Potato and Catalase Investigation

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Investigate the effect the enzyme found in Potato has on Hydrogen Peroxide.

Prediction and Scientific Knowledge

Potato contains an enzyme called Catalase.  This breaks down the hydrogen peroxide, and oxygen and water are released.  The more potato added, therefore more catalase, the more oxygen and water are released.  This will be true until all the hydrogen peroxide has been broken down.  So as more potato discs are added, the reactions will become more violent and more oxygen will be released.

The enzyme found in potato is Catalase.  This is found in virtually all living tissues.  It catalyses the breakdown of Hydrogen Peroxide.  This reaction releases oxygen and water because:

HYDROGEN PEROXIDE  WATER + OXYGEN

If hydrogen peroxide was left in a beaker or exposed to air, it would take days or weeks even to decompose.  By adding the potato, we are speeding up the decomposition process.  The best way to explain this is the Lock and Key hypothesis.  It is thought that each enzyme has a place somewhere on the molecule called and active site.  The reacting chemicals fit into this site and they react with each other momentarily, and the molecule strand is broken.

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By this process the bonds in the molecule are broken, so this proves that enzymes catalyse decomposition.  Enzymes are specific in their actions meaning that the active site is just the right shape for a specific molecule strand. A protease enzyme will only work on protein, it can’t work on fat. Enzymes wouldn’t work if they had been denatured by exposure to extremes of heat, or strong acids/alkalie.  Denaturing is when the active sites of enzymes are changed so they don’t fit into the molecule strand.

Apparatus

To complete this experiment, I am going to need:

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Minor grammatical errors in places. Otherwise, spelling, grammar and punctuation are okay. The candidate does not include their results or the graphs they mention which may make it hard for other readers to follow their experiment as a model for what they should be getting.

The prediction and scientific explanation are correct but the science is quite hard to follow due to the fact that the candidate is not clear in each statement they make about the role of catalase. I was not sure where hydrogen peroxide came in their experiment at first this confuses most of the earlier prediction statements until their equation. Rather than writing the equation out in words to be more accurate this should be written out with correct scientific state symbols and notation. The candidate should explain why they kept certain factors constant to show greater scientific understanding. The candidate does not think of very thorough improvements and this should be done to show an understanding of why the experiment had some anomalous results and how it could have been made better.

Overall an okay experiment with basic scientific knowledge expected for GCSE employed to create an experiment. The conclusion is adequate as it analyses the results accurately to get a picture of how the experiment went and tries to make some suggestions for improvement. The candidate lacks results in this example.