My question is:-
Only liquid water supports almost every living organism's metabolism, neither the vapour nor the condensed form of water does so. What is the chemical & the biological reason behind this fact?
My question is:-
A layman's view of the problem :
Let's assume that water in liquid form was not necessary and organisms could survive on solid or gaseous water. What would some of the difficulties be to sustain such a life form?
Solid Form of water
- How would the organism move without breaking or tearing itself apart? How would essential substances be transported from one part to another of the organism body?
- What would be the size of the organism? Gas has a much bigger volume than water.
- In order to transport nutrient molecules within the a gaseous body, a huge air pressure needs to be generated. Also, how will gravity be overcome while transporting these molecules? A lot of energy will be required to maintain such pressures.
I guess nature (which always takes an optimal path) asked such questions and found that water in it's liquid form was the most suited to support life on Earth.
It need not be water alone. Other liquids may be able to support life as well. Only, we haven't discovered them yet. But whatever the substance, it's liquid form would seem to be an optimal solution for life.
Organisms evolve to fit the environment they are in and all of earths organisms have a typical body temperature of above 0C and 100C, the freezing and boiling points of water respectively. So water at this temperature is liquid and we have evolved to carry out reactions at this temperature and use water as the solution for many reactions.
But why couldn't we have just done the same for water as a gas or a solid. Well as a gas it takes up a much larger volume, phenomenally higher and therefore we would either need to be massive or use high pressures. Additionally, containing reactions that carried out at this temperature with probably huge releases of energy is incredibly difficult. As a solid it is difficult to mobilise. As we dissolve essentially all of our bodies nutrients in water, or use the hydrophobic properties of fats to mobilise lipid soluble things, it would be incompatible with life. We rely very strongly on the ability of water to flow. Solids can't.
An interesting question is why water and not another liquid?