Pigments involved in Photosynthesis – Class 11 | Chapter – 13 | Biology Short Notes Series PDF

Pigments involved in Photosynthesis: Photosynthetic organisms contain light-absorbing molecules called pigments. These photosynthetic pigments absorbs only specific wavelengths of visible light while reflecting others. The set of wavelengths absorbed by a pigment is its absorption spectrum.

Different photosynthetic organisms have a variety of different pigments, so they can absorb energy from a wide range of wavelengths.

Pigments involved in Photosynthesis


  • The photosynthetic plants have a primary light-absorbing pigment known as chlorophylls.
  • Chlorophyll is a water-insoluble magnesium porphyrin compound.
  • It can absorb light at a wavelength below 480 nm and between 550 and 700 nm.
  • As white sunlight falls on a chlorophyll layer, the green light with a wavelength between 480 and 550 nm is not absorbed but is reflected which is why plant chlorophylls and whole leaves are green.
  • Chlorophyll always occurs bound to proteins.
  • It is a green pigment with polycyclic and planar structure.
  • Chlorophyll is formed from proto-chlorophyll in the light. Addition of two H-atom to protochlorophyll gives chlorophyll.


  • It is a bluish green colored pigment with molecular formula C55H72O5N4Mg.
  • In reflected light chl-a shows blood red color while in transmitted light, it shows blue green light.
  • It is an universal pigment in all photosynthetic organism except bacteria.


  • It is a yellowish green color pigment with molecular formula C55H70O6N4Mg.
  • It appears dull brown in reflected light and yellowish green color in transmitted light.
  • Chl-b is absent in green algae, brown algae, red algae, diatoms, etc.


  • They are secondary light-absorbing pigments or accessory pigments occurring in the thylakoid membranes.
  • They may be yellow, red, or purple colored pigments. The yellow colored carotenoids are lutein while red-orange is β-carotene
  • The carotenoid pigments absorb light at wavelengths which are not absorbed by the chlorophylls so they are supplementary light receptors.
  • There are 2 types of carotenoids; carotenes and xanthophylls.
  • Carotene is in orange color while xanthophylls are yellow in color.
  • These accessory pigments protect the chlorophyll against photo-oxidation and then transfer light energy to chlorophylls.
  • It also helps in preventing photodynamic damage.
  • Also, carotenoids are able to express themselves in mature leaves even if chlorophyll begins to disintegrate.


  • These are open chain tetra pyrroles which lacks Mg++ and the pytol tail.
  • Green algae and red algae posses phycobilins such as phycoerythrobilin and phycocyanobilin respectively as their light-harvesting pigments.
  • Phycobilins are covalently linked to specific binding proteins, forming phycobiliproteins, which associate to form highly ordered complexes called phycobilisomes that constitute the primary light-harvesting structures in the microorganisms like green algae and red algae
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By Team Learning Mantras