ICSE Class 10 Answered

The phenomenon of light capture for photosynthesis is enhanced by a network of pigments arranged in aggregates called antennae complexes in chloroplasts. The energy transduction step of photosynthesis begins when chlorophyll absorbs a photon in the blue or red part of the visible spectrum. When absorption occurs, the energy in the photon is transferred to an electron in the chlorophyll molecule. The electron is raised to an excited state equivalent to the energy in the photon. If the electron is allowed to fall back to the ground state, energy is emitted as light and heat. However, in photosynthetic organisms, the energy in the excited electron is transferred to a chlorophyll molecule that acts as the reaction centre. Here, the high-energy electron is transferred to an electron acceptor, which becomes reduced. In this way, light energy is transduced to chemical energy.