Chlorophyll b is decomposed by chlorophyllase to form pheophytin b. This causes its color to change from green to olive brown. It is involved in the harvesting of light energy and its subsequent conversion into chemical energy during photosynthesis. Along with chlorophyll a, it plays a key role in the ability of plants to adapt to varying light intensities. The visible spectrum that is not absorbed when only chlorophyll a is present in the LHC.