Teaching Cellular Respiration & Alternate Energy Sources with a Laboratory Exercise Developed by a Scientist-Teacher Partnership

Microbial fuel cells are a current research area that harvests electricity from bacteria capable of anaerobic respiration. Graphite is an electrically conductive material that bacteria can respire on, thus it can be used to capture electrons from bacteria. When bacteria transfer electrons to graphite, an electrical potential is created that can produce electricity when in a circuit. A sediment battery is a simple circuit that uses graphite and anaerobic bacteria naturally found in dirt. The electrical potential produced by bacterial respiration on the graphite can be measured on a voltmeter and thus can be used as a visual aid for teaching cellular respiration. The combination of the need for a new learning tool and the expertise of the scientists led to the development of the laboratory exercise described in this article. It uses student-designed sediment batteries to better visualize and measure electron transfer in living cells. This exercise satisfies National Science Education Teaching Standards A and B, and Content Standards A, B, and C. (Contains 4 figures.)