Catalase Investigation - Core practical

• The time for each reaction – we used a stopwatch to time each reaction to 3 minutes. If we didn’t control this, each experiment would be different because they would have more time to react.
• The volume of Hydrogen Peroxide used – we used a measuring cylinder to measure 5ml of Hydrogen Peroxide. If we didn’t control this, more substrate would change the saturation point of each experiment making the results different.
• The pH of the reaction – we added a buffer solution to the substrate so the pH would not change. If we didn’t control this, the pH may have changed to increase the rate of reaction.
• The Concentration of Hydrogen Peroxide used – we used the same bottle of hydrogen peroxide which was 20vol in concentration. If we didn’t control this, there would be more substrate molecules which would change the saturation point of each experiment making the results different.
• The type of enzyme and substrate – we used the same enzyme (Catalase) and substrate (H2O2) so the reaction would be the same. If we didn’t control this, different enzymes would have different rates of reaction.
• The source of the enzyme – we used the same potato because different potatoes may have more enzymes due to age. If we didn’t control this, the results would be unreliable because the amount of enzyme would vary.
• The size of potato discs used – we used a cork borer and ruler to measure 2mm thick potato discs. If we didn’t control this, the surface are would vary and more enzyme would react.

Table of Results

Evaluation of method and equipment

Equipment

Method

There were many ways we could have improved the method, here is a list of these factors:

• Repeated the experiment 3 times for more reliability.
• Do the experiment in a water bath so the temperature does not change during the experiment.
• Have somebody to place the bung on the test tube as soon as the reaction begins.

Conclusion

As predicted in my hypothesis, my conclusion proves that as more potato discs are added, the volume of oxygen produced will increase. The evidence that supports this theory is the scatter graphs and results as they show a positive correlation to the enzyme and the volume of oxygen produced. Catalysts are used to speed up a reaction without being involved in the reaction process. This means that when I add more potato discs, I will speed up the reaction because more enzymes will react with the substrate. The reaction goes to a halt at some point in the results because all of the enzyme molecules have bonded with the substrate.