text: compare and contrast photosynthesis and respiration?   aight here goes  in a nutshell, the comparison is that they both produce chemical energy in the form of atp (adenosine triphosphate), the difference is that in cellular respiration glucose and oxygen are used up and carbon dioxide and water are produced, and in photosynthesis, light and water and carbon dioxide are used and oxygen and glucose are produced.  a little more in depth, heres the description of both cellular respiration - occurs in the mitochondria, first a glucose molecule goes through glycolysis, which produced 2 molecules of atp and 2 molecules of pyruvate or pyruvic acid - each one of those either enters the crebs cycle and the electron transport chain, or if there isnt enough oxygen it goes into lactic acid cycle - which doesnt produce much energy and produced lactic acid (runners get this and the lactic acid causes muscle soreness), but anyway if there is enough oxygen, the pyruvate goes into the krebs cycle, in it a bunch of things happen to the pyruvate to turn it into different things, ending up in citric acid (krebs cycle is also called citric acid cycle), the krebs cycle produced some more atps and other molecules called nadph and fadph, after that it enters the stage that produces the most energy the electron transport chain - in this an electron is transported through a bunch of proteins called cytochromes and during this transport protons (h+ ions) are produced, they create a ph gradient between the sides separated by the cristae (inner wall of the mitochondria), and these ions travel through proteins that they call atp synthease, while doing that they cause atp to be made from adp and inorganic phosphate. the electron transport chain produces 28 atp molecules, giving the whole cycle a total of 32 atp from one glucose molecule.  photosynthesis - occurs in the chloroplast, first light hits an electron in photosystem ii, that excites the electron and it goes through an electron transport chain to reach photosystem i, during which it produces energy same way that the etc in respiration does, after that the electron gets hit by light again this time in photosystem i, it gets excited again ang goes through another etc, producing some more atp as well as nadph.  these molecules are then used in the calvin cycle, in which carbon dioxide is absorbed by the plant from the air and used to form 3 carbon sugars which are then combined to form glucose, oxygen is released as a byproduct of that.   hope that helps