Question

The role of chlorophyll in photosynthesis is
A. Absorption of CO$_2$
B. Absorption of light
C. Absorption of light and photochemical decomposition of water
D. Absorption of water

Answer 1

Hint: A green colored pigment is found in chloroplast and these pigments remain embedded in the thylakoid membranes and form photosystems. These photosystems perform light-dependent
reactions and are associated with the splitting of water molecules.

Complete answer: Plants are eukaryotic and have membrane-bound organelles. They have plastids which are the site for the production and storage of important chemical compounds that are vital for autotrophic organisms. They also have pigment which is essential for the process of photosynthesis and different types of pigments in the plastids determine the color of the cell. Chloroplasts are the most known plastids and are involved in the process of photosynthesis. They are green color plastids and contain thylakoids filled with chlorophyll. Pigment protein complexes are known as photosystems that remain embedded in the thylakoid membranes of the chloroplasts. Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. PS-II captures sunlight and is associated with the water-splitting complex which splits water molecules to obtain electrons. Within the photosystem, enzymes capture photons of light to energize electrons that are then transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol that act as an electron carrier.
Hence, the correct option is (C)-Absorption of light and photochemical decomposition of water.

Note: Photosystem II performs light-dependent reactions. It is usually involved in non-cyclic photophosphorylation along with photosystem I and synthesize ATP and NADPH molecules. Whereas in photosystems I perform cyclic phosphorylation to produce ATP molecules only.