The Biological Importance of Water

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Water is a polar molecule, which means it has areas of slightly and slightly negative areas of charge. This is because of the electronegativity of hydrogen and of oxygen. Electronegativity is the ability of an atom to attract electrons in a covalent bond. In water, oxygen has a much higher electronegativity, so the shared electrons are attracted slightly more towards the oxygen, making the oxygen slightly negative and the two hydrogens slightly positive. Adjacent water molecules are attracted to each other, forming hydrogen bonds between the slightly positive hydrogen and the lone pairs of electrons from the oxygen. Hydrogen bonds are quite strong compared to other intermolecular forces, allowing the water to be very stable. This gives it a high boiling point and a high SHC. Each water molecule has the potential to form four hydrogen bonds which makes the boiling point much higher than other hydrogen bonded compounds. Water sticks to itself due to the polarity, and this is called cohesion. However, another property of it is adhesion, which is usually stronger than the cohesive forces. This is why it spreads out on surfaces like glass, as it is more attracted to that than itself. The polarity also allows water to act as a solvent, giving it the nickname of ‘the universal solvent’. These properties allow many biological functions to take place. In plants, many molecules including hormones and sugars are transported in solutions. Cohesion and adhesion allow this to take place as the water sticks to itself and the walls of the tube, and its low viscosity allows it to flow through. Water is a good environment for chemical reactions such as photosynthesis and respiration because of its thermal stability and solvent properties. It is also essential in keeping plant cells turgid, which is important so the plant has a large surface area for photosynthesis. Water is

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