Name: ________________________________
TOC#
Chemical Equation: Aerobic Respiration
Reactants
Products
C6H12O6 + O2 (gas)  CO2 (gas) + H20 + ENERGY
Glucose + Oxygen Carbon Dioxide + Water + Energy
Chemical Equation: Anerobic Respiration (Alcoholic Fermentation)
Reactants
Products
C6H12O6  2CO2 (gas) + 2C2H6O+ ENERGY
Glucose Carbon Dioxide + Ethyl Alcohol + Energy
Notice the differences between the chemical equations for the two types of cellular respiration above. Aerobic
respiration requires oxygen, while anaerobic respiration (also called alcoholic fermentation) does not use
oxygen as a reactant. Today, we will do an experiment where a single celled eukaryote called “yeast” performs
anaerobic respiration.
Procedure: In the space on the right, created a flow chart of these procedures.
1. You will be setting up your own experiment. The
control will be a balloon with 1 gram of yeast and
50mL of warm water that the teacher will set up as
a class example.
2. Your group will create a unique experiment by
choosing one independent variable.
3. In each balloon there should be two things: a liquid
and yeast. You can choose to vary the liquid type
or liquid additives or you can vary the amount of
yeast. However, make sure only one variable is
changed throughout the experiment.
4. The materials provided with which you can create a
variation are:
a. Liquid Type: examples include Apple juice,
Gatorade, 7-up, Diet 7-up, Sunkist Orange Soda,
tea, soda water
b. Additives: Sugar, Water
c. Yeast: more or less than 1 gram
5. Answer the pre-lab questions before you begin
the lab.
6. With your group, decide upon your experimental
set up and write the experimental set up in the
experiment section below.
7. Check your experimental set up with the teacher; do
not continue until you have done this.
8. Pre-stretch the balloons by blowing them up and
letting out the air a few times.
9. Label the balloon with #1 or #2 specified in the
experiment section and with your group number
and class period.
10. Add your specified amount of yeast into balloon #1
and #2 (1 gram, if yeast is not your variation chose) (continue on the next page)
11. Measure out 50 mL of the liquid you are using for
each balloon by using a graduated cylinder. DO
NOT POUR ANY EXTRA LIQUID BACK INTO
THE ORIGINAL CONTAINER
12. Pour the liquid into the correct balloon and tie the
balloons. Make sure both balloons have as little air
as possible.
13. Go to “Volume Station” and find the volume of
your balloon by submerging the balloon and finding
the displacement.
14. Shake each balloon for 30 seconds. Wait a minute,
and shake again for 30 seconds. Do this 5 times.
15. Place your balloons in the hot water bath. The
yeast needs to be warm in order for it to be
activated.
16. Answer the questions in the analysis part 1 section.
17. Near the end of class, go back to your balloons and
use displacement to measure their end
volume. Collect this data in analysis part 2 and
answer the analysis questions.
Pre-Lab Questions:
1. The equation for aerobic respiration is very similar to the equation of ______________________. What are
the differences between the two equations?
2. In this lab you will be placing yeast into a balloon and then adding a fluid of your choice. The balloon could
expand due to the production of a gas. What gas will the reaction produce? __________________
3. What are the following for the experiment you designed:
Independent Variable: ______________________________________________________
Dependent Variable: _______________________________________________________
Constant(s):________________________________________________________________
Experimental Set Up:
Class Balloon (#1) Balloon (#2)
Balloon (#3)
Control Balloon
Variable 1 Balloon Variable 2 Balloon
Liquid type
(type/additives?)
Amount of sugar in liquid (g)
See note below
Amount of yeast (g)
water
none
1 gram
Volume of Ballon (after tying the balloon)
Note: To calculate the amount of sugar in 50 mL of each beverage, look at the labels. First, determine the total
volume in mL. Also, determine the amount of total carbohydrates per bottle in grams. Use the following
equation below, cross multiply and solve for X.
Total Carbohydrate in grams = X grams
Total Volume in mL
50 mL
Analysis Part 1 (before collecting final data)
1. How will you be able to tell that the yeast is active and fermenting the liquid without opening the balloon?
2. Predict what effect you think your change between balloon #2 and balloon #3 will have on the fermentation
being done by the yeast compared to the control (#1) balloon? Explain your answer.
3. How will you measure this change?
Part 2 (at the end of class- collecting data and analysis)
1. What were the volumes of the balloons in your experiment?
Control Balloon Balloon 1: ___________________ Balloon 2:
___________________
Volume in mL
2. Which balloon produced the most CO2? How do you know?
3. List at least 3 possible sources of experimental error in this experiment. Could these errors be corrected?
How?
1)
2)
3)
4. Which type of respiration did you see? Explain why you think that.
5. Explain how bread rising and sore muscles are related.
6. A glucose-fed yeast cell is moved from an aerobic environment to an anaerobic environment where it must
switch to metabolizing by fermentation. For the cell to continue to generate ATP at the same rate, how much
glucose must it consume in the anaerobic environment compared to the aerobic environment?
a. 1
b. 6
c. 14
d. 19
e. 38
7. Explain the answer you chose in question 5.
8. Your dad decides to try his hand at home-brewing beer. He adds baker's yeast, malt, hops, and sugar into a
gallon of water. He then puts this mix into a gallon bucket without a lid. You wait to see if he will cover the
bucket, but he leaves the mixture exposed to the air. "You know you'll never get any alcohol or carbonation
produced like that," you advise your dad. "What do you mean?" He replies. "I've got the right proportions
of yeast and sugar. It should start fermenting any time now." Help your dad, and explain why he will not get
enough fermentation to produce the type of beverage he wants.