Using Yeast Fermentation to Suggest and Then Challenge a Model

 

Tested Studies in Laboratory Teaching, 2010, Volume 31

Kosinski, R. J.

Abstract

In the simplest version of this activity, students inoculate a yeast suspension into glucose solutions of several concentrations. The glucose disappears, and the amount of CO₂ produced is directly proportional to the initial amount of sugar in solution. This suggests a simple model of yeast fermentation. To challenge this model, students can perform parallel experiments in which the glucose concentration remains high but the yeast concentration is varied. Below approximately 25% of the standard yeast concentration, gas production appears to cease even though glucose disappears. The students then use data from past experiments to evaluate competing explanations for this phenomenon.

Keywords:  yeast, carbon dioxide, fermentation, Pasteur Effect, anaerobic respiration

University of Delaware (2009)