March 2024 Visit on Friday, March 15, 2024
Experiment Leads: Kaylie Richard & Emily Hoffmann
Continuing the class environmental theme, we kicked off our mid-semester visit at Murray Middle School, looking at a very common microbe, baker’s yeast! We started the visit with a discussion of how microbes can be found almost everywhere in the world and the vital role they play in the ecosystem. We then transitioned to our experiment where the students first looked at how the concentration of sugar impacted yeast metabolism. In containers filled with the same amount of yeast, students added the same volume of warmed water containing different amounts of sugar. They quickly covered the bottle with balloons and measured how fast the balloon filled with CO2. The faster the balloon filled, the faster the yeast were metabolizing the available sugar. The students observed that the yeast had the fastest metabolism when more sugar was present.
In the second experiment, the students used their knowledge of pH from the previous visit to investigate how the pH of the water impacted the yeast metabolism. They added solutions of baking soda or vinegar to their sugar water (keeping sugar constant here) and measured how fast the balloon filled. Again, they were able to see the importance of environmental conditions for the yeast behavior. Many were surprised about the living nature of yeast that makes up many of the foods like bread that they consume daily. Overall, the active bubbling nature of yeast made for a fantastic hands-on experiment for the students!
