Suppose there were plants that had a high concentration of Chlorophyll b, but lacked chlorophyll a, would it carry out photosynthesis? Then why do plants have chlorophyll b and other accessory pigments?
Green plants have different types of photosynthetic pigments like chl a, chl b, carotenoids and xanthophylls.All these photosynthetic pigments can absorb light.However, its chlorophyll a which act as the major photosynthetic pigment as they form the reaction centres named as Photosystem I and Photosystem II.Rest all of the pigments including chlorophyll b act as accessory photosynthetic pigment.These accessory pigments absorb light energy and transfers it to chlorophyll a.In absence of chlorophyll a, the photosystems will not function and photosynthesis will shut down.Thus, it is obvious that if any plant has high concentration of chlorophyll b and lacks chlorophyll a, then it cannot carry out photosynthesis.But the accessory pigments such as chlorophyll b, xanthophylls and carotenoids are also important because they absorb the light energy and direct it to the reaction center. Another importance lies in the fact that, xanthophylls and carotenoids prevent photo-oxidation of chlorophyll a and thus maintain the stability of the reaction center.
