Question

Describe the travels of electrons in photosynthesis and the travels of electrons in cell respiration.

Answer 1

Electron transport in photosynthesis

Photosynthetic electron transport chain consist of photosystem 1 and photosystem 2. Reaction starts when light energy strikes on reaction centre P680 of photosystem 2. In the excited state they transfer electrons to primary electron acceptor .later this electrons passes through stable carriers.

In photosystem 2 primary electron carrier is pheophytin . Then electron passes to carriers quinones, plastoquinone, cytochrome b ,plastocyanin . Then electron transfer to reaction centre P700 of photosystem 1. When P700 get excited electrons transport to ferredoxin through iron sulfur protein. 2 ferredoxin molecule transfer one electron each to NADP+ to form NADPH.

Cellular respiration also known as aerobic respiration. Electron transport chain is the final stage of aerobic respiration. This stage provide ATP. Carrier proteins are found in inner membrane of mitochondria. H+ ions and electrons are released by NADH. FADH also release electrons to the transport chain. These flow of ions (H+ and electrons) across membrane helps in production of ATP. ATP synthase is the enzyme help in ATP production. Final acceptor of H+ and electron is oxygen. Oxygen combines with these ions to form water.