Name: __________________________________
Catalysts and the Control of Biochemical Reactions
Introduction
Catalysts are chemicals that promote chemical reactions in other chemicals but do not become a
part of the product nor do they get used up. Living cells use special catalysts that are complex proteins.
These organic catalysts are called enzymes. Enzymes control cellular chemical reactions. Enzymes are
"substrate specific," meaning that an enzyme will work with the reactants of only one chemical reaction.
In this investigation, you will experiment on both an enzyme and a simple inorganic catalyst.
First you will test the relationship between temperature and reaction rates of an enzyme. The
enzyme is catalase, which is naturally found in cells and is used to break down hydrogen peroxide which
if too concentrated can be toxic to cells. The second experiment will involve just catalase. In this
experiment you will test the relationship between reaction rate and quantity of enzyme.
Hydrogen Peroxide
H2O2  O2 + H20
Read the experimental design and write a hypothesis for each experiment. Remember to include both the
dependent and independent variable.
Experimental Design
Procedure A - Hypothesis:
Obtain two clean cups and add a fresh piece of liver to one and a piece of potato to the other. Add 10
drops of H2O2 and observe. Record the reaction in Data Table 1. These observations will serve as a
control.
Procedure B – Hypothesis:
Obtain two new cups. Place a piece of boiled potato in one cup and a piece of liver in the other cup.
Add 10 drops of H2O2 and observe and record the reaction in Data Table 1.
Procedure C – Hypothesis:
Obtain two new cups. Add to one cup a small piece of potato that has been soaking in lemon juice.
Now add a small piece of liver that has been soaking in lemon juice to the second cup. Add 10 drops
of H2O2 and observe. Record the reaction in Data Table 1.
Procedure D – Hypothesis:
Use two cups. Place a small amount of mashed potato in one cup and mashed liver in the other cup.
Add 10 drops of H2O2 and observe and record the reaction in Data Table 1.
Procedure E – Hypothesis:
Now take the first two cups used in Procedure A and add an additional 10 drops of H2O2 and observe
and record the reaction in Data Table 1.
Name: __________________________________
Data Table 1:
Analysis of Potato Reaction
Analysis of Liver Reaction
Part A: control
Part B: boiling
Part C: lemon juice
Part D: mashing
Part E: revisiting Part A
Analysis
1. Assuming that the breakdown of H2O2 results two substances, it is obvious that one of these is a
gas. What was the gas?
2. The second breakdown product is a harmless liquid. Complete the chemical equation below.
H2O2 ------(catalyst)------> ___________ + ___________
3. How do you think mashing affects the amount of enzyme present?
4. How did the reaction of the boiled materials differ from the others?
5. How did the reaction of the lemon juice soaked materials differ from the others?
Conclusions
1. What can you conclude about catalytic reactions and temperature?
2. What can you conclude about the reaction rate and the amount of enzyme used?
3. What reaction did you get when you performed experiment E? Did you expect to see this? Why
or why not? What does this tell you about enzymes?
4. What does conclusion #1 imply about why people die when infection causes extreme fever?