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The Role Of Water In Living Organisms

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The Role Of Water In Living Organisms Water has a great number of roles in living organisms, this is largely to do with the structure and covalent bonding in a single water molecule, and between water molecules. Around 75% of the earth is covered in water, and it is reffered to as the most important Biochemical. Its chemical symbol is: H2O In a water molecule there are two bonding pairs and two non-bonding pairs of electrons. These four pairs of electrons repel one another, forming a tetrahedral pattern. Because they repel they are as far from each other as possible. The two electrons in each of the oxygen-hydrogen bond are not shared equally. They are more strongly attracted to the oxygen. The bond is polar, it has a 'negative part' (the oxygen) and a 'positive part' (the hydrogen).The hydrogen bond is very weak, about ten times weaker than a single covalent bond. ...read more.


Also many organisms living in water spend most of their lives underwater, yet they require oxygen to live and respire, and as water is such a good solvent the required oxygen gas is dissolved in the water and the organisms can use it. Water is the most abundant component in any organism, proving its importance, the lowest is 20% in seeds, while jellyfish are about 99% water. Around 60% of the human body consists of water. It plays roles in the metabolism of all cells and for plants in photosynthesis. It is a main reactant in the photosynthesis reaction: CO2 + H2O -->-->-->--> C6H12O6 + H20 In all cells, water is used for hydrolysis, which is the breakdown of a substance by water, like polysaccharides to monosaccharides, forming a glycosidic bond. Water is used as a medium for chemical reactions, due to its properties as a solvent; the diffusion and osmosis of substances, e.g. ...read more.


Water can also be used for support. As plant cells have cell walls as well as cell membranes, when the plant cell becomes full of water (osmosis) it wont burst but the cell wall exerts a force equal to the osmotic force, the cell becomes turgid and this is important in the support of leaves and prevents wilting, as too little water makes the cells become flaccid which causes the plant to wilt. Temperature of water remains constant (due it to its high specific heat capacity) so few temperature controls are needed. So a high temperature is required to heat a small amount due to the overall strong bonds between molecules. Water has a high latent heat of vapourisation, which is the energy required to change a certain amount of of water in liquid form, into a gas, as water vapour. Water is used in perspiration to help regulate body temperature as it uses the heat from the body to vapourise the sweat taking away the heat and cooling the skin. ...read more.

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