Give the properties of water.

Answer: Properties of water important for living organisms:

1. Universal solvent: being a polar molecule it dissolves more substances than any other liquid, so it is the medium for all biochemical reactions and for transport.
2. High specific heat: it absorbs much heat with little rise in temperature, so it keeps the temperature of organisms stable.
3. High latent heat of vaporisation: evaporation (transpiration, sweating) has a cooling effect.
4. Cohesion and adhesion: water molecules attract one another (hydrogen bonds) and also the walls of xylem, giving high tensile strength and capillarity, which help the ascent of sap.
5. High surface tension.
6. It is transparent, so light reaches aquatic plants, and it is neutral (pH 7).
7. It has maximum density at 4 °C, so ice floats and aquatic life survives below it in winter.