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A Spectrophotometric Analysis Of The Absorption Of Green Light Versus Red Light Absorption In Spinach Leaves

A Spectrophotometric Analysis of the Absorption of Green Light Versus Red Light Absorption in Spinach Leaves

The goal of the experiment was to determine if green light had less ability to absorb than red light in spinach leaves. This was done by separating the photosynthetic pigments (chlorophyll a, chlorophyll b, carotene and xanthophylls) from one another using paper chromatography. The separated pigments were then analyzed for their absorption spectrum using a spectrographometer. When the data was graphed it clearly showed the higher rate of red light absorption over green light. These results along with previous research indicate the importance of red light in photosynthesis and the minor role green light plays.

The majority of life on Earth depends on photosynthesis for food and oxygen. Photosynthesis is the conversion of carbon dioxide and water into carbohydrates and oxygen using the sun's light energy (Campbell, 1996). This process consists of two parts the light reactions and the Calvin cycle (Campbell, 1996). During the light reactions is when the sun's energy is converted into ATP and NADPH, which is chemical energy (Campbell, 1996). This process occurs in the chloroplasts of plants cell. Within the chloroplasts are multiple photosynthetic pigments that absorb light from the sun (Campbell, 1996).
Photosynthetic pigments work by absorbing different wavelengths of light and reflecting others. These pigments are divided into two categories primary (chlorophyll) and accessory (carotenoids) pigments. Chlorophyll is then divided into three forms a, b, and c (Campbell, 1996). Chlorophyll a is the primary pigment used during photosynthesis (Campbell, 1996). This pigment is the only one that can directly participate in light reactions (Campbell, 1996). Chlorophyll a absorbs the wavelengths of 600 to 700nm (red and orange) along with 400 to 500nm (blue and violet) and reflects green wavelengths (Lewis, 2004). Chlorophyll b has only a...