Darwin’s theory of Natural Selection was influenced by his observation that farmers regularly select individual plants and animals that have specific traits for breeding. This process is referred to as artificial selection. For thousands of years, humans have selected plants and animals for different traits such as hardiness, drought tolerance, productivity, etc. After multiple generations of selective breeding, a strain or breed is established. The domestic dog is an excellent example of this process. All dogs can interbreed and are derived from the same genetic stock.

The yeast Saccharomyces sp. is another excellent example of artificial selection. Different strains of yeast are used to make beer, bread, and wine. As a result, brewers and bakers have used artificial selection to select very specific strains of yeast for each purpose.


In this Preliminary Activity, you will use a CO2 Gas Sensor to determine the rate of respiration of glucose by baker’s yeast.

After completing the Preliminary Activity, you will first use reference sources to find out more about yeast strains that are used in baking and brewing before you choose and investigate a researchable question dealing with the evolution of yeast through artificial selection. Some topics to consider in your reference search are:

  • Saccharomyces cerevisiae
  • Saccharomyces bayans
  • beer yeast
  • wine yeast
  • artificial selection
  • evolution
  • baking
  • monosaccharides
  • disaccharides
  • metabolism