An absorption spectrum is a graph showing the percentage of light absorbed by
pigments, for each wavelength of light.
An example is the absorption spectrum of chlorophyll a and b.
The best absorption is seen with violet-blue light.
There is also good absorption with red-orange light.
Most of the green-yellow light is reflected and therefore not absorbed. This
wavelength of light shows the least absorption.
The action spectrum of photosynthesis is a graph showing the rate of
photosynthesis for each wavelength of light. The rate of photosynthesis will not be the
same for every wavelength of light.
The rate of photosynthesis is the least with green-yellow light (525 nm-625 nm).
Red-orange light (625nm-700nm) shows a good rate of photosynthesis.
The best rate of photosynthesis is seen with violet-blue light (400nm-525nm).
The wavelengths that is does not absorb are reflected from it.
Chlorophyll Is the main pigment contained in chloroplasts. It looks green because it
reflects green light. Other wavelengths (colours) of light are absorbed.
llle diagram shows the wavelengths of light absorbed by the various pigments found
in chloroplasts. These graphs are called absorption spectra.
If we shine light of various wavelengths on chloroplasts containing different pigments,
we can measure the rate at which they give off oxygen. These graphs are called action
spectra.