Design your own experiment

August 4, 2020
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Experiment #4: Design your own experiment
This is the section of the lab that you will be writing your lab report about. You and yourlab
partners will have to turn in the following:
1) A group work assignment turned in during this lab describing yourmaterials,
procedures, and results(one per group)
2) INDIVIDUAL lab reports describing this experiment (these must bedone
independently)
3) INDIVIDUAL teamwork assessment documents describing how well all the membersof
your group did or did not contribute to the team’s success
Your lab group will need to design an experiment to test EITHER
a) the effect of enzyme concentration on catalase activity or
b) the effect of substrate concentration on catalase activity
Your instructor will tell you which of these you are testing.
Your lab group must create the protocol to test the appropriate variable, including a listof
necessary materials and the steps you followed during theexperiment.
What variable will your group be testing?
1) Brainstorm within your group to determine a rough idea of how you will carry out your
experiment. Describe the general protocol.

2) What materials will be necessary for you to carry out this experiment? Be specific! This
information needs to be included on your lab report.

3) What is the control concentration for your group’s experiment?

4) What other conditions will you test? Your group must test at least three other
concentrations during the experiment (e.g. 1 mL of enzyme and 5 mL of substrate, or5
mL of enzyme and 3 mL of substrate). Be very specific in describing your testtubes.

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Use the space below to list the method you and your group use to carry out theexperiment.
Be VERY specific – you will use this information in writing your lab report. (Use only asmany
steps as are necessary). Check your experimental design with your instructor before
continuing.
Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

Step 6:

Step 7:

Step 8:

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Use this page to record the results of the experiment your group performs. Use only asmany
rows of the table as necessary.
Results of testing for effect of concentration
Tube Amount of
enzyme in mL

Amount of
peroxide in mL

Bubble column
height in mm

Results

1
2
3
4
5
6

Graph your results below. Makes sure to label your graph.

Bubble
column
height
(in mm)

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What effect does variable you tested have on catalase activity?

Do you think it would be possible to have too much of this substance in the tube? Whatwould
happen then?

What do you think would happen in each of the test tubes you tested if the experiment was
allowed to run indefinitely? Would all the test tubes eventually have the same amount of
product?

Experiment #5: Testing liver as a source of catalase

  1. Obtain a piece of liver from the petri dish at the front of the room. Use thetweezers
    provided.
  2. Place the piece of liver in an extra-large test tube.
  3. Add 10 mL of hydrogen peroxide to the test tube. Swirl to mix, and then wait 20
    seconds. Immediately record the height of the bubble column in mm.
    a. If your tube should overflow with bubbles, record the height of the tube asyour
    bubble column height (and clean it up!)
  4. Feel the bottom of the tube.
  5. Record results in the table below.
    Results of testing liver catalase activity
    Tube Contents

Height of
bubble column

Why reaction did or did not
occur

Did the test tube
change temperature?

1

Experimental procedure: testing the reusability of catalase

  1. Was this reaction exergonic or endergonic? Explain your answer.
  2. What enzyme is in the liver?
  3. Develop a hypothesis: at the end of the reaction, is the catalase in the liver cellsstill
    active? Why or why not?

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  1. Describe step-by-step an experiment that you will perform to test yourhypothesis.
  2. Check your experimental design with your instructor, then perform theexperiment
    and record yourresults:
  3. Was your hypothesis correct?

Summary of results: use this table to summarize the results of the experiments that you have
done today.
Summary of Results
Experimental conditions Optimum enzymatic activity Inhibits enzymatic activity

Substrate

Temperature

pH
Enzyme concentration or
Substrate concentration

Post-Lab Cleanup

  1. Wash, rinse thoroughly, and turn test tubes upside down to air dry. All markingsMUST
    be removed from the tubes.
  2. Throw the liver in the trash can.
  3. Turn off the hot plate.
  4. Ethanol the tables and push in the chairs.

