Osama Hamid L2
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 δ+ whereas the oxygen atoms are slightly δ-. 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. This results in a hydrogen or H-bond, although technically speaking it is not actually a bond, just an attraction. As these molecules move around, the H-bonds continuously break and reform with other molecules. Although individually, these bonds are weak, the collective action of breaking and reforming means that together, the force is very strong. An example of an organism relying on the concept of surface tension is the basilisk lizard, also known as the Jesus Christ lizard because of its ability to race across the surface of water:
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Peer Reviews
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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.
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.
Response to 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.
