Grade Level/Subject
9 / Biology
Unit
Cellular Energetics
Enduring
Understanding
Cells have specific structures and functions for
obtaining and storing energy needed to carry
out biological processes.
BIO.2 The student will investigate and
understand the chemical and biochemical
principles essential for life. Key concepts
include d) the capture, storage, transformation,
and flow of energy through the processes of
photosynthesis and respiration.
BIO.1 The student will demonstrate an
understanding of scientific reasoning, logic, and
the nature of science by planning and
conducting investigations.
Measuring Fermentation
SOL Objectives
Title
Lesson Objective
Inquiry Level
Materials Required
Students will be able to:
 Identify the components of energy
capture, storage, and release
 Explain how some organisms can produce
energy without oxygen
 Design and safely perform a controlled
experiment with an appropriate scientific
question, hypothesis, procedure, analysis,
and conclusion.
3 (The question is given; the methods and
solution are both open).
Fast-acting yeast, sugar, water, test tubes,
other test substances desired by students, and
one or more of the following methods for data
collection: BTB (bromothymol blue), balloons,
rulers, Vernier (or similar) CO2 sensor
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Measuring Fermentation
Background:
Yeast are microorganisms in
the Fungi kingdom. Therefore,
they are eukaryotic (have a
membrane-bound nucleus and
other membrane-bound
cellular organelles) and
heterotrophic (consumers). A
typical yeast cell is shown in
the figure on the right.
In order to get energy, yeast require a food source (they are not
photosynthetic!). Then, yeast must break down that food source through a
series of metabolic reactions. There are many different species of yeast,
some of which perform fermentation. Fermentation is an anaerobic process
that breaks down a carbohydrate (such as sugar or starch).
As shown in the diagram above, carbon dioxide is a product of fermentation.
In bread making, this carbon dioxide forms air pockets, giving bread a light,
airy texture.
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Key Facts:
 Yeast metabolize through fermentation.
 Sugar provides an energy source for yeast.
 Carbon dioxide is a product of fermentation.
 Carbon dioxide is a gas. In a closed system, an increase in the
amount of gas could form an air bubble and, in sufficient amounts,
could inflate a balloon.
 When carbon dioxide mixes with water, the resulting solution is acidic.
 Bromothymol blue is an indicator that is blue in neutral solutions and
turns yellow in acidic solutions.
 Sensors / probes can be used to measure the levels of dissolved gases
in solutions.
Goal:
 Using the background information and key facts, develop and carry out
an investigation to measure the amount of fermentation occurring in
yeast.
 Identify a variable that you would like to test to see its impact upon
fermentation in yeast.
 Implement your procedure only after it has been approved by
your teacher.
 Make sure that you:
o Clearly state your hypothesis.
o Identify your independent and dependent variables.
o Include a control.
o Think about whether your procedures will give you quantitative
or qualitative data.
o Include clear, step-by-step procedures.
o Develop and fill out a data table to present your results.
o Summarize your results in a conclusion.
 Your lab will be graded using the rubric on the following page.
3
Basis for Grade
Points Available
Completed experimental
design diagram
20
Detailed procedures
10
Data table – columns and rows
clearly labeled, with units
10
Points Earned
Conclusion paragraph:

Summary of results
(highlight major
findings, discuss any
trends in the data)
5

Explanation and
interpretation of
results – what does it
mean? How do you
know?
5

Hypothesis: accepted
or rejected?
5

Evaluation of the
success of the
experiment, including
any explanation of
experimental error
10

Procedural
improvements for the
experiment
5
TOTAL
70
/ 70
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Title: _____________________________________________________
Purpose: _________________________________________________
Hypothesis: _______________________________________________
_________________________________________________________
Independent Variable: ________________________
Level of
Independent
Variable
Number of
Trials
Dependent Variable (include units):____________________________
_________________________________________________________
Constants:
1. ______________________
4. ______________________
2. ______________________
5. ______________________
3. ______________________
6. ______________________
Procedures: in the space below, write detailed procedures that anyone could
follow to replicate your experiment. Follow your teacher’s directions about the
format of these procedures (for instance, paragraphs or numbered list of steps).
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_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
 Create and attach a data table; fill it out based on what you observe
during your experiment. Make sure all columns and rows are clearly
labeled and that units are included where appropriate.
 Finally, write and attach a conclusion paragraph in which you summarize
the results of your experiment. Describe what happened and explain what
it means. Also, mention any possible sources of error in your experiment
and ways that you could improve the experiment if you were to repeat it.
Notes for Teachers:
 Depending on the materials you have available, you may choose to
modify the key facts that are presented to the students (for instance,
if you do not have access to carbon dioxide sensors/probes, this fact
may be irrelevant to your class).
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


One of the goals listed is for students to choose an independent
variable to test its effect upon fermentation in yeast; some commonly
chosen IVs for this experiment might include temperature and
concentration of sugar. Obviously, you can tailor this to the materials
that you have available in the classroom. Also, this is a portion of the
inquiry activity that lends itself well to differentiation. Of course, if
time is a factor, you may ultimately decide to omit this portion of the
inquiry.
Remember to check to make sure that the yeast is, in fact, active.
Some teachers have a strong preference for the fast-acting yeast,
particularly if you want to get results within one class period (as
opposed to letting things sit overnight).
Some teachers prefer to give students a solution of yeast that is
actively respiring in sucrose (as opposed to giving students the
separate components to mix on their own); there are multiple sources
online which will offer guidance in terms of ideal temperatures and
sucrose concentrations to get this set up.
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