BIOLOGY Lab Investigation: Fermentation in Beverages
Introduction: Fermentation in food processing typically is the conversion of carbohydrates to
alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof,
under anaerobic conditions, meaning oxygen is absent. A more restricted definition of
fermentation is the chemical conversion of sugars into ethanol. French chemist Louis Pasteur
was the first known zymologist (someone who studies fermentation), when in 1856 he
connected yeast to fermentation. Pasteur originally defined fermentation as "respiration without
air". Pasteur performed careful research and concluded:
"I am of the opinion that alcoholic fermentation never occurs without simultaneous
organization, development and multiplication of cells.... If asked, in what consists the
chemical act whereby the sugar is decomposed ... I am completely ignorant of it”.
Uses: The primary benefit of fermentation is the conversion of sugars and other carbohydrates,
e.g., converting juice into wine, carbohydrates into carbon dioxide to leaven bread, and sugars
in vegetables into preservative organic acids. In addition, fermentation allows glycolysis (the
breakdown of sugar to produce ATP) to continue when oxygen is not present. It differs from
cellular respiration for cellular respiration is aerobic, meaning it requires oxygen to produce
more ATP from glucose when compared to fermentation.
Source: http://en.wikipedia.org/wiki/Fermentation
The Problem [Your Task]: Using the materials provided, you will design an experiment and compare the
rate of fermentation amongst different beverages. You will complete the following:
 Develop a hypothesis
 Design a procedure
 Identify the independent and dependent variables
 Identify experimental constants
 Identify the control
 Collect data and describe if the data is qualitative or quantitative
 Draw a conclusion
 Share and compare your experiment as well as findings with classmates using a poster board (see
second page for format).
Investigative question: Does the amount of sugar in beverages affect fermentation?
Materials:

Test tubes

Yeast (1 spoonful for each liquid)

35 mL of each provided beverage:
o
Beverage1
o
Beverage 2
o
Beverage 3
o
Water






Round balloons
Spoon
Graduated cylinders
Cylinder
String
Ruler
1
Procedure:
1. The variable concentration will be measured during this experiment. Use at least one experimental
factor.
2. Design your procedure and get your teacher’s approval. List the experimental constants and
control.
3. Identify the independent and dependent variables for this experiment.
4. Collect data and record it in the provided data table.
5. Conduct your experiment. Measure carbon dioxide production for 15 minutes during each
experimental trial.
6. Make a poster presentation to present to the class that contains the following (see page three):
•Investigative question
•Hypothesis
•Identify the dependent and independent variables
•Experimental constants
•Control
•Procedure
•Data collected
•Conclusion
Use the following sheet as you perform the experiment:
Investigative question:
Hypothesis:
Dependant and independant varibles:
Experimental constants:
Control:
Procedure:
Data:
Liquid
Grams of Sugar
Circumfrence
Investigative Question:
Hypothesis:
Procedure:
Independent and dependent variable:
Experimental constants:
Control:
Data:
Figure 1. Information needed on poster board.
Conclusion:
Post Lab Questions
1.
Choose the statement that best compares and contrast aerobic and anaerobic processes.
a. Aerobic processes occur in the presences of carbon dioxide, however anaerobic processes occur when
oxygen is present.
b. Aerobic processes produce less molecules of ATP due to oxygen being present when compared to
anaerobic process that do not occur in the presence of oxygen.
c. Aerobic processes produce more molecules of ATP due to oxygen being present in the reaction. Anaerobic
process produce less ATP due to the absence of oxygen.
d. Both process utilize sugar during the reaction, however anaerobic processes include metabolizing nucleic
acids to release energy.
2.
Fermentation and cellular respiration share a similarity for both utilize the same macromolecule during metabolism to
produce ATP. Identify which macromolecule is used:
a. Protein
b. Carbohydrate
c. Lipids
d. Nucleotides
3.
Cellular respiration and fermentation are often confused with one another. Choose which statement below that best
distinguishes one from the other.
a. Cellular respiration produces more ATP because oxygen is present. However, fermentation produces less
ATP than cellular respiration due to oxygen being absent.
b. Cellular respiration produces more ATP due to oxygen being absent. However, fermentation produces the
same amount of ATP when oxygen is present in the reaction.
c. Cellular respiration produces more ATP due to oxygen being present when compared to fermentation.
d. Cellular respiration produces more ATP as it metabolizes proteins due to oxygen being present, however
fermentation produces nucleic acids as a result of a deficit in oxygen.
4.
Lactic acidosis is a type of fermentation that takes place during strenuous exercise. Glucose is metabolized during
exercise to provide energy needed by muscular tissues performing work. It is often associated with sore muscles and
discomfort that may linger for days. Choose from the options below the process that occurs during Lactic acidosis.
a. Protein metabolism
b. Anaerobic respiration
c. Aerobic respiration
d. Cellular metabolism of lipids
5.
A list of beverages is given below, select which one you would expect to produce the most carbon dioxide gas if the
same procedure that was utilized during this lab was recreated using the specified beverages:
 Beverage 1: 50 grams of glucose
 Beverage 2: 35 grams of glucose
 Beverage 3: 15 grams of glucose
a.
b.
c.
d.
6.
Beverage 1
Beverage 2
Beverage 3
There is not enough information to form a valid conclusion.
A group of students were performing the same fermentation lab that you have completed. However, the students did
not follow the recommended amounts of yeast for the experiment. Instead of using one spoonful of yeast for each
solution, they used a ¼ teaspoon, which is significantly less. Explain how this may affect their experimental results.
Justify for answer based off of your knowledge that has been acquired by performing this lab.