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Post-Lab Review Questions

  1. Name the following for the experiments you performed today:
    a. Substrate/reactant
    b. Enzyme_
    c. Products
  2. What does “substrate specificity” mean?
  3. What were the optimum conditions for the enzyme that you studied today?
    a. Temperature
    b. pH
  4. Which conditions denatured the enzyme?
  5. Why was the catalase from the potato cells active at cold temperature? Would ahuman
    enzyme be active at thistemperature?
  6. Would the optimum pH for a stomach enzyme be basic, neutral, or acidic? Explain your
    answer.

References
Brooker, Robert, Eric Widmaier, Linda Graham, and Peter Stiling. (2014). An Introductionto
Energy, Enzymes, and Metabolism. Biology 3
rd
Edition, 118-135.

Hoobler, Cynthia, Karen Duston, Adam Eiler, Jennie Plunkett, Kirsten Raines, andMary
Wisgirda. (2007). Enzymes. General Biology I and II, 57-64.

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Lab Report Materials
General Instructionsfor Writing Lab Reports
Writing a lab report is a standard feature of science lab classes. It will be part of your grade
for each lab practical this semester, because it is the best way to organize all of theinformation
needed to understand the lab procedures and results. A person should be able to read your lab
report and:

• Know exactly how to do this experiment
• Find a table, graph or photo of your results
• Know what you concluded at the end of your experiment
• Know what experiment you would do next to follow up on these results
Science writing is somewhat different from writing for other disciplines. What are the major
differences that you should look outfor?
• The passive voice is used. So instead of writing, “I measured the bone with the meter stick,”
it would be “The bone was measured with a meter stick”. The report is about the work, not
about you.
• Methods and Results should be written in the past tense because these are things that have
already happened.
• Sentences should be as short as possible, and only the most relevant information is
included.
• Direct quotes are never used.
• Everything must be rewritten in your own words. Directly copying (oronly
slightly modifying) someone else’s work (including the work of other students) is plagiarism
and will result in a grade of 0.
The format of a lab report is also different. These are the seven headings that you will use to write
the lab report:
Purpose of this lab: What did you learn from this lab? What did the experiments teach you about
biology? This section should consist of only one or twosentences.
Introduction: This part gives background information about the particularsubject that the lab
covers and the experiment being performed. You will need references for this section.Your
references may NOT include the labmanual.
Materials: The equipment and supplies used should be listed. Specific information should be given
as to amounts, concentrations, and so on. Make sure you include ALL of the materials used in the
procedure outlined in your lab report. Likewise, make sure you include ONLY the materials used in
the procedure outlined in your labreport.
Methods: The write-up of the methods should be similar to a detailed recipe. It must be written in
paragraph form. A person who has never done this lab should be able to read this section and know
exactly what equipment and supplies are needed and how to perform the experiment.

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Results: What was the final outcome of the lab? This will include measurements, illustrations, and
answers to questions on the grading rubric. A person who has never done this lab should be able to
read this section and know exactly what happened in thelab.
Discussion: This section should explain what the results mean. What was learned? Doesthis
outcome make sense, or does it seem unusual? You may be required to answer one or more critical
thinking questions regarding the outcome of the experiment. This section also describes the next
experiment that could be done based on the results seenhere.
References: When you mention someone else’s work, you give them credit for it.References
usually are found in the Introduction and the Discussion section of a report. First, you rewrite it in
your own words (Do not use direct quotes!). Then you insert a citation telling where the
information comes from. The full information about the reference comes at the end of the report.
For example, in one reference you find the sentence “The Metric System was developed in
France under Napoleon in the 1790’s for the purpose of standardization of units as trade expanded
through Europe.” You might rewrite this as: The metric system was implemented as a wayto
standardize units of measurement throughout Europe. It was created in France during the 1790’s
(Hoobler et al, 2007). At the very end of the report, you put the entire reference. There isno
standard scientific format for references, so we are going to use the standard APAformat.
The grading rubric shows you exactly how your professor will grade your report. The
maximum possible number of points that you can earn is broken down by section. As you are
writing your report, you should be using the grading rubric to ensure that you have included
everything that you should be in the report. That is the way to get the highest grade possible.

