The experiment consisted of using a spectrophotometer to determine the ability

The experiment consisted of using a spectrophotometer to determine the ability of a pigment to absorb different wavelengths of light in chlorophyll extract.  An absorbance graph was to be made and the hypothesis was that the spectrum graph of chlorophyll would have a dip in the green area since the green pigment will be reflected.  Using alcohol as the control and chlorophyll extract as the test subject, both materials were placed into a spectrophotometer and wavelength pigments were determined between 400 and 700.  Results obtained were lower numbers in the green region and had higher numbers in the blue and red region.  Therefore, that is proof that chlorophyll reflects the green wave lengths between 490 and 590.  Also, the best absorption of light by chlorophyll is in the red, blue and violet waves.

Introduction

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Photosynthesis is the way plants produce food.  There are two stages of photosynthesis.  First, the light cycle converts light energy to chemical energy.  Secondly, the Calvin cycle uses the chemical energy from the light reactions to make sugar.  Light travels in wavelengths that range from 380 nm to 760 nm.  Pigments are substances that absorb visible light.  Different pigments absorb different wavelengths of the light (See Table 1).  Wavelengths that are absorbed disappear and wavelengths that are reflected are seen.  Plants with chlorophyll appear green since the green wavelengths are reflected and not absorbed.  Therefore, the greatest absorption should be in the red, blue, and violet wavelengths.  Chlorophylls a and b can absorb a maximum of 600-675 and 400-475 nm ranges and will absorb light in two regions of the spectrum.  To test the absorption of pigments a spectrophotometer is used.  A graph called an absorption spectrum plots the pigment’s light absorption versus the wavelength.