Photosynthetic pigments are found in certain proteins and absorb photons (waves of light) at particular wavelengths. This absorbance causes electrons in the pigments to become excited and they increase in energy level. Accessory pigments e.g. b-carotene (found in carrots and causing them to be orange) pass on this energy to primary pigments e.g. chlorophyll a, which lose an electron (become oxidised) to the electron transport chain in the Z-scheme.