Connect respiration energy with movement and transport
Explain three cellular uses of released energy.
Section B12.1 · Respiration
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
- Recall cell processes, enzymes and the distinction between gas exchange and breathing.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which process moves a substance against a concentration gradient?
What you will learn
- Energy release supports cell work
- Transport and temperature control
Connect respiration energy with movement and transport
| Feature | Meaning |
|---|---|
| Muscle contraction | Energy for movement |
| Active transport | Energy for uptake against a gradient |
| Temperature regulation | Energy supports a constant body temperature |
Energy release supports cell work
Respiration releases energy from nutrient molecules through chemical reactions in cells. The energy is used for biological work rather than being created from nothing. Muscle contraction is one required use: muscle cells need an energy supply when their contractile components produce movement, including movements that are not consciously controlled.
Movement is not the definition of respiration. A resting organism still has cells performing other tasks. In an explanation, name the process that uses energy and connect it with respiration; simply writing that food makes a person move leaves out the cell reactions and energy link. A muscle can use both aerobic and anaerobic pathways under different conditions.
Transport and temperature control
Active transport moves substances across membranes against their concentration gradient using energy. Diffusion down a concentration gradient is not active transport and does not require the same cellular energy input. A root cell accumulating mineral ions against a gradient provides an example of why a plant, as well as an animal, needs energy from respiration.
Maintenance of a constant body temperature is another required energy use in organisms that regulate it, such as humans. Heat released by metabolism and energy-demanding responses help that regulation. Do not claim that every organism holds the same constant temperature, or that respiration only becomes necessary when somebody exercises or feels cold.
Sources for this lesson
Pause and explain
Why can a resting human still need respiration?
Worked example
A root cell takes up ions against their concentration gradient. Connect that to respiration.
Show the worked solution
- The uptake is active transport.
- Energy released by cellular respiration supports it.
Answer Respiration supplies energy for active transport of ions against the gradient.
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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.
Name the energy use when the heart muscle contracts.
Give me a hint
Identify the cellular work, not the whole breathing process.
Compare my reasoning
- Heart tissue includes muscle cells.
- Contraction needs an energy supply.
Muscle contraction uses energy released by respiration.
Look for these in your work
- Name contraction
- Link released energy
Correct: diffusion and active transport both require energy from respiration to move particles across a membrane.
Give me a hint
Check movement relative to the concentration gradient.
Compare my reasoning
- Diffusion is net movement down a gradient.
- Active transport against a gradient requires energy.
Active transport requires energy; diffusion down a gradient does not require that cellular energy input.
Look for these in your work
- Distinguish the two processes
- Retain the gradient link
A resting person is regulating body temperature. Does no visible movement prove that respiration has stopped?
Give me a hint
Energy use can continue without visible movement.
Compare my reasoning
- Temperature regulation is a required energy use.
- Other cell processes also continue at rest.
No. Respiration still supplies energy for temperature regulation and other continuing cellular work.
Look for these in your work
- Reject the visible-movement inference
- Name a continuing energy use
Common mistakes
- Calling all movement respiration.
- Calling diffusion energy-dependent active transport.
What can you explain now?
Why can a resting human still need respiration?
Compare with the explanation
Cells still use energy for processes such as active transport and temperature regulation
Movement is only one use.
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Make it stick
Name three energy uses and distinguish active transport from diffusion.
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.