photosynthesis - under the right conditions to show any...

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Dan Morgan Observing Photosynthesis through Absorbency Levels It can be determined from the results that tube or group 1, with its lack of chloroplasts and being placed in the dark, showed very little change in its absorbance at 600 nanometers. Similarly, when a tube has no chloroplasts and placed in a dim light its absorbance stays very constant and unchanging, visible to the naked eye as not changing in color. The presence of the artificial electron acceptor 2,6-dichlorophenolindophenol, or DCPIP, had very little affect on these two tube’s ability to perform photosynthesis it can be concluded, because of a lack of chloroplasts. The addition of a chloroplast as is present in the final seven tubes enables the possibility of photosynthesis to occur given the right conditions and lack of inhibitors. In trials four through seven the absorbency of the increasing numbered tubes decreases dramatically. Tube three, which starts out with an absorbency rate of .85 and ends at .86 is the only tube under the right
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Unformatted text preview: under the right conditions to show any sort of increase, however minimal it might be. From tube four to seven, the amount of decrease of absorbency increases with each tube’s passing. Tube four falls from .7 to .68, tube five falls from .9 to .67, tube six from 1.1 to .62 and finally tube seven falls from 1.6 to .62, the largest decrease in absorbency observed. This can be attributed to the different amount of light presented to the tubes which all had the same chloroplast and DCPIP present. In tubes eight and nine, the effects of herbicides present in the solution of chloroplasts and DCPIP were tested. The conditions were no light and little light, accordingly, and therefore showed very little signs of change and in fact did not change in absorbency level over the period of thirty minutes. This results from the pesticide 3-(3,4-dichlorophenyl)-1,1-dimethylurea, or DCMU, effectively stopping the flow of electrons by inactivating Photosystem II....
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This lab report was uploaded on 04/07/2008 for the course ZOO 116 taught by Professor Dr.russell during the Spring '08 term at Miami University.

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