Name: ________________________________________
Date:_______________
Yeast Fermentation Lab: Day 1 Control Testing
Purpose: to observe the effect of environment on yeast activities. This is a lab in which you will
design and carry out your own experiment. The experiment will answer a question you have
about the cellular process of fermentation using the model organism yeast. Note: this will be a lab
report lab.
Materials:
dry active yeast
ruler
string
15-20 mL test tube (preferably one without a lip)
balloon
sucrose (table sugar)
warm water
thermometer
hot plate
Part 1- Procedure:
1) Fill the test tube with 15 mL of warm tap water. You can heat up some water on a hot plate
until it gets a bit warm if the tap does not get warm on its own. Maybe come up with a set
temperature as a class?
2) Add 1 gram of yeast to the warm water and stir until it is in solution.
3) Complete the lab according to the group you have been assigned.
Group 1: After making your yeast solution in a test tube, immediately place the balloon on the
top of the test tube. Note the time on your lab chart.
Group 2: After making your yeast solution in a test tube, add 2 grams of sugar to the mixture and
swirl it gently until it dissolves. Then place the balloon on top of the test tube. Note the time on
your lab chart.
Group 3: After making your yeast solution in a test tube, add 4 grams of sugar to the mixture and
swirl it gently until it dissolves. Then place the balloon on top of the test tube. Note the time on
your lab chart.
Group 4: After making your yeast solution in a test tube, add 6 grams of sugar to the mixture and
swirl it gently until it dissolves. Then place the balloon on top of the test tube. Note the time on
your lab chart.
Group 5: After making your yeast solution in a test tube, add 8 grams of sugar to the mixture and
swirl it gently until it dissolves. Then place the balloon on top of the test tube. Note the time on
your lab chart.
5) Using your string, measure the size of your balloon every 5 minutes. Record the information
on your data table.
Results:
Title:_________________________________________________________________________________________________________
Time (min)
Group 1
Group 2
Group 3
Group 4
Group 5
0
5
SIZE OF BALLOON (cm)
10
15
20
25
Discussion: Please answer on a separate piece of paper, or type up. These will eventually be
incorporated into your lab report in some way.
1) Which of the balloons reached the largest size? What material was collected in the balloons?
2) What were the variables in this experiment?
3) Which one of the groups was the negative control? Why was it the negative control?
4) Make a multi-line graph of the data. Include a legend. (Attach to this handout). Please do this
in Excel.
5) What is fermentation? What are the products of fermentation? What caused the balloons to
increase in size?
6) What does your group think is the ideal amount of sugar to use for the next series of
experiments?
Part 2. Variable testing
Other possible materials you could use: you must let me know ahead of time if you need to
use any of the below materials so that I can prepare them in advance.
HCl
NaOH
Salt
Glucose (dextrose)
Starch
pH paper
Other liquid sources of sugar (you bring in)
Artificial sweeteners (you bring in)
Part A. Develop your hypothesis
What do you think are the requirements of fermentation by yeast? What will make fermentation
more effective or less effective? Develop a provable hypothesis about a question you have about
fermentation.
Part B. Design your experiment:
The control will be the same for everyone. Pick one variable to manipulate for the remaining 3
test groups in the experiment. Make sure you make a data table that shows all the conditions
for each test group and shows which dependent variables you will monitor (3 minimum).
You must have some sort of quantitative data and some sort of qualitative data.
Control test tube set up:
Use ideal set up from day 1. See question 6 from above.
Part C: Conduct your experiment:
The date you must be prepared to conduct your experiment is:______________
Part D: Analyze your data (at home):
Use graphs, compare and contrast. Try to explain your results based on what you know about
the subject.
Part E: Write up
You will do a formal lab write up for this experiment. The rubric will be posted on the class
website.