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Chlorophyll molecules are essential for photosynthesis and allow plants, some fungi, and some bacteria to capture free energy from light and convert it into chemical energy.

An absorption spectrum illustrates the amount of light energy absorbed across a range of wavelengths, and the graph below represents the absorption spectra of chlorophyll a and chlorophyll b pigment molecules in a plant cell.

"Chlorophyll Ab Spectra." Wikipedia. Wikimedia Foundation, n.d. Web. 06 Feb. 2016.

The relative absorption rates of chlorophyll a and chlorophyll b indicate that


blue light would provide for the highest rate of photosynthesis, producing glucose in plant cells at a faster rate than other wavelengths of light.


both chlorophyll a and chlorophyll b will drive the highest rate of photosynthesis between 500 nm - 600 nm, which explains why green light is the ideal light source for plants.


chlorophyll b absorbs only blue light and chlorophyll a absorbs only red light, and natural selection has favored photosynthetic systems that do not use all the visible light wavelengths because this would provide too much energy to the organism.


relative rates of photosynthesis are constant across the range of range of visible light wavelengths, as this ensures that plants and other autotrophs can convert free energy into glucose at a constant rate.

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