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Grading rubric, Lab report 2
Lab 9: Enzymes, Experiment #4 –Design your own experiment
Name:
Points
earned

Points
possible

Section

1 Purpose: Objectives of the lab are explained in one or twosentences.
5
Introduction: First paragraph is a description of enzymes: their function in
the cell, what type of molecule they are, how they affect chemical
reactions, and what conditions can affect enzymeactivity

5
Introduction: Describe the experiment done in lab. What was theenzyme,
and what reaction did it catalyze (what were the reactants andproducts)?
What was the source of the enzyme? What variable was tested in the
experiment? What was the control?
2
Materials: All materials used in this experiment are listed, bulleted listis
acceptable.
4
Methods: The procedure is described in paragraph form, written inpast
tense and passive voice
5
Group work complete: Materials, Methods, and Results were turned inby
the group on the day of the lab.
5
Results: Graph made in Excel is used to display the results. It isclearly
labeled.
4 Results: Results are also described in a shortparagraph.
4
Discussion: The results for each condition tested are explained. Which
condition resulted in the mostactivity?
5
Discussion: If the tubes were left run indefinitely (until the reactionwas
complete), how would this affect the results? Explain your answer.
5
Discussion: The next experiment you would do if this was yourresearch
project is described in detail, including ahypothesis.
2
References: At least two references are used and are in APA format.One
may be textbook, but do not use the lab manual or Hooblerreference.
1
Grammar and format: Document is typed, left justified, Calibri or Arial10
point font or larger, single spaced, in paragraph form, written in past tense,
uses the correct subject headings
1
Grammar and format: Sentence structure and spelling is correct, words“I”
and “we” are not used, no direct quotes
1 Grammar and format: Document printeddouble-sided
10 Teamwork Evaluation: Points awarded based on how your professorand
team members evaluate your participation andcontribution
60 Total points for the lab report
60 Total points given for lab practical
120 Overall points awarded
100 Percentage Grade (Final grade for lab practical 2)

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APA Style for Citations and References
For this course you should never use direct quotations in your lab reports. Please use your
words and only your words in your reports. When you use information (not words) from a
source, it must be referenced ANDcited.
References are listed alphabetically at the end of the lab report. They can be used byanyone
who reads your document to find your original sources. Each reference should contain at
minimum the following: Author name or names, title of work, and publication date. Anything
taken from the internet should include the URL and the date the work wasreferenced.
Citations appear in the text of the document and refer the reader to the reference that wasthe
source of the preceding information. The correct format for in-text citations is to include the
author’s name (or an abbreviated version of the title if no author is available) and the year of
publications. It should be immediately obvious what reference a citation is referring to; if thisis
not the case then you are doing somethingwrong.
Here are some examples for how to reference and cite some common materials you may usein
writing your lab report.
Books and Journals
The reference needs to include enough information to ensure a reader can find it quickly,
easily, and specifically. If only part of a work is referenced (e.g. a chapter of a book) thatshould
be noted.
Author name or names. (Year of publication). Title of article or chapter. Title of journal or book,
Volume (issue), page numbers.
Brooker, Robert, Eric Widmaier, Linda Graham, and Peter Stiling. (2014). Simple Patterns of
Inheritance. Biology 3
rd
Edition, 321-342.

Herbst-Damm, K.L., & Kulik, J.A. (2005). Volunteer support, marital status, and the survival
times of terminally ill patients. Health Psychology, 24, 225-229.
In-text citations should use the format (author, year of publication).
Gregor Mendel made thousands of crosses of peasin his lifetime (Brooker, 2014).
People survive difficult times better when they have a support network (Herbst-Damm & Kulik,
2005).

