Follow chemical energy during feeding
Feeding transfers chemical energy in organic material from one organism to another.
Section B18.1 · Energy flow
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Food-chain diagrams are treated in 19.2; this lesson focuses only on the energy transfer represented by feeding.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
When a rabbit eats grass, which energy transfer is represented?
What you will learn
- Describe energy transfer when an organism feeds
- Label energy arrows from food to consumer
Original qualitative energy-flow schematic; arrows show direction, not measured amounts.
Trace a feeding transfer
When a consumer eats another organism, it takes in organic material that contains chemical energy. Digestion and absorption make molecules available for cellular processes. Some chemical energy is transferred into the consumer’s own organic material.
A simple diagram may show plant → herbivore or prey → predator. The organism arrow represents transfer through feeding; if the question asks about energy, label the arrow “chemical energy in food” or “chemical energy transferred by feeding”.
Use the direction carefully
The energy arrow follows the transfer from the food organism to the consumer. It does not point back to the plant or to the Sun. The consumer does not receive all the energy present in the food because some energy is transferred elsewhere during life processes and some material may not be digested. During feeding, chemical energy in organic material transfers to another organism.
For this section, describe the direction and the chemical form. Detailed food-chain terms, trophic-level labels and efficiency calculations belong to later syllabus objectives; do not add them when the question only asks for the basic transfer.
Sources for this lesson
Pause and explain
Which arrow label best represents grass → rabbit when the rabbit feeds?
Worked example
In a grass → rabbit pathway, what energy transfer does the arrow from grass to rabbit represent?
Show the worked solution
- Identify the feeding event.
- Name the energy form in the grass material and the transfer to the consumer.
Answer The arrow represents chemical energy in organic plant material being transferred to the rabbit when it feeds.
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.
A bird eats a seed. Describe the energy transfer shown by seed → bird.
Give me a hint
Follow the direction of the feeding arrow.
Compare my reasoning
- The seed is organic material containing chemical energy.
- Some of this energy transfers to the bird during feeding.
Chemical energy in the seed’s organic material is transferred to the bird when it feeds.
Look for these in your work
- Direction correct
- Chemical form named
Correct this statement: “When a fox eats a rabbit, light energy moves from the rabbit into the fox.”
Give me a hint
Identify the form present in the rabbit tissue.
Compare my reasoning
- The rabbit tissue contains chemical energy in organic molecules.
- Feeding transfers some of that chemical energy to the fox.
The transfer is chemical energy in rabbit tissue moving to the fox through feeding, not light energy.
Look for these in your work
- Incorrect form replaced
- Transfer named
An invented feeding record says a lizard ate insects but leaves the amount of food unmeasured. What energy-flow statement is supported, and what cannot be calculated?
Give me a hint
Use the event qualitatively.
Compare my reasoning
- Feeding transfers chemical energy in insect material to the lizard.
- Without quantities, energy amounts or efficiency cannot be calculated.
The feeding transfers chemical energy from insect organic material to the lizard. The unmeasured record cannot supply an energy quantity or transfer efficiency.
Look for these in your work
- Supported route stated
- Calculation limit stated
Common mistakes
- Pointing the energy arrow from consumer to food
- Claiming the consumer receives all food energy
- Calling energy transfer a transfer of sunlight directly to the consumer
What can you explain now?
When a rabbit eats grass, which energy transfer is represented?
Compare with the explanation
Chemical energy in plant material transfers to the rabbit
Feeding passes chemical energy from food material to the consumer.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Describe the energy arrow for one feeding event, including its direction and chemical form.
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.