Photosynthetic pigments An overview of the pgiments used in phtosythesis. 3.5 / 5 based on 2 ratings ? BiologyCellular processes and structureA2/A-levelAQA Created by: Marianne BradleyCreated on: 21-10-10 08:43 How light arrives at the plant As sunlight falls on the plant, some wavelengths are absorbed. The others are reflected/transmitted. Pattern of absorption/reflection: dependent on the pigments. 1 of 4 Chlorophyll and other photosynthetic pigments. 2 of 4 How chlorophyll harnesses energy from sunlight Light harnessed by a photosynthetic pigment behaves as PHOTON PARTICLES. A QUANTUM is the fixed amount of energy that a photon contains. The shorter the wavelength the larger the photon. When a photon is absorbed the pigment's electrons gain energy, and are raised to a higher energy level. This makes the molecule very unstable. In a chloroplast the energy is passed to a PRIMARY ACCEPTOR MOLECULE. Molecule: reduced. Chlorophyll: oxidised. 3 of 4 Arrangement of pigments in the chloroplast. Pigments clustered in the thykaloid membranes. Cluster called an ANTENNA COMPLEX. Light energy is channeled to just one molecule of chlorophyll a. Chlorophyll a and primary acceptor molecule: REACTION CENTRE. Reaction centre + light gathering molecules = photosystem. Photosystem 1 = P700. Chlorophyll a's maximum absorption. Photosystem 2 = P680. LIGHT DEPENDENT stage. 4 of 4
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