Biology Cellular Respiration Alcohol Fermentation Lab
Module 4b Lab: Cellular Respira3on
Cellular respira+on is a metabolic process during which organic molecules are broken down to produce energy to
power the cell. Cellular respira+on can be aerobic, which means oxygen is required to oxidize glucose and other
sugars. Many types of cells can also produce energy in the absence of oxygen by anaerobic respira,on. In this
laboratory exercise we are going to study alcohol fermenta,on, a process used by yeast cells. During this process
glucose is converted to ethanol and carbon dioxide and some ATP is synthesized as a result. Fermenta+on
happens in the cytoplasm of the cells according to the following reac+on:
C6H12O6 —> 2C2H5OH + 2CO2 + energy (ATP)
Yeasts are eukaryo+c microorganisms classified in the kingdom Fungi. Yeast is a faculta+ve anaerobe, meaning
that it can par+cipate in aerobic respira+on when possible, but when this is impossible, it respires anaerobically.
The alcohol and the carbon dioxide are waste products produced by the yeast. It is these waste products that we
take advantage of. The chemical reac+on, known as fermenta+on can be watched and measured by the amount
of carbon dioxide gas that is produced from the breakdown of glucose.
Purpose of this lab: To observe evidence indica+ng that the processes of cellular respira+on and fermenta+on occur in a
unicellular fungus (i.e., yeast).
• 4-Plas+c clear and see-through cups (6’’ in length or 16 oz size) OR you can also use 4- 1 liter glass or plas+c seethrough boXles
• 4-Yeast Packets (any brand) – Be sure the packet is not be past the expira+on date as this will cause experiment
to not work correctly
• Sugar (preferably granulated)
• Water (tap water will do just fine)
• Apple cider approx. 50 ml
• Pineapple juice approx. 50 ml
• Sugar solu+on 10% (take 10 tsp sugar and dissolve in 100 ml water) -approx. 50 ml needed
• Cling film
• Measuring cup
• Ruler or measuring tape
• Digital or Phone camera
• Notebook to write down results
• Sharpie Marker
hXps://www.youtube.com/watch?v=e7uwV-R6wQ0 (This video does not show the exact procedure that is
wriXen in this lab but shows how the experiment proceeds as the experiment is carried out)
1. Set up 4 cups or boXles on a counter top or table.
2. Label the cups with a sharpie pen labeling them as Water, Apple Cider, Pineapple Juice and 10% Sugar Water.
3. Add about ½ tsp of yeast to each plas+c cup.
4. Add 40 ml of each of the four solu+ons (use the measuring cup, do not cross contaminate). Mark with a sharpie
the level to which each cup was filled.
5. S+r each cup with a different spoon and lightly cover each of the four containers with a cling film.
6. Observe aker 30 min, 60 min, 120 min. At each observa+on, using a ruler, measure the length of the bubbles
produced by the yeast.
7. Record your data
Lab Report that you Turn In:
You will prepare a short report (at least 2 pages double spaced, no greater than 12pt font in Ariel or Times
Roman) with the following sec+ons:
• hypothesis (a guess on what will happen BEFORE you do the experiment)
• experimental materials and procedure
• results of the experiment.
You must include a reference image that shows you actually performing the experiment.
In the last paragraph of the report you should answer the following ques+ons (do not include the ques-ons in
the report, just the answers):
a. What was the source of energy in apple cider and pineapple juice?
b. How did the physical evidence collected in this inves+ga+on support your hypothesis.
c. What role did yeast have in this experiment?
d. How do the results of this experiment relate to the role yeast plays in bread making?
e. What are some possible sources of error in the experiment?
Observa+ons at the beginning of the
Observa+ons (length of the bubble column (in cm )
30 min 60 min 120 min