Investigating the effect of pH on catalase activity
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Explainer Video
Summary
Investigating the effect of pH on catalase activity
In a nutshell
There are several factors that affect the activity of enzymes. Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. By using catalase to break down hydrogen peroxide at different temperatures, you will be able to investigate the effect of temperature on enzyme activity.
Equations
The first equation is the word and symbol equation of the breakdown of hydrogen peroxide. The second equation can be used to calculate the rate of reaction after the experiment.
WORD EQUATION | symbol equation |
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Variable definitions
QUANTITY NAME | syMbol | UNIT NAME | UNIT |
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Equipment list
The following equipment list can be used to conduct an experiment to evaluate the effect of temperature on enzyme activity.
EQUIPMENT | USE |
| Water bath | To control the temperature of the boiling tubes. |
| Source of catalase (e.g., potato) | The enzyme that will be used in this practical. |
| Hydrogen peroxide solution | The chemical that will be broken down in this practical. |
| Measuring cylinder | To measure the amount of oxygen produced. |
| Delivery tube | To connect the test tube to the measuring cylinder and prevent oxygen from escaping. |
| Pipette | To put the correct amount of hydrogen peroxide into the boiling tubes. |
| Stopwatch | To measure the time. |
| Thermometer | To measure the temperature. |
Experiment 1: Investigating the effect of temperature on the rate of reaction of catalase enzyme
Experimental variables
The independent variable is the one you change. The dependent variable is the one that depends on what has been changed, therefore it is the one that is measured. The constant variable is one that has been kept constant.
| Independent variable | |
| Dependent variable | |
| Control variable | |
Safety precautions
When carrying out experiments, it is essential to consider safety precautions. This is so you and others do not get hurt.
HAZARD | RISK | SAFETY MEASURE |
| Hydrogen peroxide | Hydrogen peroxide can cause irritation to the eyes and skin. | Make sure to wear eye protection and gloves when handling hydrogen peroxide. |
Method
This is your instructions on how to complete the experiment.
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| 1. | Add a set amount of hydrogen peroxide to a boiling tube using a pipette. Then, put the tube into the water bath at . |
| 2. | Set up the equipment as illustrated in the diagram above. |
| 3. | Add a cube of potato to the test tube and attach the bung to the tube as quickly as you can. Start the timer on the stopwatch. |
| 4. | After one minute has passed, measure how much oxygen has been produced. Record this value and repeat the test three times. |
| 5. | Repeat steps 1-4. Each time, increase the temperature of the water bath (e.g. ). Remember to record all the values in a table. |
Analysis
This is how you can use your data to be able to form conclusions.
| 1. | You will now have a table with a list of temperatures and the volume of oxygen produced by the hydrogen peroxide in a minute. |
| 2. | Calculate the mean volume of oxygen produced at each temperature. |
| 3. | Then, calculate the mean rate of reaction at each temperature. |
| 4. | You should then plot the rate and the temperature onto a graph. The mean rate of reaction should be on the -axis as it is based on the dependent variable. The temperature of the solution should be on the -axis as it is the independent variable. Draw a line through the points on the graph. |
Conclusion
Your graph should show the optimum temperature for catalase enzyme activity. At this temperature, the greatest volume of oxygen will have been produced due to the breakdown of hydrogen peroxide. This is because the enzyme will be the most efficient at this temperature. There will be a gradual loss of enzyme activity away from the optimum temperature, as the active site will become distorted. The graph will also show that, at extreme temperature values furthest from the optimum temperature, there will be no rate of reaction. This is because the catalase enzyme will be completely denatured at these temperatures and be inactive. The shape of the graph should be similar to the graph below.
Evaluation
Once you have completed your experiment, it will be important to consider the quality of your data and how accurate your results are. Identify potential sources of random or systematic error and suggest possible improvements and further investigations.
FAQs - Frequently Asked Questions
What is a control variable in the enzymes and temperature required practical for GCSE biology?
One of the control variables for the enzymes and temperature required practical for GCSE biology the size of the potato pieces.
What is the independent variable for the enzymes and temperature required practical for GCSE biology?
The independent variable for the enzymes and temperature required practical for GCSE biology is the temperature of the water bath.
What is an example of a hazard in the enzymes and temperature required practical for GCSE biology?
One of the hazards in the enzymes and temperature required practical is hydrogen peroxide. Hydrogen peroxide can cause irritation to the eyes and skin. Make sure to wear eye protection and gloves when handling hydrogen peroxide.