Yeast can metabolize sugar in two ways, aerobically, with the aid of oxygen, or anaerobically, without oxygen. When yeast metabolizes a sugar under anaerobic conditions, ethanol (CH3CH2OH) and carbon dioxide (CO2) gas are produced. An equation for the fermentation of the simple sugar glucose (C6H12O6) is:
The metabolic activity of yeast can be determined by the measurement of gas pressure inside the fermentation vessel.
In the Preliminary Activity, you will use a Gas Pressure Sensor to monitor the pressure inside a test tube as yeast metabolizes glucose anaerobically. When data collection is complete, you will perform a linear fit on the resultant graph to determine the fermentation rate.
After completing the Preliminary Activity, you will first use reference sources to find out more about sugar fermentation by yeast before you choose and investigate a researchable question dealing with fermentation.
Sensors and Equipment
This investigation requires each of the following Vernier sensors and equipment (unless otherwise noted):
Step-by-step instructions for the Preliminary Activity
List of materials and equipment
Note: The experiment preview of the Preliminary Activity does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.