Students set up a simple way to indirectly observe and quantify the amount of respiration occurring in yeast-molasses cultures. Each student adds a small amount of baking yeast to a test tube filled with diluted molasses. A second, smaller test tube is then placed upside-down inside the solution. As the yeast cells respire, the carbon dioxide they produce is trapped inside the inverted test tube, producing a growing bubble of gas that is easily observed and measured. Students are presented with the procedure for designing an effective experiment; they learn to think critically about experimental results and indirect observations of experimental events.

Concepts

cellular respiration, engineering, experimental design, respiration, yeast, stem

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Additional Tags

yeast cultures, integrated teaching and learning program and laboratory, teachengineering, cell respiration

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Classroom Considerations

• Knovation Readability Score: 4 (1 low difficulty, 5 high difficulty)