Biology
Name:
Liver and Potato Enzyme Lab
Purpose: Determine if both plant and animal cells have enzymes to break down
hydrogen peroxide. Investigate some factors that may affect the activity of
enzymes.
Background Questions: Read the paragraph below and then answer the
questions:
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. The reaction that is used to
break down the hydrogen peroxide is: 2H2O2 2H2O + 2O2 + heat
1) Briefly discuss what an enzyme is. Sentence Starter: An enzyme is...
2) What is the purpose of this reaction in the cells of your body?
Sentence Starter: The purpose of this reaction is to...
3) What is the enzyme used in the reaction? Sentence Starter: In this
reaction, the enzyme is...
4) What is the substrate in the reaction? Sentence Starter: In this
reaction, the substrate is...
5) What are the final products of this reaction? Sentence Starter: The
products of this reaction are...
6) What type of reaction is this in terms of heat energy? Sentence
Starter: In terms of heat energy this reaction is...
Procedure and Data: For each part of the experiment you need to copy the
data table into your lab book and summarize the steps you will be completing
during the lab.
Part 1: Do both plant and animal cells have enzymes to break down hydrogen
peroxide?
1) Fill a test tube about ¼ of the way full with hydrogen peroxide.
2) Add a piece of chicken liver to the test tube. Observe what
happens. Record your observations in the data table.
3) Fill another test tube about ¼ of the way full with hydrogen
peroxide.
4) Add a piece of potato to the test tube. Observe what happens.
Record your observation in the data table.
Test for Enzymes
Tube:
Observations:
Liver
Potato
Part 2: How can we determine whether or not enzymes can be re-used?
1) Remove the chicken liver from the test tube. Pour out the hydrogen
peroxide.
2) Fill the test tube about ¼ of the way full with new hydrogen
peroxide.
3) Add the chicken liver to the tube again. Observe what happens and
record your observation in the data table.
4) Remove the potato from the test tube. Pour out the hydrogen
peroxide.
5) Fill the test tube about ¼ of the way full with new hydrogen
peroxide.
6) Add the potato to the test tube again. Observe what happens next
and record your results.
Test for Re-using Enzymes
Tube:
Observations:
Liver
Potato
Part 3: How can we determine if heat denatures an enzyme?
1) Fill the test tube about ¼ of the way full with hydrogen peroxide.
2) Add the heated up chicken liver to the test tube. Observe what
happens and record your results.
Test for Heat
Tube:
Liver
Potato
Observations:
Part 4: How can we determine if cold affects enzyme activity?
1) Fill the test tube about ¼ of the way full with hydrogen peroxide.
2) Add the cooled chicken liver to the test tube. Observe what
happens and record your results.
Test for Cold
Tube:
Observations, Results:
Liver
Potato
Questions for Discussion:
1) Do both plant and animal cells have enzyme to break down hydrogen
peroxide? Explain using your data. Sentence Starter: Plant and
animal cells...
2) Can an enzyme be reused? Explain using your data. Sentence Starter:
An enzyme...
3) Does heat denature enzymes? Explain using your data. Sentence
Starter: Heat...
4) Does the cold denature enzymes? Explain using your data. Sentence
Starter: Cold...
5) How could you test to see if pH affects an enzymes activity? Write
out the steps you would take to answer this question. Sentence
Starter: To test if pH affects an enzymes activity, I would...
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
3) List 2 things you learned from doing this lab