Science Research Investigation: Enzyme Research Question
Background information:
Enzymes belong to the biological class of compounds called proteins, and they act as catalysts in
biochemical reactions by lowering the activation energy in order to speed up the reaction. Since only the rate
of reaction and not the enzyme molecule itself is affected, the enzyme remains unchanged after the chemical
reaction occurs. For this reason, enzymes in general are reusable.
A major difference between enzymes and other chemical catalysts is that enzymes are specific in
nature. This is determined by the shape of the protein molecule that is originally coded for and dictated by the
organism’s DNA. Most enzymes are globular, held together in their secondary and tertiary structures by intraand intermolecular bonds. On their surface are pockets or clefts, known as active sites. It is at this location
that the substrate molecule binds. In order for the reaction to occur, the substrate must fit precisely into an
active site. Here bonds are broken or formed, resulting in a lowered activation energy for the entire reaction,
and the product(s) is/are formed. Once the product is released from this enzyme-substrate complex, the
enzyme remains unaltered and is ready to repeat the cycle.
Because the shape of both the enzyme and substrate are so specific, factors such as temperature, pH,
heavy metals can alter the active site, denaturing the protein and leaving it unable to catalyze the reaction.
Concept map:
References:
"Enzymes." Chemistry for Biologists. Royal Society of Chemistry. November 2004. Web. 14 July 2014.
Mason, Kenneth A., Jonathan B. Losos, Susan R. Singer, Peter H. Raven, and George B. Johnson.
"Chapter 6.4—Enzymes: Biological Catalysts." Biology. 9th ed. New York N.Y.: McGraw-Hill, 2011.
114-15. Print
Teacher Guidelines
Science Research Investigation: Enzyme Research Question
Preparation of the solutions:
Figure 1: Materials need for making the two enzyme solutions
Liver Solution:

Mass approximately 35 grams of beef or chicken liver on an electronic scale. Place the liver into a
blender. Add enough distilled water to bring the level of the liver and water solution to one liter.
Blend thoroughly. Strain the solution through a mesh strainer into a 1-L Erlenmeyer flask and
label as “Liver Solution.”
Potato Solution:

Mass approximately 35 grams of a peeled, raw potato on an electronic scale. Place the potato
into a blender. Add enough distilled water to bring the level of the potato and water solution to
one liter. Blend thoroughly. Strain the solution through a mesh strainer into a 1-L Erlenmeyer
flask and label as “Potato Solution.”
Hydrogen Peroxide Solution:

