Lab Report 5: Metabolism Experiment 1 – Fermentation by Yeast (31 points)© 2013 eScience Labs, LLC. All rights reserved. Instructions: Enter yo
Lab Report 5: Metabolism
Experiment 1 – Fermentation by Yeast (31 points)
© 2013 eScience Labs, LLC. All rights reserved.
Instructions: Enter your experimental data into Table 1 below. Take a picture of your experiment after your last measurement and include your photograph in your lab report below.
| Table 1: Yeast Fermentation Data | |||
| Tube | Initial Gas Height (mm) | Final Gas Height (mm) | Net Change |
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 | |||
Attach Image 1: Labeled Fermentation by Yeast Test Tubes
Instructions: Answer the following questions in complete sentences using correct grammar, spelling, and terminology.
- 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?
-Yes there is a change in the rate of respiration of various sugars. Natural sugars respire faster than artificial sugar.
- How do you know that anaerobic fermentation was occurring?
-Anaerobic respiration can be identified by the breakdown of glucose into ethyl alcohol, carbon dioxide, and energy.
- 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.
– Because of their complex structure few sugars were metabolized faster whereas there the others were not. Sugar molecules with smaller structures like glucose, and fructose can be metabolized easily whereas complex sugar molecules like sucrose, and fructose cannot be metabolized easily.
- If you observed respiration, identify the gas that was produced. Suggest two methods you could use for positively identifying this gas.
-Carbon dioxide gas was produced. CO2 produced can be identified by Durham’s tube and inverted test tube technique.
- How do the results of this experiment relate to the role yeast plays in baking?
-The CO2 gas produced by yeast fermentation plays a role in the baking industry.
- What would you expect to see if the yeast cell metabolism slowed down? How could this be done?
-Slow metabolism in the yeast can be identified by the yeast’s less alcohol and gas production. This slow metabolism may be due to the temperature and lack of sugar sources.
- Indicate sources of error and suggest an improvement (for example, what types of controls could be added?).
– There are several things that can help speed up the growth of yeast. One is to make sure that the yeast is fresh and active. Another is to provide the yeast with a warm, moist environment. Sugar can also help yeast to grow more quickly.
Experiment 2: Aerobic Respiration in Beans (69 points)
© 2013 eScience Labs, LLC. All rights reserved.
Instructions: Enter your experimental data into Tables 2 and 3 below. Take a picture of your experiment after your last measurement and include your photograph in your lab report below.
| 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 | GREEN | GREEN | GREEN |
| 30 min | GREEN | GREEN | GREEN |
| 60 min | HALF GREEN | GREEN | GREEN |
| 90 min | MOSTLY CLEAR GREEN | GREEN | GREEN |
| 120 min | CLEAR GREEN | GREEN | GREEN |
| 150 min | YELLOW | GREEN | GREEN |
| 180 min | YELLOW | GREEN | GREEN |
| 24 hours | DEEP YELLOW ORANGE | LIGHT GREEN | GREEN |
| 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 | |||
Attach Image 2: Aerobic Respiration in Beans Experiment
Instructions: Answer the following questions in complete sentences using correct grammar, spelling, and terminology.
- What evidence do you have to prove that cellular respiration occurred in the beans? Explain your answer.
- How did the color of the bromothymol blue solution in each beaker change over time in each condition?
- What can be inferred from the color change of the bromothymol blue solution?
- What is the mechanism driving the bromothymol blue solution color change?
- Were there differences in the rates of respiration in the pinto beans vs. the kidney beans? How did you come to this conclusion?
- If this experiment were conducted at 0 °C, what difference would you see in the rate of respiration? Why?
7. Would you expect to find CO2 in your breath? Why?
- What are the controls in this experiment, and what variables do they eliminate? Why is it important to have a control for this experiment?
9. What else could you incorporate into this experiment to verify that the gas is responsible for the color change? Design an experiment that shows the steps required.