Procedure I – Net Photosynthesis Rates – 100% Illumination
Complete the tables below using your data and information found under the Background tab (see the Summary of Needed Formulas section)
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| Leaf
Sample Type |
Illumination
Level |
Oxygen
Concentration Change Data (ppm) |
Elapsed
Time (s) |
Oxygen
Change Rate (ppm/s) |
| Sun-
Adapted |
100% | 21.36 | 40.0 (s) | |
| Shade-Adapted | 100% | 12.96 | 40.0 (s) |
| Leaf
Sample Type |
Illumination
Level |
Carbon Dioxide
Concentration Change Data (ppm) |
Elapsed
Time (s) |
Carbon Dioxide
Change Rate (ppm/s) |
| Sun-
Adapted |
100% | -21.36 | 40.0 (s) | |
| Shade-Adapted | 100% | -12.96 | 40.0 (s) |
Observations and Questions
[1] Show your oxygen change rate calculation for the Sun-Adapted data run.
[2] Show your carbon dioxide change rate calculation for the Shade-Adapted data run.
[3] Examine your results. Do your results reveal a possible relationship between (rates of) production of oxygen and carbon dioxide? Explain. Cite your results as part of your explanation.
[4] Using your results for change in oxygen concentration as a reference, discuss whether your Procedure I results confirm research findings about differences in the amount of chlorophyll production for sun-adapted and shade-adapted leaves.
[5] How is the net photosynthesis rate related to the rates you determined? (note that this is not a calculation)
[6] Explain why (or why not) you would expect respiration to occur when the illumination is 100%?
Procedure II – Respiration Rates – 0% Illumination Data Run
Complete the tables below using your data and information found under the Background tab (see the Summary of Needed Formulas section)
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| Leaf
Sample Type |
Illumination
Level |
Oxygen
Concentration Change Data (ppm) |
Elapsed
Time (s) |
Oxygen
Change Rate (ppm/s) |
| Sun-
Adapted |
0% | -14.01 | 40.0 (s) | |
| Shade-Adapted | 0% | -8.41 | 40.0 (s) |
| Leaf
Sample Type |
Illumination
Level |
Carbon Dioxide
Concentration Change Data (ppm) |
Elapsed
Time (s) |
Carbon Dioxide
Change Rate (ppm/s) |
| Sun-
Adapted |
0% | 14.01 | 40.0 (s) | |
| Shade-Adapted | 0% | 8.41 | 40.0 (s) |
Observations and Questions
[7] Sample Calculation: Show your oxygen change rate calculation for the Sun-Adapted data run.
[8] Sample Calculation: Show your carbon dioxide change rate calculation for the Shade-Adapted data run.
[9] Cite your results for the change in carbon dioxide concentration as a reference and compare the respiratory rates for sun-adapted and shade-adapted leaves. Explain the biological principles/bases underlying this comparison.
[10] What would be the photosynthesis rate if you measured it at 0% illumination in Procedure II? Explain your answer. Cite your results from Procedure I to assist with your explanation.
Procedure III – Low-Light Net Photosynthesis Rates – 15% Illumination
Complete the table below using your data and information found under the Background tab (see the Summary of Needed Formulas section)
| Leaf
Sample Type |
Illumination
Level |
Oxygen
Concentration Change Data (ppm) |
Elapsed
Time (s) |
Oxygen
Change Rate (ppm/s) |
| Sun-
Adapted |
15% | 4.78 | 40.0 (s) | |
| Shade-Adapted | 15% | 8.19 | 40.0 (s) |
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Observations and Questions
[11] Sample Calculation: Show your oxygen change rate calculation for the Sun-Adapted data run.
[12] Based on the data you collected in Procedures I (100% illumination) and III (15% illumination), which system of leaves produces the most oxygen: Sun-adapted or shade-adapted? Explain how your results support your answer.
[13] Are your results from Procedure II and Procedure III consistent with research findings that there are differences in chlorophyll production and enzyme activity between shade-adapted leaves and sun-adapted leaves? Explain your reasoning. Cite your results from Procedure II and Procedure III to support your explanation.
