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:

\text{C}_{6}\text{H}_{12}\text{O}_{6} \rightarrow \text{2 } \text{CH}_{3}\text{CH}_{2}\text{OH} + \text{2 } \text{CO}_{2} + \text{energy}

The metabolic activity of yeast can be determined by the measurement of gas pressure inside the fermentation vessel.


In this Preliminary Activity, you will use a Gas Pressure Sensor to monitor the pressure inside a conical 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. Some topics to consider in your reference search are:

  • sugars
  • glucose
  • monosaccharides
  • disaccharides
  • fermentation
  • anaerobic respiration
  • aerobic respiration
  • yeast
  • enzyme
  • substrate
  • enzyme inhibitor