Explain how the properties of water allow animals living in ponds to survive during periods of intense heat in summer.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
During hot summer months, air temperatures can rise significantly. Pond-dwelling animals such as fish and invertebrates must be able to survive these conditions.
Model answer (5 marks)
Water has a high specific heat capacity, so it can absorb large amounts of heat before its temperature rises, keeping pond water temperature relatively stable during hot days.
Water also has a high latent heat of evaporation; when it evaporates, it removes heat from the pond, cooling the water slowly and preventing rapid temperature spikes.
Because water is an excellent solvent, dissolved oxygen, minerals and nutrients stay in solution, allowing fish and invertebrates to maintain respiration and metabolic processes even when surface temperatures are high.
Water also has a high latent heat of evaporation; when it evaporates, it removes heat from the pond, cooling the water slowly and preventing rapid temperature spikes.
Because water is an excellent solvent, dissolved oxygen, minerals and nutrients stay in solution, allowing fish and invertebrates to maintain respiration and metabolic processes even when surface temperatures are high.
Examiner tips
- Use the word ‘specific heat capacity’ and ‘latent heat of evaporation’ – these are key terms. Show the link between high heat capacity and stable pond temperature. Explain how evaporation cools the pond and keeps water levels. Mention the importance of dissolved oxygen for aquatic life.
- common_mistakes
- :
- Confusing heat capacity with thermal conductivity. Forgetting to link evaporation to cooling rather than just water loss. Using vague phrases like ‘water stays cool’ without explaining the mechanism.
Mark scheme (5 marks)
- Water has a high heat capacity / specific heat capacity
- So the temperature of the pond water changes slowly / remains relatively stable, protecting animals from rapid temperature fluctuations
- Water has a high latent heat of evaporation / vaporisation
- So the pond loses water / cools slowly through evaporation, helping to maintain water levels / keeping the pond cool without losing large amounts of water
- Water is a good solvent so dissolved oxygen / minerals / nutrients remain in solution, allowing animals to absorb them / carry out metabolic reactions
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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