Water

• Water is a polar molecule due to the uneven distribution of charge within the molecule. The hydrogen atoms are more positive than the oxygen atom causing one end of the molecule to become more positive than the other. As a result hydrogen bonding between many water molecules can occur allowing them to stick together.
• It is a metabolite in metabolic reactions such as condensation and hydrolysis which are used in forming and breaking of chemical bonds.
• It is a solvent allowing gases to readily diffuse as well as enzymes and waste products.
• It has a high specific heat capacity. This is because water molecules stick together with hydrogen bonds meaning that a lot of energy is required to break these bonds. This helps to minimise temperature fluctuations in living things therefore it acts as a buffer.
• Hydrogen bonding means that it requires a lot of energy to evaporate 1g of water. Therefore water has a relatively large latent heat of vaporisation, meaning evaporation of water provides a cooling effect with litter water loss.
• Strong cohesion between molecules enables effective transport of water in tube like the xylem. The strong cohesion supports columns of water, as a result of strong cohesion the surface tension at the water-air boundary is high.