If water is one of the biochemical components in creating life, how important is liquid water on a planet? Do you think having liquid is enough to sustain life? Support your answer.

Answer 1

Liquid water is necessary but not sufficient for the existence of life as we know it. Water has a number of unique properties that make it very useful to living organisms. It is not electrically charged, but it does have some mild charge polarity due to a phenomenon called electronegativity, which means that the electrons in water spend more of their time around the oxygen atom than the hydrogen atoms. Together, these qualities allow water to move through many biological membranes, but also to serve as solvent for electrically charged particles (electrolytes) which are vital to many biological processes. Water also has a very high specific heat, which is the amount of heat required to raise the temperature of a small amount of water. This means that water tents to resist sudden changes in temperature, which means that it can provide a moderating effect on the environment (coasts tend to have lower temperature extremes than inland areas for this reason) and it also means that living organisms, which are largely composed of water, do not tend to quickly freeze when the external temperature drops below freezing, or to quickly dry up and wither away when the outside environment heats up. Water's physical properties include the fact that it evaporates at temperatures that overlap with the temperatures of living creatures, which means that some creatures, including humans, can sweat to have the evaporating water carry away excess heat, which makes us more able to live in hot environments. There are many other characteristics of water which come into play, but these should show why water is necessary for life. However, liquid water is only one of MANY characteristics which are required to sustain life, such as how much energy is available in the environment for the life to subsist on (e.g. heat at deep geothermal vents), what chemicals are available to build cells out of, whether the environment is too extreme or volatile for living cells to hold together (e.g. extreme heat or acidity may make cellular survival difficult, though some extremophiles are able to survive in harsh conditions), and other factors. This is why, although it is necessary for life, having liquid water present is not sufficient for it to exist.