The Biological Importance of Water Essay

Submitted By flossy48
Words: 1363
Pages: 6

The Biological Importance of Water

Water is essential to us humans and all other living organisms, without it life on Earth would not exist. Water as a molecule is quite peculiar and it is its unusual properties that give it the ability to sustain life.
Water has the molecular formula of H2O, this means that there are two Hydrogen atoms (H) and one oxygen atom (O). The water molecules layout could be described as a Mickey Mouse head; the face being the oxygen molecule and the ears being the hydrogen molecules. Water is a dipolar molecule this means that one end is slightly positively charged (the hydrogen) and the other is slightly negatively charged (the oxygen), because of the dipolar charges water molecules attract each other, and this is called cohesion. Cohesion is when the oxygen atom of one water molecule forms a hydrogen bond with the hydrogen atom of another water molecule (opposite charges attract), cohesion can also occur between other molecules of similar substances.
Water molecules on the surface of the water form hydrogen bonds with the surrounding water molecules but not with the molecules in the air, the unequal distribution of bonds enables the water to form a force called surface tension, this causes the water to form a sort of tough ‘skin’. This is important because it keeps the water as a singular body, protecting itself from disruption. It can also be important for insects, such as pond skaters, and other life forms, such as birds, because it enables them to sit on the surface of the water.
Water can also form hydrogen bonds with polar substances; this is why water feels ‘wet’. The water molecules actually stick to other molecules with hydrogen bonds, causing a thin layer of water to form on the surface of a material, but because of the cohesion force the water never forms a flat layer. The molecules stick to each other to form circular drops called ‘droplets’. When oil is mixed with water, because of it non-polar properties it does not dissolve, it simply sits on the surface in a droplet, it does this because the oil is cohesive to itself and less dense than water. These bonds are weak and so the water can easily move and break away from the material, this intermolecular bonding is known as adhesion. This ‘sticky’ property enables water to move, unbroken, up the xylem tissue of plants up to the leaves to be used in photosynthesis. Photosynthesis is a process that plants us to turn water and carbon dioxide into glucose and oxygen (6H2O + 6CO2 -> C6H12O6 + 6O2). This process is essential for the plants to have energy and for the production of oxygen, which is essential for other organisms in allowing them to perform the process of respiration.
Water is also essential for other biochemical reactions such as peptide bonding for protein formation, without proteins life would not exist. Proteins perform the majority of functions within a living organism, for example; catalyzing metabolic reactions, responding to stimuli, replicating DNA and transporting molecules from one location to another. Water forms the peptide bonds that hold the amino acids together to form proteins such as enzymes. Enzymes are biological catalysts, they depend on water to reach their substrates and bind to them. There is no enzymatic activity without water. In addition, enzymes depend on sufficient pH interval to work and the pH is a consequence of the delivery of hydrogen cations (H+) and hydroxyl anions (OH-) by acids and bases in water solution.
Water is also essential in living organisms because it is a universal solvent, this means that the majority of solutes (polar and ionic substances), are attracted by the waters charges and break down in the water to form a solution. If the substance can dissolve in the water they are known as hydrophilic and non-polar substances that won’t dissolve are known as hydrophobic.
Biologically, the solvent properties of water are essential because this means that the water can transport…