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Science - Biology
Standard 1 Objective 2
6 class periods of 45 minutes each
Over a multiple-day period, students will conduct an experiment with yeast to investigate the effects of different variables on carbon dioxide production. This series of lessons will focus on fermentation, or anaerobic respiration, which is a major proponent of the carbon cycle.
From the carbon cycle model you have created with your students, there are multiple lines/arrows pointing back to the atmosphere labeled cellular respiration. This lab will investigate the process of respiration further. There are two types of cellular respiration: aerobic (requiring oxygen) and anaerobic (lacking oxygen).
Yeasts are heterotrophic organisms, meaning they need to acquire their food for energy. Classified as a type of fungus, yeasts obtain energy from sugar (glucose) in an aqueous environment by a specific anaerobic process called fermentation. There are two types of fermentation: lactic acid fermentation (which occurs in our muscle cells when they are oxygen deprived) and alcoholic fermentation (which is involved in food production, such as bread, cheese, beer and wine). Alcoholic fermentation begins once glucose diffuses into the yeast cell. The glucose is broken down into two 3-carbon molecules called pyruvic acid. The pyruvic acid is then broken down into carbon dioxide, ethanol and energy for the yeast cell. The carbon dioxide is released in a gaseous state and can be seen bubbling in a bottle or as the gas fills a balloon (which is why bread rises).
Students should have participated in the two previous Carbon Cycle lesson plans. In addition, experience with the scientific process (question, hypothesis, methods, data collection, graphing, conclusion) is highly suggested. If not, use this lab to provide an example of how a lab can be run, from question to conclusion.
1. Use Science Process and Thinking Skills
Students will take notes in their science notebooks throughout the class period. Notebooks will be collected once a week and assessed based on a rubric.