# Explain why cells need a continuous supply of energy from respiration, referring to THREE different uses of energy in living organisms.

> Pearson Edexcel A-Level Biology A (9BI0) — Topic 5 Energy for Life · Explain · 5 marks

> All living cells require a constant supply of energy to carry out the processes that keep them alive. This energy is released from glucose during respiration.

## Mark scheme (5 marks)

1. Energy is needed for muscle contraction / movement
2. Correct explanation linking muscle contraction to a life process (e.g. muscles need energy to contract so that the organism can move / breathe / pump blood)
3. Energy is needed for active transport (moving substances against a concentration gradient across cell membranes)
4. Energy is needed for synthesis of large molecules / building new molecules (e.g. proteins from amino acids / DNA replication)
5. Energy must be supplied continuously because cells cannot store enough energy for long / respiration releases energy from glucose constantly to meet ongoing demands

## Key terms

- [respiration](https://www.gradenine.co.uk/glossary/respiration)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-cells-need-a-continuous-311b3944) · Published by Druglandscape Ltd.