In this lab, you will try to determine whether yeast are capable of metabolizing a variety of sugars. Although the aerobic fermentation of sugars is much more efficient, in this experiment we will have yeast ferment the sugars anaerobically.
When the yeast respire aerobically, oxygengas is consumed at the same rate that CO2 is produced—there would be no change in the gas pressure in the test tube. When yeast ferment the sugars anaerobically, however, CO2 production will cause a change in the pressure of a closed test tube, since no oxygen is being consumed. We can use this pressure change to monitor the fermentation rate and metabolic activity of the organism.