Explain how the properties of water are important to marine mammals, such as whales, that live in cold ocean environments.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Whales are large mammals that live in cold oceans. They rely on water for many life processes, including maintaining a stable body temperature and carrying out chemical reactions inside their cells.
Model answer (5 marks)
1. Water’s high specific heat capacity means a large amount of energy is required to change its temperature.
2. Consequently, the ocean temperature changes slowly, providing a stable external environment for the whale.
3. Water is an excellent solvent; many substances dissolve in it.
4. This allows transport of dissolved substances such as glucose, oxygen, ions and minerals around the whale’s body via the blood.
5. Water also acts as a reactant in metabolic reactions, for example in digestion (hydrolysis) and other cellular processes.
2. Consequently, the ocean temperature changes slowly, providing a stable external environment for the whale.
3. Water is an excellent solvent; many substances dissolve in it.
4. This allows transport of dissolved substances such as glucose, oxygen, ions and minerals around the whale’s body via the blood.
5. Water also acts as a reactant in metabolic reactions, for example in digestion (hydrolysis) and other cellular processes.
Examiner tips
- Use the exact terms: specific heat capacity, solvent, reactant; link each property to a whale function.
- Structure answer as numbered points matching the mark scheme.
- Include examples (glucose, oxygen, hydrolysis).
Common mistakes
- Confusing specific heat with heat of fusion; using 'high density' instead of specific heat.
- Omitting the link between solvent property and transport of nutrients; writing vague statements like 'water helps whales survive'.
Mark scheme (5 marks)
- Water has a high specific heat capacity / large amount of energy needed to change water's temperature
- This means the ocean temperature changes slowly / stays relatively stable, providing a stable external environment for the whale
- Water is a solvent / many substances dissolve in water
- This allows transport of dissolved substances (e.g. glucose, oxygen, ions/minerals) around the whale's body in the blood / in solution
- Water is a reactant in chemical reactions (e.g. digestion / hydrolysis) inside the whale's cells / used in 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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