capacity in which it takes a large amount of energy to change its temperature. This is
vital to all living organisms which contain water, so they are able to maintain there
optimum temperatures for longer in adverse conditions.
The fact that water contains two hydrogen atoms and one oxygen atom is
essential for photosynthesis. During the light dependant stage, the hydrogen molecules
of water are seperated from the oxygen molecule. And in the light indipendant stage,
the hydrogen molecules from water, react with the carbon dioxide to form a
carbohydrate.
Water is relatively incompressable, it is able to maintain its shape. This allows
it to act as a hydrostatic skeleton in organisms such as earthworms and diploblastic
organisms like jellyfish.
The process of osmosis is only possible because of the size of the water
molecule. Because it is so small, water is able to travel through the semi-permiable
membrane of cells in living organisms, which larger molecules cannot fit through.
This is useful in plant cells, as water is lost in transpiration, it can easily be replaced
by this process. Creating a water column through the plant.
The viscosity of water is low. This allows it to move about with ease. Without
this, it wouldnt matter if nutrients could dissolve into it, or if it was small enough to
pass from cell to cell. The fact that water is bonded together so easily, allows it to
be used in all the different ways I have already highlighted.
Water is transparent,and this, believe it or not(!), allows our eyes to function.
The transparency of water allows it to be used as a cleaning compound on an
organisms eyes, without trapping any of the light rays that before they reach the
pupil.
EXPLAIN HOW THE PROPERTIES OF WATER MAKE IT SUITED
(B) AS AN ENVIRONMENT FOR ORGANISMS TO LIVE IN
The properties of water are essential for organisms to live in for a variety of
reasons. The one that is most evident is its transparencey. The fact that light can travel
through it allowed marine life millions of years ago to develop a more sophisticated
detection device other than sonar, sight. This is evident with many types of fish using
visual effects to deter predators, like schools of fish in a large mass to make it seem as
though they are bigger than they actually are. Or for predators to seek out food.
Coupled with the fact that light can travel through water, so can heat. Which is essential
for aquatic plants to photosynthesise.
Water, unlike most liquids, actually increases in volume and decreases in density
when frozen. This gives ice a boyancy, allowing it to float on top of a body of water
rather than sinking. This allows organisms that live in water to survive beneath the ice,
this has undoubtedley contributed towards the survival of life on earth.
Water is has a molecule of oxygen contained within it. This means that aquatic
organisms such as dogfish are able to extract that molecule for respiration using a series
of vascularized gills. Water is kept flowing over these gills by a specialized pumping
system. And it is due to the density of water, in comparison to air, that prevents the
gills from collapsing on top of each other. This is evident when a fish is taken out of
water.
The thermal capacities of water are important to the organisms living in it. Most
organisms require a stable temperature as part of there environment, and water has a
very high heat capacity. A large increase in heat results in a small rise in the water
temperature. Keeping the water temperature fairly constant, allowing organisms to
keep within there required temperature ranges.
Waters thermal capacities are also important on a more grand scale. The fact that
water has a high boiling point for a molecule so small means that water can exist on
many areas of the earth, and thus allow life to thrive in abundance.
The surface film formed between air and water is due to waters high surface
tension. This is caused by the polarity of water that causes the surface of water to
contract to occupy the smallest possible area. This is the basis for a habitat for
organisms that live on top of the water like pond skaters, whirlig beetles and raft
spiders.
Water is 800 times denser than air. And although the density of water causes
more friction for organisms moving or swimming through it than air. This property is
also suited towards organisms because it supports them. Therefore it is easier for some
of the larger organisms to support their weight.