| Explore | |
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| Research Question | How does intermittent light affect the rate of photosynthesis? |
| Predictions | The first experimental setup (10 minutes of intermittent light) would have a slower rate of photosynthesis than the control group (10 minutes of continuous light). The second experimental setup (20 minutes of intermittent light) will have close to the same rate of photosynthesis to the control group. |
| Experimental Design | 3 groups: 1 control group will receive 10 min of continuous light. Test group 1 will receive alternating light for 10 min at 1-min intervals (5 min of total light). Test group 2 will receive alternating light for 20 min at 1-min intervals (10 min of total light). We will use the leaf disk flotation technique with spinach to measure Ps. The sides of all 3 sample containers will be wrapped with aluminum foil--and the top of the test group containers will have a removable aluminum foil cover. We will record the time elapsed for half of the disks to float to the top in each container. |
| Conclusion | Our tentative conclusion is that the intermittent light test groups DID perform photosynthesis at a lower rate than our control group. However, we also noticed that test group 1 only needed 4mins of total light exposure compared to the control, which needed a little over 5 minutes of total light exposure to perform the same amount of photosynthesis. Perhaps this has something to do with the speed of the light reactions. They may continue for some period of time following the end of light exposure. However, since the light reactions occur at the rate of milliseconds, another explanation for the variation in the data may be linked to limitations in the accuracy of this technique in measuring oxygen productions during the light reactions. Ultimately, we suspect that the results we obtained with test group 2 are inaccurate, as we used an entirely different spinach leaf to create these disks. |
