What is the difference between an Absorption Spectrum and an Action Spectrum?
The absorption spectrum describes what wavelengths are absorbed and to what extent. The “Action” spectrum shows what wavelengths of light can actually be used to make photosynthesis work. These 2 spectra are not the same thing, but it is easy to confuse them. It is possible for the plant to absorb light without doing any photosynthesis. Other pigment molecules not involved with photosynthesis also absorb light. The action spectrum indicates that photosynthesis works best with light at of 420nm or light of 660nm. Part of your confusion probably comes from the fact that your 2 links say the same thing. Go down almost halfway on this page http://www.emc.maricopa.