Obtain 500 mL of 3% hydrogen peroxide and dilute it by adding 500 mL of distilled water. Place
solution in a third 1-L Erlenmeyer flask or beaker and label as “1.5% Hydrogen Peroxide.”
Figure 2: Straining the solution
Teacher Hints:
1. The denaturing of catalase in the potato solution can be slowed by placing the solution in an ice
bath. The best way to solve this problem is to prepare the potato solution catalase a day or two in
advance and pour it into ice cube trays. Place one cube in a small beaker for each group. By the
time the group finishes with setting up the experiment the cube containing catalase has melted.
You may want to warn them that the potato solution takes a few seconds to get started.
2. Students should run two or three trials for each solution to become comfortable with the
apparatus.
3. The minimum number of students in each group should be three, with one holding the inverted
graduated cylinder with the tubing inside of it, one mixing the solutions and swirling the
Erlenmeyer flask/tubing apparatus, and another to time the reaction by watching for the first and
final oxygen bubbles. The reaction will slow down, so the observation of the final bubble will be
approximate. As long as each group is consistent in the collection of the data, the rates should be
similar.
4. As an extension to this initial activity, students can either be divided into groups or select from the
following suggestions to investigate the effect of each of these variables on enzyme activity:
a. Double the enzyme volume
b. Halve the enzyme volume
c. Double the substrate volume
d. Halve the substrate volume
e. Determine the effect of acid and base
f. Change the temperature of the enzyme
Figure 3: Label the solutions
Figure 4: Materials for each station
Name: _____________________________________________________ Date: ___________ Block: _______
Science Research Investigation:
Do plants differ in catalase activity compared to animals?
Introduction to Enzymes:
What would happen to your cells if they made a poisonous chemical? Do you think that your cells
would die? In fact, your cells are always making poisonous chemical. They do not die because your cells use
enzymes to break down these poisonous chemicals into harmless substances. Enzymes are proteins that
speed up the rate of reactions that would otherwise happen more slowly. The enzymes are not altered by the
reaction. You have hundreds of different enzymes in each of your cells. Each of these enzymes is responsible
for one particular reaction that occurs in the cell.
In this lab, you will study an enzyme that is found in the cells of many living tissues. The name of the
enzyme is catalase. Catalase speeds up a reaction, which breaks down hydrogen peroxide (a toxic chemical)
into water and oxygen. This reaction is important to cells because hydrogen peroxide (H2O2) is produced as a
byproduct of many normal cellular reactions. If the cell does not break down the hydrogen peroxide, they
would be poisoned and die. The reaction is written as follows:
2H2O2
2H2O + O2
In this lab, you will study the catalase found in liver and potato cells. You will be using chicken or beef
liver that your teacher purchased in the supermarket. It might seem strange to use dead tissues to study the
function of enzymes. However, is possible because when a cell dies, the enzymes remain intact and active for
several weeks, as long as the tissue is kept refrigerated.
Adapted from: Towle, Albert. "Catalase Laboratory." Modern Biology. Austin: Holt, Rinehart and Winston, 1989. Print.
Prelab Demonstration: What is the purpose of this reaction?
A. Measure approximately 5 mL of the hydrogen peroxide into a clean test tube.

Is the hydrogen peroxide bubbling?
B. Measure 5 mL of liver solution into the other clean test tube. Pour the test tube with the hydrogen peroxide
into the test tube holding the liver solution.

Notice that this reaction produces bubbles. What gas is being released?
C. Recall that a reaction that absorbs heat is endothermic; a reaction that gives off heat is exothermic. Now,
feel the temperature of the test tubes with your hand.

Has the test tube gotten warmer or cooler? Is the reaction endothermic or exothermic?

What do you think is happening in your test tube to cause this reaction to happen?

What is this liquid composed of? What do you think would happen if you added more liver solution to this
liquid?
D. Add another 5 mL of hydrogen peroxide into the test tube holding the liver extract. Clean your station.

Can you observe any reaction? What do you think would happen if you added more hydrogen peroxide to
the remaining liver solution?

Based off your observations, are enzymes reusable? Explain why.
1. Give an overview of the function of an enzyme. Pull in a specific examples of an enzyme (besides
catalase) found in the human body and how it functions.
2. Describe the general structure of an enzyme. List and describe the following parts: amino acids, protein
folding, substrate, product, and active site.
3. Explain hydrogen peroxide and its role in cell health. How is it produced in the body and explain its
purpose and/or lack of purpose.
4. Describe current research that is being done regarding enzymes by using scientific journals, databases
and reliable web references.
Possible Sources:

Chapter 2 Section 4: Enzyme Structure and Function

Video Review: http://www.youtube.com/watch?v=XTUm-75-PL4

Science News: http://www.sciencedaily.com/releases/2008/01/080102134129.htm

Peer Reviewed: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0007589#s4
Guided Inquiry: Does catalases rate of reaction differ in plants and animals?
Materials:
- stop watch
- tubing
- glass dropper tube
- stopper
- (2) 10 mL graduated cylinder
- (1) 100 mL graduated cylinder
- (1) 250 mL flask
- (1) shallow pan for water bath
Enzyme
- (3) 250 mL beakers
- (2) funnels
- Premade solutions of: H2O2, liver,
and potato solution
Substrate
Product(s)
Potato Solution
Liver Solution
Null Hypothesis: There is no significant difference in the rate of reaction (mL/sec) between the
catalase found in the potato (plant) and the catalase found in liver (animal).
Alternate Hypothesis 1: (If/Then/Because): __________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Alternate Hypothesis 2: (If/Then/Because): __________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Fill a container 3/4th full of water and submerge a 100 mL graduated cylinder in the water.
Measure 10 mL of hydrogen peroxide (diluted with water by 50 percent) in a graduated cylinder.
In a second graduated cylinder measure 10 mL of the potato solution.
Place the rubber tubing into the submerged graduated cylinder (keeping the mouth of the graduated
cylinder under the water) invert the cylinder. Make sure the cylinder is full of water (with limited to no air
pockets).
Pour the potato solution into the flask and then add the hydrogen peroxide. Quickly place the stopper on
the flask and gentle swirl.
Begin the timer when the first bubble appears in the cylinder and stop the timer then the bubbles cease.
Collect the amount of water displacement (mL) over time (sec) in the chart below.
Repeat steps 1 through 7 using the liver solution.
Repeat the experiment two times for each solution and share that data with the class.
Figure 1: Materials
Figure 2: Set up of apparatus
Table1: The type of tissues effect on the catalases reaction rate (mL/sec)?
Amount of O2 Produced (mL/sec)
Trial
Catalase found in Potato
Catalase found in Liver
1
2
Your Average:
Class Average:
Line Graph: Include a title; label the x axis and y axis, and make a key that represents the class and your
calculated averages using a bar graph.
Graph 1: _________________________________________________________________________
Possible Research Questions: Concept Map
What variables do you think might be
important in the function of this enzyme?
Open Inquiry: Come up with YOUR OWN catalase based science research investigation.
Assignment: You and your team will design an experiment that investigates one aspect that affects
the enzyme catalases activity. You are allowed to work with up to 3 additional individuals to create a
research investigation. You may turn in one copy of the materials/procedures per group. Your
teacher will meet with each group to quickly to review the materials and procedures and approve your
investigation. Remember that you will be responsible for obtaining any materials that are not
commonly found in the classroom.
Research Question: ________________________________________________________________
________________________________________________________________________________
Null Hypothesis: _________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Alternate Hypothesis 1: (If/Then/Because): ____________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Alternate Hypothesis 2: (If/Then/Because): ____________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
The materials and procedures will be due on: __________________________________
MATERIAL: Your materials list should include the items listed below.
-
Be very specific
-
Do NOT number items
-
Size and number of each item listed
-
All measurements in METRIC units
PROCEDURES: Your procedures should include all of the items listed below.
-
Numbered steps
-
Each action should be written as a different step (Do not write in paragraph form).
-
Write your procedures so that it can be reproduced exactly
-
Be very specific- include equipment used in that step
-
Procedure steps include an exact description of how measurements will be taken
-
Include enough repeat trails (several, one won’t do)
-
Include diagrams if necessary
-
No vague statements
The data collection will be on: _________________________________________________
Please make sure to bring all the material that you will need that day. It will be the only block of class
given to collect the data. The rest will need to be done before or after school based off the teacher
availability.
Name: ___________________________________________________________________ Date: ______________ Block: _________
Design and conduct your own experiment
Research Question: ______________________________________________________________________________
Null Hypothesis: _________________________________________________________________________________
______________________________________________________________________________________________
Alternate Hypothesis 1 (If/Then/Because): __________________________________________________________________________
___________________________________________________________________________________________________________
Alternate Hypothesis 2 (If/Then/Because): __________________________________________________________________________
___________________________________________________________________________________________________________
Independent Variable:
How will you manipulate the independent variable in
each experimental group?
Dependent Variable:
Experimental Group 1:
What are the constants, controlled variables? Quantify these
where possible.
Experimental Group 2:
Constants:
Control Group (if possible):
Data Collection Details:
In the space below, outline the procedure you will use
Dependent Variable:
Number of Trials (provide justification):
Data Analysis:
Another group should be able to replicate it. Include tables, graphs,
or both to displace the data necessary to answer your question.
Result Guidelines: Including summary of data statistical analysis, tables, and graphs
DUE DATE: _________________________________
The results section of your SRP Paper includes the 3 parts listed below:
SUMMARY: The Results section is a Summary of the data/statistical tests in paragraph form and
should include the following items:

Topic Sentence

Identification of variables (IV and DV) and control group (If you had one)

Whether the data (DV) was qualitative or quantitative, explain why.

