Introduction
1. Why do cells have catalase?
2. What kind of biomolecule are enzymes?
3. What does it mean that enzymes are catalysts?
4. How do we know just from the name that catalase is an enzyme?
5. True or False: Most enzymes are generalists and can act on multiple different substrates.
6. List three factors that influence the activity of an enzyme.
7. Describe two different ways temperature can affect enzyme activity.
8. Is yeast alive?
Part 2: Testing the Enzyme
1. What is the enzyme in this experiment? What is the substrate?
2. If the enzyme is functioning, what gas will be produced?
3. Did you observe a difference in the amount of reaction between the cups? If so, what caused the difference?
4. Insert a picture of your cups (Step 7):
5. Does the amount of hydrogen peroxide affect the rate and amount of reaction? Explain.
6. What role is the dish soap serving in this experiment?
7. What happened when you added hydrogen peroxide to Cup 1? Explain why this happened.
Part 3: Effects of Temperature on Enzyme Activity
1. Record your hypothesis for this experiment prior to beginning any of the tests.
Cold. 50*F, Room Temperature 80*, Hot 120* F
Table 1 – Temperature Effects on Enzyme Reaction Measured in Foam Height (cm)
| Cold | Room Temperature | Hot |
Yeast Temperature |
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20 seconds |
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40 seconds |
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60 seconds |
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120 seconds |
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4 minutes |
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2. Did you get a reaction from the cold yeast? If so, how did it compare to the room temperature yeast? If not, what do you think caused this?
3. If you had allowed the yeast to freeze and then thawed them prior to the start of the experiment, do you think you would have observed a reaction?
4. Did you get a reaction from the hot yeast? If so, how did it compare to the room temperature yeast? If not, what do you think happened?
5. Insert a picture of your experimental cups (Step 8):
6. How does the temperature affect enzyme function? Use evidence from your data to support your answer.
7. Is it possible to heat the yeast up too much? What would you expect the reaction to look like if the yeast were exposed to higher temperatures?
8. Did you notice any changes in the amount of foam produced (other than settling) after 4 minutes had elapsed? Why do you think this happened?
9. Would you expect the same results if you cooled/warmed the hydrogen peroxide instead of the yeast? Explain.
10. Do you think there is an optimal temperature for catalase – a temperature where it is most effective? If so, what do you think it might be?
Part 4: What Else has Catalase?
1. Record your hypothesis for each test solution describing what you predict the reaction will look like prior to beginning any of the experiments.
Table 1 – Testing Unknowns for Enzyme Reaction Measured in Foam Height (cm)
| Vegetable | Fruit Juice | Saliva |
Vegetable/Fruit Used |
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20 seconds |
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40 seconds |
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60 seconds |
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120 seconds |
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2. Did any of the substances you tested contain catalase?
3. Did any of the results surprise you, either by having or not having catalase or rate of the reaction?
4. Are there other substances that you would like to test?
5. What is the independent variable in this experiment? What is the dependent variable?
6. If you had the saliva at 37˚C (body temperature) do you think you would see a difference in the type of reaction compared to what you observed? Why?
7. It has been reported that catalase levels in saliva increase with stress and activity levels. Why do you think that would be the case?
8. In general, thinking back to all parts of this lab, what worked well in this experiment? What didn’t? Why?
