Explain energy transfer to the environment
Energy that enters and moves through organisms is eventually transferred to the environment rather than cycled back as the same biological store.
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
- Use the energy-flow route from 19.1; nutrient cycles are covered separately in 19.3.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What happens to energy as it passes through biological systems?
What you will learn
- Describe eventual transfer of energy to the environment
- Distinguish energy flow from a cycle of matter
Original qualitative energy-flow schematic; arrows show direction, not measured amounts.
Follow energy beyond an organism
Energy can enter as sunlight, become chemical energy in living material and pass through organisms. During life processes, including respiration, some energy is transferred to the surroundings, often as heat. Energy in organic material may also pass to other organisms when feeding occurs.
The pathway eventually transfers energy to the environment. It is not a closed loop that returns the same energy store to the Sun or makes the energy reusable by a plant. New energy input continues to enter the system.
Do not confuse energy with recycled atoms
Matter such as carbon can be rearranged and cycle between organisms and the environment. Energy has a different pathway: it flows through biological systems and eventually transfers to the environment. A diagram can show both, but their arrows should not be treated as the same process.
The term “energy lost” may mean energy has left a particular organism or route. For accuracy, name a destination such as the environment and, when relevant, heat. Do not say it has disappeared.
Sources for this lesson
Pause and explain
Which description distinguishes energy flow from matter cycling?
Worked example
A student draws Sun → plant → rabbit → environment and then an arrow from environment back to the Sun labelled “same energy recycled”. Evaluate the final arrow.
Show the worked solution
- Retain the one-way transfers through organisms.
- Explain that energy eventually transfers to the environment; new input comes from the Sun.
Answer The final arrow is misleading. Energy flows through the biological system and eventually transfers to the environment; the system receives new energy input from the Sun rather than recycling the same energy back.
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 diagram shows energy entering as light and later leaving an organism as heat. State what happens to the energy in between and at the end.
Give me a hint
Use “transfer” and name the endpoint.
Compare my reasoning
- Light energy can be transferred into chemical energy in organisms.
- Energy moves through biological processes and eventually transfers to the environment, including as heat.
Energy is transferred from light to chemical stores in organisms, passes through biological processes and eventually transfers to the environment, for example as heat.
Look for these in your work
- Forms in pathway
- Environment endpoint
A learner writes “energy cycles between plants, animals and the Sun just like carbon.” Explain the correction.
Give me a hint
Separate energy from matter cycles.
Compare my reasoning
- Energy flows through organisms and ultimately transfers to the environment.
- The biological system receives new input from sunlight; do not draw a closed energy loop.
Energy does not cycle as carbon matter does. It flows through organisms and eventually transfers to the environment; new light energy enters from the Sun.
Look for these in your work
- Energy and matter separated
- No closed loop
In an ecosystem sketch, arrows show energy in food and heat reaching the air. A classmate calls the air arrow “energy loss.” Give a more precise description.
Give me a hint
“Loss” is relative to the organism’s store.
Compare my reasoning
- State that energy transfers out of the organism.
- Name the environment and the heat form.
The energy is transferred out of the organism to the environment as heat; it is not destroyed.
Look for these in your work
- Transfer phrasing
- Destination named
Common mistakes
- Drawing energy as a closed cycle
- Saying transferred energy disappears
- Confusing the carbon cycle with energy flow
What can you explain now?
What happens to energy as it passes through biological systems?
Compare with the explanation
It is eventually transferred to the environment
This is the stated endpoint of the energy flow.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Describe the eventual destination of energy in biological systems and contrast the pathway with cycling matter.
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.