A description of the statistics performed.
o What tests did you do? T-test, ANOVA, or correlation

State the null hypothesis and whether it was rejected or failed to be rejected based on the
calculated p-value.
Example statements:
o “The means of the experimental groups were significantly different (P<0.05).”
o “There was no statistically significant difference between the means of ____ and
_____ (P>0.05).”
TABLES:

Make a table(s) for your raw data as well as a summary of the statistics done

Columns and rows must be straight and neat (typed).

Headings (with UNITS) are required on all columns and rows.

Titles go above the table, typed in ALL CAPS
Example: TABLE 1: PLANT HEIGHT (cm) VERSUS LIGHT EXPOSURE.
GRAPHS:

Can be either a line graph or a bar graph. Line graphs show trends or relationships. Bar
graphs are used for comparison.

The independent variable goes on the X-axis; the dependent variable goes on the Y-axis.
Label axes with names and units. Include a key.

Titles go below the graph, typed in ALL CAPS
Example: FIGURE 1: PLANT HEIGHT (cm) VERSUS LIGHT EXPOSURE
Discussion Outline:

What was the purpose/significance of the experiment?

With supporting evidence from your data, explain if your null hypothesis was rejected or failed to
be rejected by using your p-value as well as additional descriptive statistics and experimental
observations.
Example:

“The means of the experimental groups were significantly different (P<0.05).”

“There was no statistically significant difference between the means of ___ & ___
(P>0.05).”

If the null hypothesis was rejected, explain how alternate hypothesis (es) may possibly explain this
statistical difference in the experimental groups.

Give Evidence for the claim (refer to the data and statistical tests). This is an important
explanation and the main purpose of the conclusion. Explain how the data support the claim.
Never leave it up to your reader to draw connections. Tell us the science behind why the
independent variables had this effect (or lack thereof) on the dependent variables.

Explain unusual results and/or possible errors in procedures and/or limitations of the experiment.
Talk about possible improvements based off the procedures your group created. What worked
and what didn’t work.

Further research questions that you could possible test later this year. These questions should be
based off what you learned and the content covered.
Reference in MLA/APA format
Include 2 sources other than your lab sheets and textbook must be cited in APA format. Use citation
machine at: http://owl.english.purdue.edu/owl/resources/560/07/
Name: __________________________________________________ Block _________ Date: ____________
Science Research Investigation: Using Sample Data
Do plants differ in catalase activity compared to animals?
Null Hypothesis: There is no significant difference in the rate of reaction (mL/sec) between the
catalase found in the potato (plant) and the catalase found in liver (animal).
Alternate Hypothesis 1: (If/Then/Because): __________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Alternate Hypothesis 2: (If/Then/Because): __________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Practice Data Set: Does catalases rate of reaction differ in plants and animals?
Table 1: ________________________________________________________________________
Catalase Solution
Liver
Volume displaced
Time
(mL)
(sec)
35
32
36
40
41
40
41
23
46
45
Rate
(mL/sec)
Potato
Volume displaced
Time
(mL)
(sec)
4.5
5.9
4.9
4
9
7.8
8.5
6.5
3.4
3.1
4
7
5
6
5
6
7
6
5
5
Rate
(mL/sec)
14.9
26.7
22.1
29.6
26.8
32.1
32.9
33.4
32.7
31.5
Table 2: ________________________________________________________________________
Rate of Reaction (mL/sec)
Descriptive Statistics
Mean
Median
Mode
Max
Min
Range
Sample Size
Standard Deviation
Results of T-Test
Liver Solution
Potato Solution
Graph:
With the data provided create a box and whisker plot in the space provided.
Discussion:
With the data provided write a conclusion in the space provided.