The Effcts of Different Wavelengths on Leaf Pigments

Topics: Spectroscopy, Absorbance, Electromagnetic radiation Pages: 2 (420 words) Published: April 14, 2006
Introduction:
•Hypothesis: My hypothesis for this experiment, the study of the effects of different wavelengths on leaf pigments, if chlorophyll a absorbs blue-violet light, chlorophyll b absorbs blue light, carotene absorbs blue-green light, and xanthophyll absorbs blue light, then wavelengths of greatest absorption will be 400, 450, 500, and 450 respectively. •Independent Variable: Wavelengths

•Dependent Variable: optimum wavelengths of light for absorption •Standard Variable: method of measurement, what was measured •Predictions: Chlorophyll a absorbs best at a wavelength of 400, Chlorophyll b at 450, carotene at 500, and xanthophyll at 450. Materials & Methods:

•Experiment: First all the materials were gathered. Pigments were separated by chromatography paper. Pigments were loaded in a line on the paper. The paper was folded in a cylinder, stapled, placed in a cylinder with solvent, and sealed with wax paper until the pigments separated. After the pigments separated the paper was taken out to dry and the separated pigments were cut out. Four groups joined together to perform the remainder of the investigation. All of the groups' pigments were separated and put into separate test tubes. Acetone was added. Using forceps, the strips of chromatography paper were "washed" of their pigment. Lastly the absorption spectrum, the absorption pattern for a particular pigment, was measured. •Treatment: wavelengths of 400, 440, 480, 520, 560, 600, 640, 680, and 720 •Control: Acetone with no pigments

•Replication: This investigation did not institute replication •Materials: paper, writing utensils, capillary tube, leaf pigment extract in acetone, beakers, forceps, scissors, acetone, petroleum ether and acetone solvent, chromatography paper, wax paper, spectrophotometer, test tubes •Measurements: Absorption spectrum, percent transmittance to absorbance

Results: (See graph on page 2)

Discussion: My hypothesis for this experiment, if chlorophyll a absorbs...
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