- Chloroplast = organelle cotaining photosystem (where photosynthesis occurs).
- A photosystem consists of:
- chlorophyll molecules (primary pigment)
- accessory pigments (chrolophyll b and carotenoids)
PS I (photosystem I) absorbs light of wavelength 700nm
PS II (photosystem II) adsorbs light of wavelength 680nm
Paper chromatography technique = to separate different pigments of a leaf.
Each pigment is identified by the characteristic coloured peak formed on the chromatography paper.
The amount of absorption of the pigments and the rate of photosynthesis at different wavelength of light can be graphically represented.
Absorption spectrum = indicates the amount of absorption at different wavelengths of light.
Action spectrum = indicates the rate of photosynthesis at different wavelengths of light.
Engelmann concluded from the experiments that photosynthesis can occur only when the chloroplasts are illuminated by red and blue light