Biology
Name:
Liver Enzyme Lab
Standard 1
Purpose: Investigate some factors that may affect the activity of enzymes.
Hydrogen peroxide (H2O2) is a toxic substance to our cells. It is a by-product of energy
conversion in our bodies and must be broken down before it accumulates to lethal levels.
Catalase is an enzyme in our cells that breaks down hydrogen peroxide. This reaction
occurs thousands of times each second! Bubbles are released when the hydrogen peroxide
is breaking down. Heat is also released in this reaction. When heat is released in a reaction
it is called exothermic. When heat is required for a reaction to take place it is called
endothermic.
PRE-LAB: Use the paragraph above, your textbook, and/or a dictionary to answer the
following questions.
1) Briefly discuss what an enzyme is.
Sentence Starter: An enzyme is...
2) What is a chemical reaction? What is the chemical reaction that will take place during
this lab?
Sentence Starter: The purpose of this reaction is to...
3) What is the function of our liver?
Sentence Starter: The function of our liver is to…
4) What is a substrate ?
Sentence Starter: A substrate is…
5) How do we get hydrogen peroxide in our cells?
Sentence Starter: Hydrogen peroxide is in our cells because...
6) What is an acid? What is a base?
Sentence Starter: An acid is…
7) Explain how we measure the strength of acids and bases? Be detailed in your answer.
Sentence Starter: We measure the strength of acids and bases using…
PROCEDURE and Data:
Part 1: Do animal cells have enzymes to break down hydrogen peroxide?
Add a few drops of hydrogen peroxide to one of the wells with liver. Observe what
happens. Record your observations in the data table.
Part 2: Does salt affect enzyme activity?
Add a small scoop of salt to one of the wells with liver. Then add a few drops of hydrogen
peroxide. Record your observations in the data table.
Part 3: Does acid affect enzyme activity?
Add a few drops of vinegar to one of the wells with liver. Then add a few drops of
hydrogen peroxide. Record your observations in the data table.
Part 4: Does base affect enzyme activity?
Add a small scoop of baking soda to one of the wells with liver. Then add a few drops of
hydrogen peroxide. Record your observations in the data table.
Part 5: Does cold affect enzyme activity?
Obtain one piece of chicken liver that is on ice. Place it in one of the wells. Then add a
few drops of hydrogen peroxide. Record your observations in the data table.
Part 6: Does heat affect enzyme activity?
Obtain one piece of cooked chicken liver. Place it in one of the wells. Then add a few
drops of hydrogen peroxide. Record your observations in the data table.
Results of Enzyme Tests
Part:
Observations, Results:
1) Liver
2) Liver and Salt
3) Liver and Acid
(Vinegar)
4) Liver and Base
(Baking Soda)
5) Iced Liver
6) Cooked Liver
Questions for Discussion:
1) What are the control variables in this experiment?
Sentence Starter: Control variables include…
2) What is the dependent variable in this experiment? What makes this the dependent
variable?
Sentence Starter: The dependent variable is...
3) How did temperature affect the enzyme activity? Use your data to support your
answer.
Sentence Starter: According to my data…
4) How did pH affect the enzyme activity? Use your data to support your answer.
Sentence Starter: According to my data…
5) How did the salt affect the enzyme activity? Use your data to support your answer.
Sentence Starter: According to my data…
6) What questions do you now have about enzymes? Try to think of at least 3.
Sentence Starter: Questions I now have about enzymes are...
Don’t forget to write a conclusion. Remember your conclusion should be at least 3-4
sentences long and
1) Restate the purpose
2) Explain (using DATA) how you did or did not meet the purpose