the impact humans have through overharvesting of food species and through introducing foreign species to a habitat
  11. Draw Draw, describe and interpret pyramids of numbers and pyramids of biomass
  12. Discuss Discuss the advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain
  13. Describe Describe a trophic level as the position of an organism in a food chain, food web or ecological pyramid
  14. Identify Identify the following as the trophic levels in food webs, food chains and ecological pyramids: producers, primary consumers, secondary consumers, tertiary consumers and quaternary consumers
  15. Draw Draw, describe and interpret pyramids of energy Supplement
  16. Discuss Discuss the advantages of using a pyramid of energy rather than pyramids of numbers or biomass to represent a food chain Supplement
  17. Explain Explain why the transfer of energy from one trophic level to another is often not efficient Supplement
  18. Explain Explain, in terms of energy loss, why food chains usually have fewer than five trophic levels Supplement
  19. Explain Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed 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.

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Test yourself

Practice with MCQ questions to check your understanding.

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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

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0610 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

carbon cycle nitrogen cycle water cycle decomposition respiration photosynthesis combustion fossil fuel nitrogen fixation denitrification nitrification decomposer bacteria

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'

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