Water has often been called the ‘universal solvent’ because it has had more substances dissolve in it than any other solvent. Often in living organisms, usually the substances have to be in a solution in order to receive the solute. For example, plants receive minerals in a solution; human digestion can only be dissolve soluble foods.
Also many water organisms almost all of their time under water. They need oxygen gas to breathe, and since by good luck that water is such a good solvent, the oxygen from the atmosphere is dissolved in the water. Four parts of oxygen will dissolve one hundred parts of water, and this surprisingly is adequate for the aquatic life to survive.
For Transport: water molecules tend to stick together because of the presence of hydrogen bonds making them cohesive. This characteristic is quite important in the transport of materials in solutions inside organisms. Organisms will produce a lot of substances, which have to be transported to other parts of that organism. Water does the job nicely of transporting the goods from one end to another. In plants, sap is used to transport the minerals and food around the plant, as does blood in the human body to transport hormones, food, oxygen and so on. Both of these forms used for transports are mainly composed of water.
As a Coolant: water has a high specific heat capacity of about 4200J/kg degrees Celsius, in other words as a result of the hydrogen bonds, water has a better ability to resist temperature changes better than most other substances. Therefore, a large amount of energy is needed to split up the forces between the water molecules to transform it from a solid to a liquid, or a liquid to a gas. When mammals heat up, we tend to sweat as a way to reduce our body temperatures. Now since it takes a lot of heat to convert it from a liquid to a gas, when we sweat our heat energy from out body is used to evaporate the water from our sweat, which eventually cools us down. This is because when a substance evaporates, the surface of the liquid remaining behind cools down. This occurs as the molecules with the most energy (the hottest ones) tend to vapourize first
As a Habitat: most life started out in water, and although there is a lot of life on land now, water is still a model medium to thrive and live in. There are many reasons to justify why water this is the case. Firstly water in large quantities and mass serves as a protective shield for the aquatic life and cells that would be threaten to be dried up on land. Secondly, waters ability as an efficient and effective solvent to supply the marine life with the nutrients and oxygen they need through diffusion, and to serve to remove waste products. For example, oxygen is dissolved in the water, where the water will pass through fishes allowing the oxygen to diffuse into their blood stream. Then the carbon dioxide is diffused into the water, later to be removed. Thirdly, as a large mass, the temperature of water will vary very mildly so organisms living deep within oceans and lakes will have no need for temperature control instruments, unlike land organisms. Also, water filters out harmful ultra-violet rays from the sun, protecting the water life from any further damage.
As a Lubricant: lubrication is vital for where bones meet at joints, this is to ensure that that the two bones do not rub and scrape each other causing damage the pain to the animal. This enables easy smooth motions greatly reducing the friction involved. A synovial membrane at joints surrounds a fluid called synovial fluid, which acts as the lubricant, water being a major ingredient in this fluid. Not only joints are protected by fluids, other internal organs are surrounded by watery fluids that protect, lubricate and much more. For instance eyes contain aqueous and vitreous humours to maintain the shape of the eye, help focusing, allow nutrients and oxygen to freely diffuse through the eye. Also to help food pass more easily through the gut, an important lubricant called mucus is used.
As a Key Role in Ensuring the Survival of Marine Life in Winter: one unusual property of water is that in a solid form it is less dense than if it were a liquid. Hydrogen bonding between the water molecules is that liquid water has a maximum density at 4 degrees Celsius because the solid (ice) has an open structure created by the ordered hydrogen bonds. This all means that in a big mass of water e.g. a pond or lake, the water at the bottom in winter will be 4 degrees Celsius. In winter the tops of ponds and parts of lakes will freeze over, the temperature at the surface will be freezing, but the temperatures deeper down in the pond will be near 4 degrees Celsius. Normally colder water would sink to the bottom of the pond, but due to waters ability to be most dense at 4 degrees Celsius, the warmer water stays at the bottom supporting the colder water on top. Therefore the temperatures at the bottoms of lakes don’t alter very much, thus allowing aquatic life to survive cold winters.
Water is truly a unique molecule, quite in a field of it’s own. I have been unable to name all the numerous aspects of how water is of an importance to biological life due to the fact that there are so many ways in which water incorporates itself back into our daily lives, mostly oblivious to the fact of how important and crucial it is to the survival of life on this planet.
