Minutes | Dark | 24 cm | 30 cm | 49 cm |
0 | 0.802 | 0.917 | 0.914 | 0.913 |
5 | 0.675 | 0.17 | 0.098 | 0.122 |
10 | 0.633 | 0.116 | 0.055 | 0.15 |
15 | 0.69 | 0.199 | 0.214 | 0.179 |
20 | 0.641 | 0.105 | 0.055 | 0.129 |
25 | 0.713 | 0.397 | 0.18 | 0.272 |
30 | 0.681 | 0.112 | 0.027 | 0.158 |
This experiment tested the effect of light intensity on the electron transport chain. The hypothesis was that with increased light intensity, absorbance would decline. To test this hypothesis there were 5 test tubes. All tubes were filled with 05 ml of chloroplast and 3 ml of 0.1 M PO4 buffer. Test tubes 1 through 4 were also filled with 400 μl of DPIP and 100 μl of water. The DPIP was not added into any of the test tubes until right before the initial readings were taken to ensure an accurate reading of the reaction taking place. The 5th test tube was the blank and it contained no DPIP, so a reaction would not take place, and 500 μl of water to substitute for the lack of DPIP. The blank was kept in room light, test tube one was wrapped in foil to ensure that no light entered the tube, test tube two was 24 cm from the light source, test tube 3 was 30 cm from the light source and test tube 4 was 49 cm from the light source. The absorbance was measured at 600 nm and taken every 5 minutes. The data we collected showed that the absorbance was highest in the dark test tube which agreed with our hypothesis. For the other three test tubes all of the absorbance measurements were very similar. The experiment did prove that absorbance values decreased with photosynthetic activity. When the light intensity was low, photosynthesis increased but at higher light intensities photosynthesis levels off.
This experiment tested the effect of light intensity on the electron transport chain. The hypothesis was that with increased light intensity, absorbance would decline. To test this hypothesis there were 5 test tubes. All tubes were filled with 05 ml of chloroplast and...