BISC120 - Photosynthesis Lab Report

BISC120 - Photosynthesis Lab Report - Chlorophyll and...

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Chlorophyll and Photosynthesis: Methods In order to identify the necessity of chlorophyll for photosynthesis, we administered an experiment testing for starch in green parts and non-green parts of leaves. Since glucose can be transported by different parts of the leaves, we test for the presence of starch to verify photosynthetic processes. And since the chlorophyll pigment is green, we can easily pinpoint parts of leaves that have chlorophyll by simply observing their pigment. For the first part of this experiment, we obtained a variegated leaf from Coleus plant (Figure 1). We cut this leaf in half by the midrib. The first half was used for a starch test. We boiled this leaf in a 250 ml beaker filled one-third with water for three minutes to rupture the cells. Meanwhile we boiled the alcohol by placing the beaker in a hot water bath. We then transferred it to a 100ml beaker one-third full of alcohol and boiled it for another five minutes to extract the chlorophyll. We then transferred the leaf to a petri dish where we covered it in iodine solution for 3 minutes. We rinsed with water and examined it for starch presence, which would be denoted by a dark brown or black color. The second half of the leaf was used to test for presence of glucose. We separated the half leaf into green and white. We then cut up these pieces and put them into separate test tubes filled with 2ml water. We boiled these tubes in a water bath for five minutes to extract any glucose. We then emptied the liquid into a separate tube, in which we added five drops of Benedict’s solution to test for glucose. We then put these tubes back into the water bath for five minutes. Any light green, yellow, or orange coloration indicated glucose. The same process was repeated to test for starch and glucose test in the green
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corn leaf, illustrated in Figure 3. Results
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This note was uploaded on 07/20/2011 for the course BIO 120 taught by Professor Staff during the Spring '07 term at USC.

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BISC120 - Photosynthesis Lab Report - Chlorophyll and...

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