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Websites (List as much information as possible; you may need to hunt around the webpageto
find all the information)
Author name or names. (Date of Publication). Title of webpage. Retrieved [date] from [web
address]
Harris, William. (18 January 2001). “How DNA Evidence Works.” Retrieved 6 January 2014 from
http://science.howstuffworks.com/life/genetic/dna-evidence.htm
Half of a person’s DNA markers come from their mother and half from their father (Harris,
2001).
If there is no author given for a website, then the reference should begin with the name ofthe
webpage, which should also be used in the citation:
“Apomixis.” (2 January 2014). Retrieved 6 January 2014 from
http://en.wikipedia.org/wiki/Apomixis
Apomixis is the asexual reproduction of plants through seeds (Apomixis, 2014).
If there is no date of publication given for a website use the abbreviation n.d. The citation
should also include this abbreviation.
Johnson, Tina. (n.d.). “Foods Rich with Enzymes.” Retrieved 6 January 2014 from
http://www.mbspirit.net/uploads/Foods_Rich_with_Enzymes.pdf
Many of the foods we eat contain enzymes (Johnson, n.d.).
Social media sites such as YouTube can also be used as references. The screen name and,if
possible real name, of the person posting the information should be used.
Author, A. A. [Screen name]. (Date of Publication). Title of video [Video file]. Retrieved [date]
from [web address]
Andersen, Paul. [Bozeman Science]. (21 April 2012). Meiosis. Retrieved 6 January
2014 from http://www.youtube.com/watch?v=rB_8dTuh73c
7DrDon. (16 May 2011). Protein synthesis (DNA transcription, translation and folding) . Retrieved 6 January 2014 from http://www.youtube.com/watch?v=erOP76_qLWA
The female gamete is the egg and the male gamete isthe sperm (Andersen, 2012).
Translation, or production of the protein, occurs at the ribosome (7DrDon, 2011).

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How To Avoid Plagiarism
Plagiarism is claiming someone else’s words as your own and will results in a grade of 0 inthis
course. The purpose of writing a lab report is to demonstrate understanding of thematerial;
copying-and-pasting someone else’s work indicates that this has not been achieved.
For example, a student wants to use the following information in the labreport:
A molecule or compound is made when two or more atoms form a chemical
bond, linking them together. The two types of bonds are ionic bonds and
covalent bonds. In an ionic bond, the atoms are bound together by theattraction
between oppositely-charged ions. For example, sodium and chloride form an
ionic bond, to make NaCl, or table salt. (Helmenstine,n.d.)
It would NOT be acceptable to quote any part of this information; direct quotes are not allowed
in your lab report. It would also NOT be acceptable to only slightly modify the wording ofthis
information. For example:
Molecules or compounds are formed when two or more atoms are linked in a chemical bond.
Ionic bonds and covalent bonds are the two types of bonds. In ionic bonds, atoms are held
together by attractions between oppositely-charged ions (Helmenstine, n.d.).
The sentences above are plagiarized and would earn this student a 0 on the lab report. They
do NOT demonstrate understanding of the science that is being explained.
The simplest way to avoid plagiarism is to read the material, set it aside, and withoutlooking
at it write what you remember from what you read. This way the content or learning fromthe
material will be in your own word. For example,
Chemicals are formed through two types of bonds, covalent bonds and ionic bonds. These
bonds hold atoms together to make compounds and molecules. Ionic bonds are formed by
attractions between positive and negative ions (Helmenstine, n.d.).
These sentences have the same information, but the writing style is quite different. The
changes show that the student understands what is beingwritten.
References:
Helmenstine, Anne Marie. (n.d.). “What Is the Difference Between an Ionic andCovalent
Chemical Bond?” Retrieved 6 January 2014 from
http://chemistry.about.com/od/chemistrystudentfaqs/f/bondtypes.htm.

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Sample Lab Report #2
Name: James Bond
Lab: Lab #9, Enzymes, Effects of pH on EnzymeActivity
Due date:

Purpose

The purpose of this experiment was to study the effects of pH on catalase enzymeactivity.

