Transfer carbon by feeding
Feeding moves carbon-containing organic molecules from a producer to consumers and between consumers.
Section 19.3 · Nutrient cycles
Exam scope and assessment notes
Core and Extended · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
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.
Pause and explain
Which path correctly follows carbon in a food chain?
Worked example
A grasshopper eats a leaf and a frog eats the grasshopper. Trace carbon through these feeding events.
Show the worked solution
- The leaf contains carbon in organic molecules.
- 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.
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
- The cow eats crop plant material.
- 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
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
- Photosynthesis incorporates carbon dioxide carbon into organic plant molecules.
- 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
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
- Respiration releases carbon dioxide.
- 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
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.
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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.