Testing a leaf for starch experiment

Observation:

        The green leaf left a green solution in the ethanol while the yellow leaf left it with a pale yellow color. Both leaves were colorless after they were taken out of the ethanol but when the iodine solution was added to them respectively only the green leaf turned blue-black while the yellow leaf took the iodine’s brick red color.

Conclusion:

        From the experiment we can now conclude starch and chlorophyll were present in the same place. The green leaf which contained chlorophyll tested positive for starch while the yellow leaf containing no chlorophyll tested negative for starch.

Discussion:

        Photosynthesis is the process whereby chlorophyll uses sunlight to produce glucose which is then converted to starch.

        The leaf was placed in hot water to remove the waxy covering (the cuticle), and to break the cell membrane, and stopping all chemical processes. Since chlorophyll dissolves in ethanol (solvent), the leaves were placed in the ethanol and boilt so they could be decolorized and was then rinsed to remove any ethanol in it so that when the iodine solution is added it does not react with it.

        The green leaf turned blue-black when the iodine solution was added to it because it contained chlorophyll and was able to produce starch while the yellow leaf took the color of the iodine solution because it did not contain chlorophyll so it was unable to produce starch hence there was no reaction with the solution.