Photosynthetic Activity
The light receiving photosynthetic pigments in the plant are at the thylakoid membrane in the chloroplasts. The most common pigment in his quantity and is present in all green plants and alga is ‘Chlorophyll a’. Other pigments are called secondary pigments and include ‘Chlorophyll b’ and carotenoids. To every photosynthetic pigment a typical absorption spectrum, meaning a different absorption ability of light in different wavelengths.
Chlorophyll a – 420nm, 663nm
Chlorophyll b – 453nm, 645nm
Carotenoids – 420nm-480nm
The light receiving pigments array constructs a type of antenna that is used to transfer light energy to the reaction center (Chlorophyll a), which drives the light process in Photosynthesis. The quantitative ratio of different chlorophylls varies in different plants, organs at the same plant, different exterior conditions and different periods.
- Chlorophyll absorption - - - - - - - - - - - - - - - - Photosynthesis activity -
The absorption by the chlorophyll is mainly obvious in the red and blue-violet area, although absorption lines in other areas do exist. Chlorophylls a and b are separated by the wavelength at which maximum absorption occurs. The absorption lines of Chlorophyll a at both the blue and red ends of the spectrum are farther away than the absorption lines of Chlorophyll b. Chlorophyll quantities in a green leaf vary between 0.05%-0.2% of the fresh weight. The ratio between Chlorophyll a and Chlorophyll b is 2.5/1=a/b, although it is not permanent because Chlorophyll a is more easily destroyed, meaning the quantitative ratio varies under different conditions.