Question

Chemical which absorbs light energy and changes it to chemical energy is

• A. Xanthophyll
• B. Chlorophyll a
• C. Chlorophyll b
• D. Chlorophyll c

Answer 1

The correct option is B Chlorophyll a

Light energy is converted to chemical energy when a photochemically excited special chlorophyll molecule of the photosynthetic reaction centre loses an electron, undergoing an oxidation reaction. In the light reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, allowing the start of a flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP to NADPH. In addition, this creates a proton gradient across the chloroplast membrane; its dissipation is used by ATP synthase for the concomitant synthesis of ATP. The chlorophyll molecule regains the lost electron from a water molecule through a process called photolysis, which releases the dioxygen (o2) molecule.

So, the correct option is 'Chlorophyll a'.