The Uses of water in Living Things
Topics I have chosen to cover:
- Osmosis & Water potential
- Condensation & Hydrolysis Reactions
- Digestion – the importance of water
- Blood and tissue fluid
To emphasise the sheer importance of water in living things and to put the content of this essay in to perspective, I am firstly going to inform you that the human body is approximately 50-75% water. Without water our body would be unable to successfully perform the numerous complex reactions and processes required for our functioning. Throughout my essay I aim to present to you several uses of water particularly focusing on the human body’s reliance on water to function. To appreciate the important uses of water in living things it seems vital that we first explore the behaviour of water. As water is a polar molecule, substances are easily able to dissolve in it and this results in the formation of a solute/solvent mixture where the water molecules cluster around the solute, meaning there are less water molecules that are free to occupy the space surrounding the cluster and hence we say the concentration is lower than before. Water potential is a measurement of the free water molecules that are not clustered around the solute; it measures the tendency of such molecules to move down a concentration gradient and in to another area, represented by the unit (potential energy per volume). Pure water that does not contain any solute is said to be 0 on the concentration gradient scale and so if you were to then add solute to this water you would be decreasing the water potential, essentially making it less than zero and thus ‘more negative’. Water will always move from a region of higher water potential (where there is less solute) to an area of lower water potential to try and counteract the added solute and balance the concentrations. Water is also able to diffuse across a partially permeable membrane, which is fundamentally a membrane that will allow...
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