Properties of Water

Water as a solvent
Any molecule that can interact with water is able to dissolve in it. Polar molecules (uneven charge) and ions (charged) are able to dissolve. On contact with water the polar molecule/ions are surrounded by water molecules. The clustering of water molecules separates the ions or polar molecules from each other – they are dissolved.
Importance
If molecules are dissolved they can move around and react with other molecules. This is the basis of most metabolic reactions in cytoplasm of cells.

Water and Thermal stability
Water does not change temperature easily. A large increase in heat energy results a relatively small rise in temperature. Energy is needed to break hydrogen bonds that form between water molecules.
Importance
This means that large bodies of water stay at fairly constant temperatures. They provide stable environments for living organisms. Also internal body temperature fluctuate less.
This is especially important when considering water as a transport medium (e.g. blood, lymph, xylem and phloem).

Water and changing state.
A large amount of heat energy is also needed to turn water into a gas, again this is due to the hydrogen bonding.
A large amount of energy needs to be transferred from water before it turns to a solid (ice)
Importance
As a result a lot of energy is needed to evaporate– this is an effective way for cooling the body (sweating and panting).
As a result water has a very high boiling point so water remains liquid over a large temperature range – again providing a stable environment to live.
This is especially important when considering water as a transport medium (e.g. blood, lymph, xylem and phloem).