Agriscience Foundation CFE Practice Exam

Light energy capture for photosynthesis is driven mainly by chlorophyll, the green pigment in plant chloroplasts. Chlorophyll absorbs blue and red wavelengths very well and uses that energy to excite electrons at the reaction centers of the photosystems, starting the light reactions that power ATP and NADPH formation. While chlorophyll is the primary light-harvesting pigment, other pigments such as carotene and xanthophyll extend the range of light absorbed and help protect the plant by dissipating excess energy. Betacyanin, by contrast, is not involved in photosynthesis; it appears in some tissues for coloration and doesn’t participate in capturing light energy for the process. Therefore, chlorophyll is the pigment mainly responsible for capturing light energy for photosynthesis.