• An?absorption spectrum?is a graph that shows the?absorbance?of different wavelengths of light by a particular pigment
• Chlorophylls?absorb wavelengths in the?blue-violet and red regions?of the light spectrum
• Carotenoids?absorb wavelengths of light mainly in the?blue-violet region?of the spectrum

Absorption spectra of chlorophyll A, chlorophyll B and carotenoid pigments

• An?action spectrum?is a graph that shows the?rate of photosynthesis?at different wavelengths of light
• The rate of photosynthesis is?highest?at the?blue-violet?and?red?regions of the light spectrum, as these are the wavelengths of light that plants can?absorb?(ie. the wavelengths of light that chlorophylls and carotenoids can absorb)

Photosynthetic action spectrum

• There is a strong?correlation?between the cumulative absorption spectra of all pigments and the action spectrum:
  • Both graphs have?two main peaks?– at the?blue-violet?region and the?red?region of the light spectrum
  • Both graphs have a?trough?in the?green-yellow?region of the light spectrum

An overlay of the photosynthetic absorption and action spectra shows there is a strong cumulative correlation