Role of Light in photosynthesis:

Sunlight energy is absorbed by chlorophyll. It is then converted into chemical energy, which drives the photosynthetic process. Not all the light falling on the leaves is absorbed. Only about one percent of the light falling on the leaf surface is absorbed, the rest is reflected or transmitted.

The light rays of different wavelengths are not only differently absorbed by photosynthetic pigments but are also differently effective in photosynthesis. The blue and red lights carry out more photosynthesis.

The function of Chlorophyll:

When chlorophyll absorbs light, its electrons are excited and they leave a chlorophyll molecule. The excited electrons are passed through the electron transport chain and their energy is captured for the formation of ATP and for reducing NADP to NADPH.

Role of Chlorophyll in photosynthesis:

The photosynthetic pigments are organized in the form of clusters, called photosystems, in thylakoid membranes of chloroplasts. Chlorophyll-a is the main photosynthetic pigment.

Others are called accessory pigments and include Chlorophyll-b and carotenoids. Chlorophylls absorb mainly blue and red lights. Some wavelengths not absorbed by chlorophyll 'a' are very effectively absorbed by accessory pigments and vice-versa.