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To investigate the effect of changing the total surface area of a potato containing catalase, on the enzyme activity when hydrogen peroxide is added.

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Aim To investigate the effect of changing the total surface area of a potato containing catalase, on the enzyme activity when hydrogen peroxide is added. Background Information An enzyme is a biological catalyst, which is present in potatoes. Hydrogen peroxide is produced in all living cells. If it builds up, it is toxic and so it must be broken down in order to prevent this. Catalase is an enzyme found in all living cells. It speeds up the breakdown of hydrogen peroxide into two harmless substances, water and oxygen. The enzyme that I am using, catalase, is found in potatoes. It exists inside the cells and is released when the potato is cut open. Because it is from the potato, it is normally in a cold place when the potato is growing. Correcting pH or temperature imbalances will usually allow the enzyme to resume its original shape or conformation. Some substances when added to the system will irreversibly break bonds disrupting the primary structure so that the enzyme is inhibited permanently. ...read more.


6. After 5 minutes, record volume of oxygen, which has been produced. 7. Repeat experiment with the same sized piece of potato cut up into different numbers of pieces. Preliminary Experiments We conducted some preliminary experiments to distinguish the exact amount of hydrogen peroxide needed to ensure that the experiment was successful and that the reaction took part within the allotted 5-minute period. We found that this amount, after several attempt with other volumes, was 25cm�. Fairness To make it a fair investigation I will have only one variable, the number of pieces the potato is cut into. Room temperature will be kept the same although since we cannot control this, we will record any changes that may occur and take them into account when considering the conclusion. If the room temperature were to rise, it would affect the overall result. Before cutting the pieces up, we will insure that it begins sized 4cm by 1cm by 1cm. ...read more.


I had six results, which was just enough to support my conclusions, I would have done more to ensure that I had reliable results, but there was not enough time to do more tests, accurately. If I were to do the experiment again I would measure the potato pieces using a micrometer, which would provide far more accurately sized pieces and mean a much more accurate set of results. Also it would have been more accurate if I had someone to start the clock as it is difficult to mix the solutions and start the clock at the same time. To make the experiment more accurate I would have repeated the tests 3 times to make my results more reliable. My test was fair as I ensured that all the variables except the number of pieces of potato were kept constant for all the tests that I did. ?? ?? ?? ?? Heather R Davies 11MDM Biology Coursework 2000/2001 Investigating Enzymes C:\Documents and Settings\ckd\My Documents\essays\doc\after\1936.doc ...read more.

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