Photosynthesis has two reactions: Light reactions and Dark reactions (The Calvin Cycle). During the light reaction, photosynthesis usually (but not always) goes through an electron transport chain. This is a noncyclic pathway that begins with photosystem II (PSII). During PSII, solar energy is absorbed, passed to the b6f complex, and then passed to photosystem I (PSI). The electrons become energized and go to NADP reductase. Here, NADP+ is reduced to NADPH. The electrons then go to ATP synthase to make ATP, which is used in the Calvin Cycle to make oxygen. Oxygen is then given off, so animals receive it. Cellular respiration has 4 stages: Glycolysis, the prep reaction, the krebs cycle, and the electron transport chain. ATP is used in every stage to produce more ATP. Glycolysis produces 2 ATP, the prep reaction produces 0 ATP, the Krebs cycle produces 2 ATP, and the electron transport chain produces 32-34 ATP. This energy is then used by the cell to perform cellular processes.
