12.3: Lab Report
Exercise A
Employing Steps in the Scientific Method:
- Record the Question that is being investigated in this experiment.
- Record a Hypothesis for the question stated above.
- Predict the results of the experiment based on your hypothesis (if/then).
- Fill in your data below.
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Indicator Used: |
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Tube contents |
Initial color of indicator |
Color after 2 hrs |
Color after 24 hrs |
Acidic or basic? |
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5. What is the color of the indicator at at A) neutral pH, B) Basic pH and C) Acidic pH?
6. What was the purpose of Tube #1 ?
7. What specifically was produced as a result of cellular respiration that changed the color of the indicator?
8. How is carbon dioxide an indicator that cellular respiration is taking place in these peas?
9. Germination is the process by which a dormant seed begins to sprout and grow into a seedling. What are some possible metabolic processes that are required for seed germination?
10. During respiration, a seed metabolizes sugars. What is the source of the sugar metabolized by the seed?
11. What variables do you think may affect the respiration rate of the seeds?
12. The equation for cellular respiration is: C6H12O6 + 6O2 → 6CO2 + 6H2O + 32ATP (1.8.2). The energy released from the complete oxidation of glucose under standard conditions is 686 kcal/mol. The energy released from the hydrolysis of ATP to ADP and inorganic phosphate under standard conditions is 7.3 kcal/mol. Using the equation for cellular respiration above, calculate the efficiency of respiration (i.e. the percentage of chemical energy in glucose that is transferred to ATP). For help with answering this question, refer to the course textbook.
13. How might the process of photosynthesis affect pH? Form a hypothesis.
Exercise B
1. In the space below, draw and label several yeast cells undergoing aerobic respiration and several yeast cells not undergoing aerobic respiration. Label the cytoplasm and nucleus if visible.
Exercise C
Employing Steps in the Scientific Method:
- Record the Question that is being investigated in this experiment.
- Record a Hypothesis for the question stated above.
- Predict the results of the experiment based on your hypothesis (if/then).
- Record your data below.
| Time (min.) | Sacch. 1 | Sacch. 2 | Sacch. 3 | Sacch. 4 |
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0 (initial) |
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The results of this experiment can be presented graphically. The presentation of your data in a graph will assist you in interpreting your results. Based on your results, you can complete the final step of scientific investigation, in which you must be able to propose a logical argument that either allows you to support or reject your initial hypothesis.
5. Graph your results using the data from Table 3.
6. What is the dependent variable? Which axis is used to graph this data?
7. What is your independent variable? Which axis is used to graph this data?
Exercise D
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Time (min.) |
Sacch. 1 |
Sacch. 2 |
Sacch. 3 |
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0 (initial) |
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20 |
The results of this experiment can be presented graphically. The presentation of your data in a graph will assist you in interpreting your results. Based on your results, you can complete the final step of scientific investigation, in which you must be able to propose a logical argument that either allows you to support or reject your initial hypothesis.
5. Graph your results using the data from Table 5.
6. What is the dependent variable? Which axis is used to graph this data?
7. What is your independent variable? Which axis is used to graph this data?
8. Fermentation involves redox reactions . Explain what happens to electrons during a redox reaction and how this changes a molecule’s potential energy.
9. Why did we add the Saccharomyces cerevisiae (baker's yeast) to the fermentation tubes? Specifically, what did the yeast provide to the fermentation mixture?
10. What is the purpose of Saccharomyces cerevisiae (“baker’s yeast) in the bread-making process?
11. We measured the formation of what end product to determine the fermentation rate? Name the end product that we measured.
12. List two specific factors (as they relate to the experiment performed in our lab) that affect the rate of fermentation.
13. What other variables could be investigated that might affect the rate of alcoholic fermentation by yeast?