Water has been called a universal solvent because of it polarity. This means it can easily ionise substances, Many compounds, whether ionic, polar or covalent will dissolve in it, therefore more reactions take place while in solution with water. Often in organisms substances must be in solution and water is the solvent. Plants can only obtain mineral salts in solution and human digestion will only dissolve soluble foods, meaning large starch molecules must be broken down into soluble sugars. Also many organisms living in water spend most of their time underwater, yet they require oxygen to respire, and as water is such a good solvent the required oxygen gas is dissolved in the water.

Water is the most abundant component in any organism, the lowest is 20% in se

It is also used on a much larger scale for transport. Blood is mostly water, and is used to transport food, hormones, waste products (ammonia and urea) and oxygen, similarly in plants, sap is used to transport food and other substances. These substances all easily dissolve in water and then can be transported, whether it be oxygen to tissues, or hormones to various organs. Water is also used during fertilization when sperm must reach the ovum, the sperm is transported in semen, which is mostly water.

Water can also be used to provide a habitat. Life originally evolved in an aqueous habitat and still provides an ideal habitat for a variety of life. This is for many reasons, a large mass of water around an organism can act as a protective shield, preventing the cells from drying out as they would on land; it provides support and buoyancy, so woody tissue and bones are not needed in such large amounts: due to its solvency and mobility nutrients can be easily supplied to an organism and waste products can be removed by diffusion (e.g. the gills of a fish): fertilization is much easier due to the surrounding water, and when offspring are produced they can more easily spread out, reducing the risk of competition; temperature rema

Some topics in this essay:
, solution water, water water, water due, plant cells, water organisms, waste products, solvent polarity, water solvent, transport food,