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Bio100 Appendix G

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Interpreting Your Data Plots
Although basic trends in your data can sometimes be estimated by simply looking at the data points on your scatter plots, quantitative measures of the effects you are studying can only be determined by fitting a curve to your data.
Curve fitting involves producing a statistically derived best-fit line of data points on the graph; not a hand-drawn or estimated line connecting data points.
Once you have plotted your data, a Plot # tab will appear at the top of the Plot Data screen. Clicking on this tab will take you to the curve-fitting functions of LeafLab and allow you to switch between plots that you generate.
1. Click on the Plot 1 tab to enter the curve-fitting view.

• An enlarged view of the …show more content…

Study the curve of Photosynthetic Rate vs. Light in Tomato to answer the questions below.
The following is a representative plot and table from this experiment: Series Intercept Slope Asymptote Error Sum of Squares
1 -1.3 0.038 17.1 0.198

1. Answer the following questions:

• What is the relationship between an increase in light intensity and photosynthetic rate in tomato leaves?
• Does this relationship support the hypothesis that you formulated?

An increase in light intensity increases photosynthetic rate, supporting the hypothesis.

• Photosynthetic saturation is the maximum rate of photosynthesis. What was the value for photosynthetic saturation in tomato leaves?
• What value of light intensity produced photosynthetic saturation in tomato leaves?
• Based on what you know about photosynthesis, provide possible reasons for what causes photosynthetic saturation (these cannot be determined from the plot).

Photosynthetic saturation in tomato leaves will occur at a light intensity of approximately 1600 mol/m2/s. At saturation, photosynthetic rate is approximately 15-17 (as indicated by the asymptote).

Exploration Experiment: Light Intensity and Photosynthetic Rates in Corn

1. Follow the steps detailed in the first experiment to test the effects of an increase in light intensity on photosynthetic rates in corn (a C4 plant).

• The only modification to the experiment is that you will need to use a high rate of gas

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