Photosynthesis: Light and Life

Complex life on Earth requires oxygen as the terminal electron acceptor in the respiratory chain. However, the lifetime of a single oxygen molecule in the atmosphere is only 4500 years. Oxygen is continually being replenished by the action of photosynthetic organisms, using the only substantial energy input to the Earth, sunlight. How this light energy is harvested and used is of fundamental biological importance, and may be of crucial importance in developing sustainable energy technologies.