Chlorophyll-a molecules act as antenna molecules. They get excited by absorbing light and emit electrons during cyclic and non-cyclic photophosphorylations. They form the reaction centres for both photosystems I and II. Chlorophyll-b and other photosynthetic pigments such as carotenoids and xanthophylls act as accessory pigments. Their role is to absorb energy and transfer it to chlorophyll-a. Carotenoids and xanthophylls also protect the chlorophyll molecule from photo-oxidation. Therefore, chlorophyll-a is essential for photosynthesis.
If any plant were to lack chlorophyll-a and contain a high concentration of chlorophyll-b, then this plant would not undergo photosynthesis.
Define a taxon. Give some examples of taxa at different hierarchical levels.
What are the steps involved in formation of a root nodule?
Describe the structure of the following with the help of labelled diagrams.
(i) Nucleus
(ii) Centrosome
What is the difference between lymph and blood?
How do you distinguish between a skeletal muscle and a cardiac muscle?