The Biological Importance of Water

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The Biological Importance of Water for Living Organisms

Water is made up of two elements, 2 positively charged hydrogen molecules and one negatively charged oxygen molecule. Water molecules have uneven charge distribution as one end of the molecule is slightly positive and the other slightly negative, this is called polar. Ionic substances such as sodium chloride dissolve easily in water because the positively and negatively charged ions are separated due to the dipole nature of water. As water is dipolar, the positively charged atoms of one water molecule attracted the negatively charged molecule of another water molecule. This is called hydrogen bonding. The hydrogen bonding between each molecule results in water being liquid at room temperature as it takes a lot of energy to turn it into gas due to its high heat capacity. Hydrogen bonding makes water extremely cohesive. Cohesion is the attraction between molecules of the same type (e.g two water molecules). Water is very cohesive due to the dipolar nature of the molecule. Cohesion helps the water to flow which is important in its transportation and enables substances to be easily dissolved and transported. Waters dipole nature also makes it a good solvent. A lot of substances which take part in biological reactions are ionic, which means they are either made of one positively charged atom or molecule, or one negatively charged atom or molecule. As water is dipole, it means that the positively charged hydrogens will be attracted to the negative atoms or molecules, and the negatively charged oxygen will be attracted to the positively charged atoms or molecules, resulting in ions being totally surrounded by water molecules. In other words, the atoms or molecules will be dissolved by the water.

Water is important to living organisms because its molecules can move freely enabling chemical reactions to occur easily in solution. For example, seminal fluid is mostly water which enables fertilisation to occur...
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