Evaluate the claim that ATP is a better immediate energy source for cells than glucose.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
ATP releases energy in small, manageable amounts suitable for cellular reactions.
ATP transfers energy directly and immediately to reactions without further digestion or processing.
Glucose must first be broken down by respiration to release its energy, which takes time.
Glucose contains more stored chemical energy than ATP and acts as a long‑term energy store, whereas ATP is a short‑term store.
Conclusion: ATP is a better immediate energy source because it delivers energy directly to reactions, but glucose is superior for long‑term and large‑scale energy storage.
ATP transfers energy directly and immediately to reactions without further digestion or processing.
Glucose must first be broken down by respiration to release its energy, which takes time.
Glucose contains more stored chemical energy than ATP and acts as a long‑term energy store, whereas ATP is a short‑term store.
Conclusion: ATP is a better immediate energy source because it delivers energy directly to reactions, but glucose is superior for long‑term and large‑scale energy storage.
Examiner tips
- Use the word "evaluate" to show both strengths and weaknesses of the claim.
- Mention the time‑scale of ATP release versus glucose breakdown.
- Include a clear, reasoned conclusion that balances the two points.
Common mistakes
- Focusing only on the amount of energy in glucose and ignoring the immediacy of ATP.
- Using vague terms like "more energy" without explaining the difference in storage and release.
- Failing to give a balanced conclusion that acknowledges both ATP and glucose roles.
Mark scheme (5 marks)
- ATP releases energy in small, manageable amounts (suitable for cellular reactions)
- ATP transfers energy directly / immediately without further digestion or processing
- Glucose must first be broken down (by respiration) to release its energy
- Glucose contains more stored chemical energy than ATP / glucose is a long-term energy store whereas ATP is a short-term energy store
- Reasoned conclusion — e.g. ATP is a better immediate source because it releases energy directly to reactions, but glucose is better for long-term/large-scale energy storage
Key terms in this question
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Evaluate" question →
- Decode the mark scheme abbreviations →
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