(A) The mitochondrion converts energy from chemical fuels. (B) The chloroplast converts energy from sunlight. Inputs are light green, products are blue, and the path of electron flow is indicated by red arrows. Each of the protein complexes (orange) is embedded in a membrane. Note that the electron-motive force generated by the two chloroplast photosystems enables the chloroplast to drive electron transfer from H₂O to carbohydrate, and that this is opposite to the energetically favorable direction of electron transfer in a mitochondrion. Thus, whereas carbohydrate molecules and O₂ are inputs for the mitochondrion, they are products of the chloroplast.