Partner: Ben Liu
Purpose: To examine the rate of alcoholic fermentation using various carbohydrates.
Hypothesis: If the yeast is placed in 5% glucose or sucrose solutions, then carbon dioxide production will increase over time. If boiled yeast is placed in a 5% sucrose solution, then carbon dioxide production will remain constant.
Independent variable: Carbohydrate solutions (5% solutions of glucose and sucrose) and boiled yeast
Dependent variable: Rate of reaction of alcoholic fermentation as calculated by size of CO2 bubble (measuring the top of the bubble to the bottom with a ruler)
Control Group: Yeast suspension with only distilled H2O (because it lacks a substrate)
Controlled Variables: testing environment (ie. atmospheric temperature, atmospheric pressure), ruler used, type and size of test tubes used, type and yeast, amount of glucose or sucrose solutions, amount of yeast (regular or boiled), time increments measured.
To control these variables, every trial will be conducted at the same temperature while using the same ruler. All samples will have 3 mL of yeast (regular and boiled) and either 3 mL of sucrose or glucose solutions or 3 mL of water. All measurements will be taken from the top of the air bubble to the bottom of the air bubble and will be measured every 5 minutes for 35 minutes.
Materials: See lab handout
Procedure: See lab handout
Data Collection and Processing
**See Appendix A for raw data and observations
Sample Calculation for Increase in CO2 Bubble Size
Sample Calculation is based on data taken from Table 6 after 5 minutes. All other average calculations were done in a similar manner. All calculations in Tables 5-9 are rounded to1 significant figure.
Size of CO2 bubble after (x) minutes – initial size of bubble = increase in size
*This process is done so that it will be easier to see a visual comparison of the data when graphed since
Cited: "Photosynthesis." Biology at Clermont College. N.p., n.d. Web. 21 Apr. 2013. . "Photosynthesis in Nature." Estrella Mountain Community College. N.p., n.d. Web. 24 Apr. 2013. . "The Inverse-Square Law." Institute for Astronomy. N.p., n.d. Web. 24 Apr. 2013. .