Cell Energy: Photosynthesis & Respiration Chapter 5, Section 1
In respiration energy is released fromsugars when electrons associated with hydrogen are transported to oxygen (theelectron acceptor), and water is formed as a byproduct. The mitochondriause the energy released in this oxidation in order to synthesize ATP. Inphotosynthesis, the electron flow is reversed, the water is split (not formed),and the electrons are transferred from the water to CO2 and in theprocess the energy is used to reduce the CO2 into sugar. Inrespiration the energy yield is 686 kcal per mole of glucose oxidized to CO2,while photosynthesis requires 686 kcal of energy to boost the electrons from thewater to their high-energy perches in the reduced sugar -- light provides thisenergy.
Cell Processes: Photosynthesis & Cellular Respiration
Environmental scientists recognize that the fundamental source of energy for most life on earth is the sun. Through photosynthesis, plants capture the light and convert it into chemical potential energy. Plants then store the potential energy in the form of (biological matter that fuels nearly every animal on earth).
The figure illustrates how closely photosynthesis and respiration are linked. As you can see, thanks to these two life-sustaining processes, plants and animals depend on each other to survive.