Learn in your language
Skip to content
IGCSE · Cambridge (CIE) · 0653

Transfer carbon by feeding

Feeding moves carbon-containing organic molecules from a producer to consumers and between consumers.

Carbon cycle · Cambridge IGCSE Combined Science 0653 · B15.3

Cross-referenced to the 2028–2029 0653 section using original teaching from the related single-science courses. A 0653-specific objective-by-objective and Core/Supplement review is in progress. Written practice is self-checked and does not demonstrate supervised laboratory competence or award an official Cambridge grade.

Before you begin

  • Use the food-web pathway and distinguish matter cycling from energy flow.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

What is transferred by feeding in the carbon cycle?

What you will learn

  • Trace carbon through feeding links
  • Connect food-chain arrows with transfer of carbon-containing matter

Food transfers matter between organisms

When an animal feeds, it takes in organic material containing carbon. Digestion breaks large food molecules into smaller molecules that can be absorbed; some absorbed carbon becomes part of the animal’s organic material. Feeding therefore transfers carbon through food chains.

Use the chain and feeding links to trace direction. Carbon in a plant can move to a herbivore and then to a carnivore. Not every carbon atom in food becomes animal tissue; respiration, waste and uneaten material provide other routes in the cycle.

Connect carbon flow to, but distinguish it from, energy flow

The same feeding event transfers organic matter and chemical energy, but carbon and energy are not identical. Carbon atoms can be rearranged into new molecules. Energy is transferred through organisms and eventually to the environment.

In a carbon-cycle answer, name carbon-containing material and feeding. In an energy-flow answer, identify energy forms or transfers. Do not say carbon itself is a type of energy.

Sources for this lesson

Pause and explain

Which path correctly follows carbon in a food chain?

Put the idea to work

Worked example

A grasshopper eats a leaf and a frog eats the grasshopper. Trace carbon through these feeding events.

Show the worked solution
  1. The leaf contains carbon in organic molecules.
  2. Feeding transfers those molecules first to the grasshopper and then to the frog.

Answer Plant organic carbon → grasshopper organic material by feeding → frog organic material by feeding.

Try a topic test

Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.

Test this topic →

From guided practice to a new situation

Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.

1 · Guided

Trace carbon from a crop plant through a cow to a person who eats the cow.

Give me a hint

Follow each feeding link in order.

Compare my reasoning
  1. The cow eats crop plant material.
  2. The person eats cow material.

Crop-plant organic carbon → cow organic material by feeding → human organic material by feeding.

Look for these in your work

  • Both links in order
  • Carbon-containing matter named
2 · Independent

A learner says “the cow eats carbon dioxide from grass.” Rewrite this accurately.

Give me a hint

State what the plant stores and what the animal eats.

Compare my reasoning
  1. Photosynthesis incorporates carbon dioxide carbon into organic plant molecules.
  2. The cow feeds on plant organic material.

The plant uses photosynthesis to incorporate carbon dioxide carbon into organic molecules; the cow obtains that carbon by eating plant material.

Look for these in your work

  • Photosynthetic origin
  • Feeding transfer
3 · Transfer

Some carbon in food is not retained in animal tissue. Name two other routes for it in the cycle.

Give me a hint

Consider respiration and waste/decomposition.

Compare my reasoning
  1. Respiration releases carbon dioxide.
  2. Waste or dead material can be decomposed.

Some carbon can be returned as carbon dioxide by respiration; carbon in waste or dead material can be decomposed and eventually released by decomposer respiration.

Look for these in your work

  • Two routes named
  • Processes used accurately

Common mistakes

  • Treating carbon and energy as synonyms
  • Saying all ingested carbon becomes consumer tissue
  • Reversing the feeding direction
Recall without your notes

What can you explain now?

What is transferred by feeding in the carbon cycle?

Compare with the explanation

Carbon-containing organic material

Food moves carbon atoms from one organism to another.

After trying it yourself, choose your next review. This is your self-assessment.

Your review choice appears on Today. Sign in to sync it across devices.

Make it stick

Explain how feeding transfers carbon through a food chain, and name two ways carbon may leave an animal.

If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.

Keep learning Science — Combined

Course scope and assessment

This pathway maps all 121 detailed subject-content sections in the published 0653 syllabus for exams in 2028 and 2029. It adapts original lessons from the related single-science pathways and keeps Combined Science's narrower scope: Biology B1–B16, Chemistry C1–C12 and Physics P1–P5. A 0653-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The separate 2025–2027 syllabus has not been reconciled here; choose the 2028–2029 syllabus only.

StudyForA · Learn with understanding

Original teaching content and links to official sources. Check your exam year and qualification before using a resource.