Enzymes are very important because without them some reactions could not take place and we would not be able to survive. An enzyme is a protein and is also known as a catalyst, each enzyme is specific which means that only the right shape and size of a chemical molecule will be able to fit in and be able to let the enzyme help with the reaction. This is also known as lock and key, as because they must be the right shape and size other wise the enzyme cannot take control of the molecule and help it to change into something else.
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Method
Prior the experiment a list of apparatus was composed. It contained one set of Cork Borer, two glass gas syringe, one stop watch, one test tube rack, four clamp stands, one bottle of Hydrogen Peroxide and one potato, eight test tubes, one measuring syringe, one scalpel and one cutting tile.
The experiment was set up like this:
Each 5-centimetre strip of potato, which was cut with the borer, was cut into firstly two parts secondly three, thirdly four and so on. This was because the surface area was being tested. The cut up pieces were then placed in a test tube with Hydrogen peroxide. The test tube was connected to the gas cylinder and as gas was being released from the solution in the test tube it was possible to measure the amount of gas given off. This was done every 60 seconds to see how much it increased by. These results were recorded by hand on paper.
Analysis and Evaluation
The results show an increase of oxygen every 60 seconds. This increase is by about 1 or 2 sometimes 3 cm3 per 60 seconds. This reflects on the graph as when a line of best fit is shown there is a straight shallow line increasing steadily as the surface area increases. This agrees with my hypothesis. As the surface area increases the more molecules of hydrogen peroxide can come into contact with the surface of the potato and therefore the more pieces of potato added to the hydrogen peroxide the faster the reaction will be and there for more oxygen will be released in a shorter space of time. The results are in my opinion very accurate as the experiment was repeated four times. The only minute inaccuracy in the measurements was the size of the potato chips measured only by a standard ruler.
The experiment on the whole went well. The only variable was the amount of potato chips and this was controlled well as it is quite simple to maintain. The measurements however might have been slightly off because there is always the question of human error and vision impairment and measurements may not have been as accurate as they could have been, but in the conditions the best was achieved.
Looking back on the experiment I believe that there are many ways to improve it. One being the accuracy of the measuring of the chips. An electronic ruler that has a digital screen could have done this. It shows the length up to 3 decimal places, but this piece of equipment is too expensive and only basic measuring equipment was available. This would have made every potato chip used a very accurate length and thickness by using the same cork bora and so ensuring reliability. Measuring the oxygen produced was a little harder, to measure this it may include equipment that is not available and so cannot be carried out. All that is best is that the same person reads it off just in case someone else’s vision is not as good. There was also an obstruction on the reading off of the amount of oxygen. This was a plastic holder used to secure the measuring cylinder to the clamps (pointed out on the diagram) which obscured some of the units and it was difficult to see the exact position of the oxygen and therefore an educated guess was sometimes needed to complete the results. This however has not seemed to be much of a problem as it has not created any anomalies as the graph shows. Also there was a limited amount of time to complete the experiment and I feel more accurate results could have been obtained if more time was given.
If I were to repeat this experiment the following changes would have been made. Firstly I would invest in more accurate equipment to get the results as clear as possible. Secondly more time would be made available, as the potato chips, if left, seemed to go on for a much longer period of time then the time available during the experiment and thirdly if enough time was given I would investigate the experiment further by adding more variables for example varying the temperature to see if it would speed up or slow down the reaction.
Conclusion
The experiment was a success as the results obtained were enough to prove my hypothesis and prove that the greater the surface area the more oxygen is released. This also proves how enzymes work as a catalyst and the more of the potato introduced the faster the reaction takes place. As any reaction the more of a catalyst you introduce the faster the result.
I therefore conclude that the experiment has successfully completed my aim showing everything the practical was carried out for.