# Cellular Respiration

Prarthana Minasandram

Partner: Ben Liu

Introduction

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. Variables

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 all treatments will start at zero. See Appendix A for Tables 5-8.

Sample Calculation for Average Increase in CO2 Bubble Size

Group (Trial) 1 Measurement + Group (Trial) 2 Measurement + Group (Trial) 3 Measurement + Group (Trial) 4 Measurement + Group (Trial) 5 Measurement

Number of Trials

Average Size of CO2 Bubble at 5 Minutes

5 mm + 2 mm + 0 mm + 0 mm + 1 mm

5= 1.6 mm

Error: 2mm + 2mm + 2mm + 2mm + 2mm

5

= ± 2 mm

Average Size of CO2 Bubble at 5 Minutes = 2 mm ± 2 mm as adjusted for significant figures

Table 10. Average Increase in Size of CO2 Gas Bubble in mm of Yeast with Various Solutions Treatment| Time in Minutes (± 0.5 minute)|

| 0| 5| 10| 15| 20| 25| 30| 35|

A| 0| 2| 2| 3| 3| 3| 5| 6|

B| 0| 1| 2| 3| 3| 4| 6| 9|

C| 0| 1| 2| 2| 2| 2| 2| 2|

D| 0| 0| 1| 1| 1| 1| 1| 1|

*Because the scale of the graph is so small, the error bars obstruct clear view of the regression lines. For clarity purposes, the error bars have been removed in the duplicated graph below.

*Error is ± 2 mm

Conclusion and Evaluation

The hypothesis stated: 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. The experiment failed to disprove both parts of the hypothesis. Treatment A consisted of yeast with a 5% glucose solution. Over time, CO2 production increased, but because the data had to be adjusted for significant figures, the graph does not appear as smooth as the transition was observed during the lab. The data can be observed by the red line in both Figures 1 and 2. The equation for the regression line for Treatment A is modeled by y = 0.0238x2 + 0.5x + 0.1429 with an R² value of 0.8968. This number is relatively close to 1, indicating that the line of best fit is a...

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"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. .

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