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4.2 plan and perform a first-hand investigation to test the conditions that influence the rate of enzyme activity
plan and perform a first-hand investigation to test the conditions that influence the rate of enzyme activity
- To be able to plan your investigation you will need to decide which enzyme to use. The enzyme catalase breaks hydrogen peroxide into water and oxygen. The following experiment is a fairly simple one that shows the effect of pH on the action of an enzyme. Whether you do this investigation or another one you will need to decide which variables will be kept constant. In this investigation the variables that are kept constant are the test tubes, the amount and concentration of hydrogen peroxide solution and the size of the piece of liver put into each test tube. Other environmental conditions such as temperature, the amount of light and humidity are also kept constant. Therefore the only variable that is changed is the pH. Any differences between the test tubes could be accounted for by the differences in pH if all other variable are kept constant.
The effect of pH on catalase
Aim : To examine the rate of reaction of the enzyme catalase at different pH levels.
Method: Fill six identical test tubes with 20mL of 10% hydrogen peroxide solution. The pH of each test tube is then adjusted by adding drops of sulfuric acid or sodium hydroxide solution. A pH meter is used to monitor the pH so that there is a range from pH 1 to pH 11. To supply the enzyme catalase, equal pieces of liver is placed into each test tube. The rate of reaction is then measured by the height of oxygen bubbles produced.
Results: Catalase was most effective at a pH of 7. At pH 1 and pH 11 the reaction came to a stop.
Conclusion: The enzyme catalase is most effective at pH 7 and then the rate of reaction decreases as the pH increase or decreases from that point.
- This investigation involved the use of some caustic chemicals such as sulfuric acid and sodium hydroxide. Safe work practices must be maintained. This would include protective equipment such as rubber gloves and safety goggles should be worn. Covered shoes should also be worn to protect against spillage.
- Perform your investigation keeping the issues listed above in mind.