Connect chemical energy with processes in organisms
Organisms transfer chemical energy through cellular processes, and some energy is transferred to their surroundings.
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
- Respiration is taught in 12.1–12.3; it is not the only transfer route. Use the energy account without adding routes beyond the evidence supplied.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What can happen to chemical energy in an organism?
What you will learn
- Describe chemical energy being used in living organisms
- Explain that energy can be transferred to the environment during life processes
Follow energy within an organism
Chemical energy in organic molecules can be transferred during cellular respiration and other metabolic processes. Cells use energy transfers to support functions such as movement, active transport, growth and maintaining internal conditions.
The organism is a stage in the energy pathway. Some chemical energy remains in molecules in its tissues; some is transferred into other forms and can be transferred to the surroundings, including as heat.
Use “transfer” rather than “loss” as if energy vanished
Biology diagrams often say energy is lost from an organism or food pathway. In an energy account, this means it has been transferred out of that biological store or route, commonly to the environment as heat. Energy is not destroyed; it is transferred.
The syllabus asks for the eventual transfer to the environment; it does not ask for a detailed energy budget in this section. Respiration is not the only transfer route. Describe the route qualitatively unless numerical measurements are explicitly supplied.
Sources for this lesson
Pause and explain
A diagram shows chemical energy in an organism and an arrow labelled “heat to surroundings.” What does the arrow mean?
Worked example
A mammal respires and maintains body temperature. How can energy be described as remaining in the organism and transferring to the environment?
Show the worked solution
- Identify chemical energy in organic molecules as the starting store.
- Describe transfers that support cellular processes and heat transfer to the surroundings.
Answer Chemical energy in organic molecules is transferred during respiration and metabolism; some supports cell processes and some is transferred to the environment as heat.
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 runner uses chemical energy in food during movement and becomes warmer. Describe two destinations or forms in the energy account.
Give me a hint
Name the starting store and the transfers.
Compare my reasoning
- Chemical energy in food is transferred during respiration and cell activity.
- Some supports movement; some transfers to the surroundings as heat.
Chemical energy is transferred from food molecules to support movement, and some energy is transferred to the environment as heat.
Look for these in your work
- Starting form identified
- Both outcomes described
A pupil says “the plant loses energy when it respires, so the energy no longer exists.” Correct the explanation.
Give me a hint
Explain what “lost from the organism” means.
Compare my reasoning
- Respiration transfers chemical energy in organic molecules.
- Some energy supports cellular processes and some transfers to the surroundings.
Energy is not destroyed. During respiration it is transferred; some supports cell processes and some leaves the plant’s biological store, for example as heat to the environment.
Look for these in your work
- Conservation wording
- Destination explained
A classroom model shows a plant receiving light, storing chemical energy and later releasing heat to the air. Which part is the biological store, and what does the outward arrow show?
Give me a hint
Distinguish the store from an energy transfer.
Compare my reasoning
- Chemical energy in the plant’s organic material is the store.
- The heat arrow represents transfer from the plant to the environment.
The store is chemical energy in organic molecules in the plant. The outward arrow shows energy transferring to the environment as heat, not being destroyed.
Look for these in your work
- Store identified
- Outward transfer interpreted
Common mistakes
- Saying energy is destroyed during respiration
- Claiming all chemical energy stays in body tissue
- Confusing energy transfer with movement of matter
What can you explain now?
What can happen to chemical energy in an organism?
Compare with the explanation
It can be transferred during cellular processes and to the surroundings
Energy transfers support life processes and may reach the environment.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain how chemical energy in an organism can support life processes and eventually reach the environment.
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.