This document describes an experiment investigating factors that influence the rate of a chemical reaction catalyzed by the enzyme catalase. Students tested the effect of grinding liver tissue, as well as heating liver tissue to boiling, on the rate of hydrogen peroxide breakdown. Grinding liver tissue increased the rate of reaction compared to using intact tissue. Boiling liver tissue decreased its catalytic activity, likely by denaturing the catalase enzyme.

1. VCE Biology
2011
Unit 1
Outcome 1
Activity of an Enzyme
INTRODUCTION
Enzymes are some of the most important kinds of molecules found in living cells.
Cells could not function without enzymes. They control the chemical reactions of
the cells.
The intracellular enzyme catalase is found in many plant and animal tissues. It
controls the breakdown of hydrogen peroxide into water and oxygen.
2H2O2 catalase 2H2O + O2
Hydrogen peroxide is continually formed by all living cells as a by product of
various chemical reactions. It is toxic to cells if allowed to accumulate, so it is
converted into two harmless substances: water and oxygen.
In this activity, an assessment will be made of the rate at which catalase in liver
cells breaks down hydrogen peroxide to water and oxygen. This assessment can
be qualitative (ie. based on observation) or quantitative (ie. based on
measurement). Decide now on how you will assess the rate of reaction. Eg. +++
= significant reaction or height in cm of solution in test tube indicates rate of
reaction.
/home/pptfactory/temp/20110903093107/enzymeactivity-110903043103-phpapp01.doc

2. AIM To investigate some of the factors that influence the rate of a chemical
reaction catalysed by an enzyme.
MATERIALS
(per pair of students)
• 4 Clean test tubes
• Test tube rack
• Test tube holder
• Bunsen burner
• Matches
• Heat proof mat
• Tripod stand
• Mortar and pestle
• Fresh 6% hydrogen peroxide solution
• Distilled water
• 250 ml beaker
• Glass marking pens
• Forceps
• Spatula
• Wooden splints
• Fine, washed sand (approx. 2g)
• Fresh liver
METHOD
Part A. Whole Liver versus Ground Liver
1. Pour hydrogen peroxide to a depth of about 2 cm into each of the test
tubes. CAUTION: Hydrogen peroxide is corrosive and may burn your skin
and clothing. Take care when handling it.
2. Label the test tubes A to D.
3. Using a mortar and pestle, grind a small piece of liver (approximately 3
cm3) with a small quantity of sand until the tissue is completely macerated.
4. To test tube A add a spatula of fine sand. Cover the top of the test tube
and shake the mixture.
5. After 30 seconds, test the gas above the solution with a glowing splint. (If
it re-ignites oxygen is present.) Record evidence of oxygen and rate of
reaction in results Table 1.
6. To test tube B add a small cube of liver (approximately 1 cm 3).
7. After 30 seconds, test the gas above the solution with a glowing splint.
Record evidence of oxygen and rate of reaction in results Table 1.
8. To test tube C add the ground liver. (You will need to scrape as much as
possible from the mortar so that the quantity is as close as possible to that
in test tube B.)
9. After 30 seconds, test the gas above the solution with a glowing splint.
Record evidence of oxygen and rate of reaction in results Table 1.

3. Part B. Effect of Temperature
1. Heat some distilled water in a beaker until boiling.
2. Place a small piece of liver (approximately 1 cm3) into the beaker of boiling
water.
3. Boil for 4 minutes.
4. Use forceps to remove the liver and allow it to cool.
5. Add the cooled boiled liver to test tube D.
6. After 30 seconds, test the gas above the solution with a glowing splint.
Record evidence of oxygen and rate of reaction in results Table 1.
RESULTS
Parts A & B
Table 1.
Test Tube A Test Tube B Test Tube C Test Tube D
Evidence of
Oxygen
Rate of
Reaction
2 marks

4. Questions
1. What was the control in Part A of this experiment? Explain the purpose of
the control. 1 mark
2. What was the control for Part B in this experiment? Explain the purpose of
the control. 1 mark
3. State one hypothesis this experiment may have been testing.1 mark
4. a) What conclusion can you draw from your results about the effect
grinding has on catalase activity? 1 mark
b) Suggest a reason for these results (Test tube C) 1 mark
5. Suggest what has happened to the enzyme molecule in Part B of this
experiment (Test tube D) 2 marks
6. One group of students recorded some breakdown of hydrogen peroxide in
the sample using boiled liver. Suggest a possible explanation for this
result. 1 mark