The biological importance of water.

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The biological importance of water.

Water is a key factor in our life and despite it being only a simple molecule, it is vital for life. Without water any life would not exist on earth as it makes up about 60% of the body weight of humans and in all living cells alone it makes up 70-95% of the mass in the cell. This means that water is the main constituent of all organisms. In jellyfish, water makes up 96% of its body mass but in herbaceous plants water makes up 90% of the mass. Water is the most abundant liquid on earth, which isn’t surprising when it’s seen that two thirds (or more), in active living cells is made up of water, and that two-thirds of the world is covered by water too.

Our body takes in water by various different ways, by food (800), by drinking (1450), and by respiration (350). We take in roughly 2600cm3 of water per day. We release water from our body by urine (1500), sweat (600), evaporation from lungs (400), and in our faces (100). However the uses of water in our body is endless, and to understand is usefulness we must explore the structure or a water molecule.

The structure of the water molecule gives us an insight in to the main reason as to why water is found in all places in our body. It isn’t an ordinary molecule and because of its unusual chemical and physical properties it makes it’s an ideal constituent of all living things. One of the benefits of it’s structure means that water is known to be good at ionizing certain substances, and this therefore means that water is a good solvent. The importance of water being a solvent biology is key. It’s has often been called a ‘universal solvent’, as more substances can be dissolved in water than in any other solvent. For most functions in living organisms to take place the substances must be in solution, and it is water that usually makes the substances into a solution. This can be seen in plants, as plants can only take up absorb mineral salts that are in a solution form, in humans when large starch molecules are broken down into soluble sugars like glucose for digestion. In humans and plants gas exchange requires moist surface areas as gas exchange always takes place in solution. Also the fact that many organism still live or spend much of there time in water, but still need oxygen for respiration and to live, means they need oxygen in the water. This is possible as because water is such a good solvent it can dissolve the oxygen gas into it.

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Water is also used in the process of transport. Substances which organisms produce often need to be transported to different places in the organism. Blood is used in humans and animals to transport various substances round the body. E.g. hormones, oxygen, waste products etc. Sap is used in plants to transport food similar substances around the plant. Water plays a big part in this transportation method as blood and sap are mainly made up of water and the water dissolves the products that need to be transported.

Water can also be used as a mechanism of support. ...

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