Explain why water is important for the survival of organisms living in hot desert environments. Refer to the properties of water in your answer.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Desert organisms such as cacti and camels must cope with extremely high temperatures and limited water availability. Despite these challenges, water remains essential for their survival.
Model answer (5 marks)
Water is a universal solvent, so it dissolves ions and organic molecules, allowing nutrients and waste products to be transported in the blood and within cells.
The dissolved substances can then be carried throughout the organism, enabling metabolic processes.
Water has a high specific heat capacity, meaning it requires a large amount of energy to change its temperature.
This property helps maintain a stable internal body temperature, preventing overheating in the hot desert.
Finally, evaporation of water from sweat or transpiration removes heat energy from the organism’s surface, providing a cooling effect.
The dissolved substances can then be carried throughout the organism, enabling metabolic processes.
Water has a high specific heat capacity, meaning it requires a large amount of energy to change its temperature.
This property helps maintain a stable internal body temperature, preventing overheating in the hot desert.
Finally, evaporation of water from sweat or transpiration removes heat energy from the organism’s surface, providing a cooling effect.
Examiner tips
- Use the exact terms: solvent, dissolved substances, specific heat capacity, evaporation
- Show the causal chain: solvent → transport → temperature regulation → cooling
Common mistakes
- Confusing water’s high heat of vaporisation with its specific heat capacity
- Omitting the role of evaporation in cooling
Mark scheme (5 marks)
- Water is a solvent / water dissolves substances
- Dissolved substances can be transported around the organism / in the blood / in cells
- Water has a high specific heat capacity / requires a lot of energy to change temperature
- This helps maintain a stable / constant internal body temperature / prevents overheating in the heat of the desert
- Evaporation of water (in sweat / transpiration) cools the organism / removes heat energy from the surface
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Water questions
- Explain how the properties of water allow animals living in ponds to survive dur…
- Explain how the properties of water are important to marine mammals, such as wha…
- Explain how the properties of water are important to organisms that live in rock…
- Explain how the properties of water are important during the chemical reactions …
- Explain how the properties of water are important to plants living in environmen…
- Explain how the properties of water are important during sweating as a mechanism…