Lab 9 Cellular Respiration
After completing the lab report, save and attach to the correct drop box.
Scroll to the bottom of the Lab and click on Fermentation of Yeast Procedure to complete the lab and lab report as follows:
Experiment 1: Fermentation by Yeast Procedure
Data Tables and Post-Lab Assessment
Table 1: Yeast Fermentation Data
Tube Initial Gas Height (mm) Final Gas Height (mm) Net Change
Post-Lab Questions
1. Include your hypothesis from Step 1 here. Be sure to include at least one piece of scientific reasoning in your hypothesis to support your predictions.
2. Did you notice a difference in the rate of respiration between the various sugars? Did the artificial sugar provide a good starting material for fermentation? Explain your answer.
3. Was anaerobic fermentation occurring? How do you know (use scientific reasoning)?
4. If you observed respiration, identify the gas that was produced. Suggest two methods you could use for positively identifying this gas.
5. Hypothesize why some of the sugar or sweetener solutions were not metabolized, while others were. Research the chemical formula of Equal® and Splenda® and explain how it would affect yeast respiration.
6. How do the results of this experiment relate to the role yeast plays in baking?
7. What would you expect to see if the yeast cell metabolism slowed down? How could this be done?
8. Indicate sources of error and suggest improvement (for example, what types of controls could be added?).
NOW Scroll to the bottom of the Lab and click on Aerobic Respiration in Beans Procedure to complete the lab and lab report as follows:
Experiment 2: Aerobic Respiration in Beans
Data Tables and Post-Lab Assessment
Table 2: Bromothymol Blue Color Change Over Time for Pinto Bean Trial
Time Pre-Soaked Pinto Beans Dry Pinto Beans No Pinto Beans
0 min
30 min
60 min
90 min
120 min
150 min
180 min
24 hours
Table 3: Bromothymol Blue Color Change Over Time for Kidney Bean Trial
Time Pre-Soaked Kidney Beans Dry Kidney Beans No Kidney Beans
0 min
30 min
60 min
90 min
120 min
150 min
180 min
24 hours
Post-Lab Questions
1. For Experiment 2 -Extra Credit insert a .jpg of you and your beans showing the color of the bromothymol indicator at the end of the experiment here:
2. How did the color of the bromothymol blue solution in each beaker change over time in each condition?
3. What is the mechanism driving the bromothymol blue solution color change?
4. What can be inferred from the color change of the bromothymol blue solution?
5. Did you find differences in the rates of respiration between Pinto beans vs. Kidney beans, if so why?
6. What evidence do you have to prove that cellular respiration occurred in the beans? Explain your answer.
7. What are the controls in this experiment, and what variables do they eliminate? Why is it important to have a control for this experiment?
8. If this experiment were conducted at 0 °C, what difference would you see in the rate of respiration? Why?
9. Would you expect to find carbon dioxide in your breath? Why?