The general trend shown by the graph is a positive correlation. As the temperature increases from 0-60° the rate of reaction also increases. The graph shows this as the values increase along with the temperature. However, it doesn’t show the optimum temperature or where the rate starts to drop, hence my prediction isn’t completely proved accurate.
To make the mean more reliable, we repeated the experiment. This means I can be more confident in the results that I have obtained. Additionally, I have plotted range bars on my graph to show the spread of data. The range bars are actually fairly spaced apart, which means that the mean may not be as reliable as it could be.
The graph shows that my results are fairly accurate as the mean is reliable and hence the data I obtained is more accurate. However, as the error bars are fairly wide, it could mean that the value I got for the mean is not quite as close to the true value as it could be.
If I were to repeat this experiment, there are certain things that I would adjust to get more accurate results. The first improvement would be to repeat the experiment several times. I did already repeat it for a second time, and as a class we got at least 4 readings for each temperature. However it can be seen that the results are not vey consistent as the range bars are quite big. Hence, to improve I would repeat each temperature around 7 or 8 times, to get a more reliable mean.
Secondly, to improve I would also test the experiment using temperatures higher than 60° to find out the optimum temperature for catalase, and see if the rate starts to drop when the enzymes become denatured. The additional temperatures that I would use would be 65°, 70°, 75°, 80°, 85° and 90°. I would go up in 5 degrees instead of 10 because then the value for the optimum temperature will be more accurate and closer to the true value.
Explanation of Results
Hydrogen peroxide is a toxic by-product of metabolism in organisms. It takes a very long time to decompose; therefore, catalase is used to speed up the breakdown in order to prevent the hydrogen peroxide molecules from intoxicating cells. Catalase in a natural enzyme found in potato cells and is one of the fastest acting enzymes known. Enzmes catalyses a reaction by lowering the activation energy and providing an alternative route. The reaction an enzyme speeds up is either catabolic or anabolic reaction. In a catabolic reaction, substrates enter the active site and are broken into new molecules. In an anabolic reaction separate molecules enter the active site and get chemically joined together. In this experiment, the breakdown of hydrogen peroxide is a catabolic reaction. We know this because it is a larger molecule which has broken down into water and oxygen.
The catalase helps the reaction of breaking down hydrogen peroxide because of the ‘lock-and-key’ method. This means that the shape of its active site is complementary to the shape of the H202 molecule. Below is the equation for the decomposition of hydrogen peroxide
H202 H2O + O2
The graph shows in an increase in the rate of reaction as the temperature increases from 30-60. The reason for this increase is because as the temperature increase, the solution gets hotter, which means that the particles inside start to vibrate more. This means that the substrates and enzymes have more successful collisions as there is more contact between the hydrogen peroxide molecules and the catalase active sites. This results in an increase of rate of reaction as the enzymes-substrate complexes are forming quicker.
Another factor to take into account is that the reaction between catalase and