AP BIOLOGY

Detailed explanation-1: -The electron lost from the chlorophyll a special pair is replenished by splitting water. The passing of the electron in the first part of the electron transport chain causes protons to be pumped from the stroma to the thylakoid lumen.

Detailed explanation-2: -After light excites the electron and they leave Photosystem II to travel down the first electron transport chain, how are these electrons replaced to Photosystem II? Oxygen is reduced and the electrons are given to the chlorophyll molecules of photosystem II.

Detailed explanation-3: -The electrons then exit the photosystem and move down the electron transport chain. As electrons move from one component to the next, they release energy. The electrons that have left photosystem II need to be replaced, and these electrons are provided by the photolysis of water.

Detailed explanation-4: -From photosystem II, electrons are carried by plastocyanin (a peripheral membrane protein) to photosystem I, where the absorption of additional photons again generates high-energy electrons. Photosystem I, however, does not act as a proton pump; instead, it uses these high-energy electrons to reduce NADP+ to NADPH.

Detailed explanation-5: -These O-2 ions combine to form the diatomic O2. The excited electron is boosted to a higher energy state. Electrons are passed from a photosystem into a redox or electron transport chain, eventually attaching to a chlorophyll molecule in Photosystem I (P700).