Properties of Water

Properties of Water

1. Solvent

   • Metabolic processes in all organisms rely on chemicals being able to react together in solution
   • 70-95% of cytoplasm is water. Dissolved chemicals take part in processes such as repiration and photosynthesis in living organisms

2. Liquid

   • The movement of materials around organisms, both in cells and on a large scale in multicellular organisms, requires a liquid transport medium
   • Blood in animals and teh vascular tissues in plants use water as a liquid transport medium

3. Cohesion

   • Water molecules stick together creating surface tension at the water surface. Cohesion also makes long, thin water columns very strong and difficult to break
   • Transport of water in teh xylem relies on water molecules sticking together as they are pulled up the xylem in the transpiration stream
   • Some small organisms make use of surface tension and have the ability to 'walk on water'

4. Freezing

   • Lakes tend not to freeze completely so aquatic animals are not killed as temperatures fall
   • Water freezes, forming ice on the surface. Water beneath the surface becomes insulated and less likely to freeze

5. Thermal Stability

   • Large bodies of water have fairly constant temperatures
   • Evaporation of water can cool surfaces by removing heat
   • Oceans provide a relatively stable environment in terms of temperature
   • Many land-based organisms use evaporation as a cooling mechanism, for example in panting or sweating

6. Metabolic

   • Water takes part as a reactant in some chemical processes
   • Water molecules are used in hydrolysis reastions and in the process of photosynthesis