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Abstract
Chlorophyll is a natural pigment found in green plants. It is the primary pigment that absorbs light energy from the sun for photosynthesis. This energy is then used by the plant to synthesize glucose from carbon dioxide and water. Chlorophyll in the leaves of plants can be extracted and separated using chromatography. A good source of chlorophyll for an extraction is a dark green leafy vegetable like spinach. Rub a fresh spinach leaf on the bottom of a strip of filter paper. You can get a good dark smear of green by using a coin. When you see a dark line of chlorophyll, dip the bottom of the strip into a solvent like rubbing alcohol or acetone (nail polish remover). What happens to the chlorophyll? Are there other pigment molecules in the leaf? What would happen to leaves collected during other seasons? Try an experiment to compare different colors of fall leaves: green yellow orange and red. Some species of trees and bushes have red or yellow leaves all year round. What would their pigment and chlorophyll molecules look like after being separated? What about the difference in chlorophyll levels between young leaves and old leaves? The young leaves will be at the tip of the stem, while older leaves will be at the base of the stem near the branch. What happens to the chlorophyll in leaves that have been blocked from sunlight? You can use dark paper and tape or a paper lunch bag to cover a leaf and block out the sunlight. Will this change the chlorophyll components of the leaf? What can these experiments tell you about the regulation of chlorophyll production in plants? (VanCleave, 1993, 107–112; Science Buddies, Paper Chromatography: Advanced Version 2)Bibliography
VanCleave, J. 1993. Janice VanCleave's A+ Projects in Biology. New York, NY: John Wiley & Sons, Inc.Variations
Last edit date: 2008-11-11 12:21:34
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