Write a background statement about enzymes based on our discussions, reading, and worksheet.
Read the introduction, procedure steps 1-5 and study the materials. Answer the following questions.
1. What's the substrate?
2. What are the the products of the reaction?
3. Where is the catalase?
4. What are the variables in this experiment? List them.
a.
b.
c.
d.
e.
Explain why heat is not a variable. If you were studying the effects of temperature, what other steps would have been added to the procedure.
5. What is/are the constant(s)?
6. What is the control that you should include in the procedure? Be sure to add it in.
List how much of which substances you will put in a test tube to act as a control.
7. Design the data table based on the variables being studied.
8. State the purpose of this experiment.
9. Make a hypothesis for each variable studied.
10. Does your body contain catalase? Explain your reasoning.
11. Write the balanced chemical reaction.
Procedure:
- Arrange the test tubes in the rack and number them for identification.
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Pour 2 ml hydrogen peroxide (H2O2) solution into each of the tubes. After each of the following steps, record your observations. Compare observations on different tubes frequently.
- Using forceps, select a small piece of fresh liver and drop it into a test tube. Be sure to record the test tube number, contents, and the results in your data table.
- Place another piece of fresh liver (the same size) into a mortar. Add a little fine sand and grind the liver. Transfer the resulting mixture to another labeled test tube. Wash the mortar thoroughly.
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Place a 3rd piece of liver in boiling water for a few minutes. Drop the boiled liver into another test tube.
- Using the scalpel (I hope it is clean since the presence of liver could spoil your results.), cut 2 cubes of fresh potato, each the size of the liver used. Place 1 potato cube in a test tube. Be sure that all liver has been cleaned from the scapel and all other materials that are used in this part of the experiment.
- Grind the other potato cube in the mortar (I hope the mortar and pestal are clean so you won't spoil your results.) with sand. Place the potato-sand mixture in a test tube.
Discussion:
- What caused the reaction when you put the liver into the test tubes?
- Explain why there was a difference in the amount of bubbles from the whole piece of liver and the ground liver
- How could you prove that it was not the sand that caused the reaction but the liver or potato?
- How do you explain the difference in activity resulting from the boiled liver?
- What evidence do you have either for or against this reason?
6. What do you think would have happened if you had boiled some potato and put it into hydrogen
peroxide?
7. Which of the materials used seems to contain more catalase, potato or liver? Why do you think this?
REMEMBER TO FOLLOW THE FORMAL LAB WRITE-UP GUIDELINES WHEN YOU WRITE YOUR REPORT.
