5 Differences between Absorption Spectrum and Action Spectrum

Photosynthetic pigments absorb light only in the visible region of the spectrum (390nm-760nm).The action spectrum peak of chlorophyll is almost same as that of absorption spectrum indicating that chlorophyll is the primary pigment in photosynthesis.

                                       Absorption Spectrum vs Action Spectrum

Absorption Spectrum	Action Spectrum
Absorption Spectrum is the graphic representation of the different wavelengths of light absorbed by the different pigments in a leaf during photosynthesis	Action Spectrum is the graphic representation of the effectiveness of different wavelengths of light in photosynthesis
Plot showing intensity of light absorbed relative to its wavelength	Plot showing relative efficiency of photosynthesis produced by light of different wavelengths
Explains the relationship between quality of light and absorbing capacity of pigments	Explains the relationship between photosynthetic activity in relation to different wavelengths of light
Chlorophyll absorb blue and red light Carotenoids absorb violet and blue light	The maximum photosynthesis occurs in blue and red light
Absorption of different wavelengths of light by pigments can be measured using spectrophotometer.	In action spectrum, the rate of photosynthesis is measured as amount of carbon dioxide fixation, oxygen production, NADP+ reduction etc.