Number: _______
Name: _______________________________________________________ Date: ______________ Class: _________
Liver Enzyme Lab
Background: All organisms rely on enzymes to catalyze chemical
reactions. An enzyme is a biological catalyst that increases the
rate of chemical reaction by lowering the level of activation
energy necessary to start the reaction. Without enzymes, many
of the chemical reactions that occur within living things would
proceed to slowly to be useful. Enzymes speed up these
reactions by bringing the reactants into close proximity and
facilitating their interaction. Liver contains a specific enzyme
called catalase. When hydrogen peroxide (H2O2) is added to liver, a chemical reaction occurs which results in the
products of oxygen gas (O2) and liquid water (H2O). In this lab you will test the effect of temperature on this enzymatic
reaction. There will be 4 temperatures tested: 0oC, room temperature, 37oC, and 100oC. Predict which reaction will be
the slowest, which will be the fastest, or whether or not you think a reaction will take place. Record your hypothesis on
the following page.
Purpose:
To determine if changes in temperature will have an effect on the activity of an enzyme.
Materials:
Test tubes (8)
Tweezers
250 ml beakers (3)
Hydrogen Peroxide
Test tube rack
Hot plate
Ice
10 ml graduated cylinder or Pipette
Thermometer
Liver
Procedure:
1) Label 4 test tubes 1 through 4 and put a small piece of liver in each tube.
2) Label 4 test tubes P1, P2, P3, and P4 and put 2 mL of hydrogen peroxide into each of these tubes.
3) Combine test tube 2 and P2 and rate this reaction a 4 out of 5 on the data table below.
a. Feel the test tube before and after adding the hydrogen peroxide. Make note and record any noticeable
observations. Record the temperature as the current temperature of the room (ask your teacher).
4) Label 3 Beakers as follows: Cold, Warm, Hot
5) Prepare an ice water bath (OoC) in the beaker labeled cold.
6) Prepare a warm water bath (37oC) in the beaker labeled warm.
7) Prepare a boiling water bath (100oC) in the beaker labeled hot.
8) Place test tubes 1 and P1 into the ice water bath and let it sit in the bath for 5 minutes.
9) Put Test tubes 3 and P3 into the warm water bath and let them sit in the bath for 5 minutes.
10) Put 1 mL of water into test tube 4 and put it in the boiling water for 5 minutes. After 5 min, remove test tube 4
and let it cool for 4 minutes.
11) Combine test tubes 1 and p1 and rate the reaction on a 0 – 5 scale. Record your data on the table below.
12) Combine test tubes 3 and P3 and rate the reaction on a 0 – 5 scale. Record your data in the data table below.
13) Combine test tubes 4 and P4 and rate the reaction on a 0 – 5 scale. Record your data in the data table below.
14) ********** Clean up all materials very well. No liver should be put down the drain. **********
Mr. Martinez. Pre-AP Biology • Silva Health Magnet 2012-2013 • www.meestermartinez.weebly.com
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Number: _______
Name: _______________________________________________________ Date: ______________ Class: _________
Hypothesis: 10 pts__________________________________________________________________________________
As long as they write something about how temperature will affect the enzyme reaction. Example: If I raise the_________
__temperature of the enzyme then the reaction will be stronger or be faster________________________________.
Data/Results: As long as they filled in something logical in each of the slots (Answers may vary). 10 pts total, 2pts ea slot
Test Tube
Temperature
oC
oF
Rating
Comments
(1 2 3 4 5)
(How fast was the reaction, how high did it go, did the tube get warm, etc)
1
0
32
2
22
71.6
4
37
98.6
5
100
212
1
2
3
4
For these they must write something that describes the reaction. Example:
the tube got warm, the tube overflowed, no reaction occurred, etc.
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Construct a line graph based on the data above. Label the horizontal axis temperature and the vertical axis rating.
** Do not forget…tables and graphs need appropriate titles and labels to each part.
10 pts: Graphs may vary, as long as it matches their data they should get credit (most should look similar to this)
Mr. Martinez. Pre-AP Biology • Silva Health Magnet 2012-2013 • www.meestermartinez.weebly.com
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Number: _______
Name: _______________________________________________________ Date: ______________ Class: _________
Discussion:
1) What are the dependent and independent variables in this experiment? _____Independent: Temperature
Dependent: Rate of reaction ____________________________________________________________________
___________________________________________________________________________________________
2) What is the control in this experiment? ____The room temperature tube ________________________________
___________________________________________________________________________________________
3) What are enzymes? What are their roles in chemical reactions? Enzymes are biological catalysts that speed up
chemical reactions ____________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
4) Describe what happened to test tube 2 when hydrogen peroxide was added to the liver. What gas was
produced? What liquid was left behind? _ The enzyme catalase in the liver catalyzed the reaction of hydrogen
peroxide into liquid water and oxygen gas.__2H202 Enzyme  2H20 + O2 ______________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
5) Was the reaction in test tube 2 exothermic (exergonic) or endothermic (endergonic)? Explain how you knew.
__The reaction was exothermic because the reaction released heat. _____________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
6) What factors could have influenced the rating of the chemical reaction between the liver and the hydrogen
peroxide? Give two factors. Explain each. _ • Temperature: The tubes could have cooled or warmed between
steps in the proceudre________________________________________________
• Concentration: The more enzyme (liver) there is the faster the reaction will happen, the less concentration there
is the slower the reaction will happen. ____________________________________________________________
• pH, activators, and inhibitors are also valid answers.________________________________________________
7) What effect does temperature have on the activity level of an enzyme? (Hint: Look at what happened in test
tubes 1 and 4). Enzymes work best at an optimal temperature; temperatures below the optimal temp will slow the
reaction down and temps above the optimal temp will slow the reaction down and eventually denature the enzyme
causing little to no reaction in hotter than optimal temps. _____________________________________________
Mr. Martinez. Pre-AP Biology • Silva Health Magnet 2012-2013 • www.meestermartinez.weebly.com
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