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The Biological Importance of Water

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Biological Importance of Water (10 marks) Water is a biological marvel. Its wide range of properties makes it essential for many reactions in Biology. Firstly, water produces the phenomenon known as 'surface tension'. This is when the molecules of water at the surface are held together making a surface strong enough for some organisms to 'walk on water'. This happens because the hydrogen atoms are slightly ?+ whereas the oxygen atoms are slightly ?-. Lots of these water molecules together mean that there is a slight intermolecular attraction, because the slightly negative oxygen is attracted towards the slightly positive hydrogen. ...read more.


Jesus Christ lizard because of its ability to race across the surface of water: Another biological property of water is the fact that it has a high heat capacity. This means that it requires a large increase in energy for a small increase in temperature, making it brilliant for sweating. This is because the body is able to take away the excess heat from the body, as well as minimising the amount of water lost, an essential job for most organisms. Furthermore, water is known as a universal solvent, which means it is able to dissolve many solutes. ...read more.


The polarity of this arrangement causes a weak attraction, breaking the ionic bonds of calcium carbonate and causing the ions to 'stick' to the water molecules, hence dissolving the CaCO3 compound. Dissolving covalent compounds, such as fructose (fruit sugar) is more difficult. However, this is achieved by the ?+ charges of water attracting the OH- groups of fructose. The large surface area to volume ratio means that there are a lot of OH- groups on the surface and so can allow the water molecules to surround it. Despite water being able to dissolve covalent bonds, nevertheless it is more effective of dissolving ionic and polar compounds, simply because of the dipolar arrangements of oxygen and hydrogen. ?? ?? ?? ?? Osama Hamid L2 ...read more.

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Here's what a star student thought of this essay

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Response to the question

This essay has no clear introduction, the candidate just starts listing various information about water. An introduction should set out what you plan to discuss, it also gives you a chance to catch the readers attention. In addition the candidates ...

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Response to the question

This essay has no clear introduction, the candidate just starts listing various information about water. An introduction should set out what you plan to discuss, it also gives you a chance to catch the readers attention. In addition the candidates response to the question is a little weak, this could be improved by providing more answers to the set question and making sure that for each reason given, the importance of water is stated.

Level of analysis

The candidate gives some suitable suggestions to the importance of water, though only briefly and I feel they have missed some key ideas. Such as hydrolysis which is the splitting of a molecule with the addition of water, this is an important biological function. Also they have failed to mention osmosis and most essentially the fact that humans and many other animals rely on water to keep hydrated, we need it for survival. In addition the candidate mentions the chemical importance of water, though this is interesting, they are meant to be discussing the biological importance, therefore in this case the detail given isn’t necessary and is a little more complex than needed. To obtain a higher grade, it is often necessary to undergo independent research, this shows an interest in the subject you’re writing about and can make the essay more enjoyable to read. Finally there is no real conclusion to this essay. A conclusion should summarise your key points and ideas (in this case the main reasons why water is important in biology). This brings the essay to a close and gives you a chance to leave the reader with a good impression.

Quality of writing

The points that the candidate has discussed are scientifically accurate, though their language is fairly simple and for this level of qualification I would expect to see topics discussed using scientific terminology. On a positive note the candidate has a good vocabulary and there doesn't appear to be any issue with selling, grammar or punctuation. Overall this is an average piece of work as the candidate hasn’t fully explored the question, therefore I would expect this to achieve a D/C grade.

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