Introduction

Every chemical reaction within the cell requires an enzyme to lower its activation
energy. Even exergonic reactions happen too slowly to be useful without a catalyst. Almostall
enzymes are proteins. To catalyze a reaction, the enzyme must interact with the reactant or
reactants. This interaction takes place in a region of the enzyme called the active site. The
reactant, or substrate for the enzyme, must fit perfectly into the active site of the enzyme in
order for the enzyme to operate. Therefore, most enzymes are only able to catalyze a single
chemical reaction. This is called specificity, and most enzymes are very specific (Cecamgmmacz,
2011). Under favorable conditions, the enzyme can operate with maximum efficiency, andthe
chemical reaction occurs very rapidly. This is an enzyme’s optimum activity (Brooker,2011).
Some environmental conditions, e.g. temperature and pH, can affect an enzymes activity. The
concentration of enzyme or substrate can also have a dramatic effect on enzyme activity, and
that is the variable studied in thisreport.
The enzyme being studied was called catalase, which was isolated from potato andliver.
Its substrate is hydrogen peroxide, and its products are oxygen gas and water. In this
experiment the behavior of the catalase enzyme was tested at a variety of different pHlevels.
A neutral pH of 7 was used as the control environment because the enzyme would react
favorably in this environment, since most living organisms (including potatoes) maintain a
relatively neutral internal environment.

• Catalase isolated from potatoes
• Hydrogen peroxide
• Water
• HCl
• NaOH

Materials

• Wax pencil
• Metric ruler
• Test tubes
• Pipettes

Methods

Test tubes 1-3 were numbered and labeled at 1cm, 3cm, and 7cm from the bottomof
the tube. Each was filled to the 1cm mark with potato juice (catalase). Tube 1 was filled tothe
3cm mark with HCl, tube 2 was filled to the 3cm mark with distilled water, and tube 3 wasfilled
to the 3cm mark with NaOH. Each tube was then allowed to sit for 5 minutes atroom
temperature. Then, one at a time, each tube was filled to the 7 cm mark with hydrogen
peroxide and, after 20 seconds had elapsed, the bubble column height was measured and
recorded. Tube 2 overflowed, so the height of the tube was recorded as the bubble column
height for thatsample.

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0 0

Results

The greatest enzyme activity was seen at pH 7, which had 120cm of oxygen bubbles. At
pH 4, 0 cm of oxygen bubbles were measured and at pH 12, 0 cm of oxygen bubbles were
measured.

Height of Bubble Column in cm

14

12

12
10
8
6
4
2
0

pH = 4 pH = 7 pH = 12

Height of Bubble Column in cm

Discussion

Only one tube, the tube at pH 7, had a measurable amount of oxygen bubbles,showing
that the enzyme was active. Normal physiological pH is 7.4, so this tube was very close tothe
normal pH of living cells. The enzyme catalase was able to work well under these conditions.
At pH 4 and pH 12, the enzyme was not active. These extreme pH levels denatured the
catalase, changing its shape so that it could not break down the hydrogen peroxide(Brooker,
2011).
This experiment could have been improved by making it possible to measure smaller
changes in pH. This would have allowed comparisons of pH values close to 7, such as 7.8 or7.3.
Under these conditions, it would have been possible to determine exactly which pHchange
inactivatesthe enzyme.
Future experiments could include the one described above. Another similarexperiment
could test other important enzymes such as proteases or lipases under different pHconditions.
Another could test the enzymes found in the stomach, which are normally active at acidic pH
values. The results seen here would predict that these enzymes would not be inactivated by
acidity, but instead might be inactive at neutral pH.
References

Brooker, Robert, Eric Widmaier, Linda Graham, and Peter Stiling. (2011). An Introductionto
Energy, Enzymes, and Metabolism. Biology 2nd Edition, 118-135.
Cecamgmmacz. (14 July 2011). Enzymes activation energy [Video file]. Retrieved 2February