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