AP BIOLOGY

Detailed explanation-1: -When light energy is absorbed by pigments and passed inward to the reaction center, the electron in P700 is boosted to a very high energy level and transferred to an acceptor molecule. The special pair’s missing electron is replaced by a new electron from PSII (arriving via the electron transport chain).

Detailed explanation-2: -Light energy causes the excitation and loss of an electron from a PSII reaction center chlorophyll (P680). Water is oxidized to replace the lost electron, generating H+ ions and oxygen (O-2) ions. These O-2 ions combine to form the diatomic O2. The excited electron is boosted to a higher energy state.

Detailed explanation-3: -As electrons are passed down the chain, they move from a higher to a lower energy level, releasing energy. Some of the energy is used to pump H +start superscript, plus, end superscript ions, moving them out of the matrix and into the intermembrane space. This pumping establishes an electrochemical gradient.

Detailed explanation-4: -The many pigment molecules in each photocenter act as antennae to absorb light and transfer the energy of their excited electrons to a chlorophyll molecule that serves as a reaction center. The reaction center chlorophyll then transfers its high-energy electron to an acceptor molecule in an electron transport chain.

Detailed explanation-5: -As the electron from the electron transport chain arrives at photosystem I, it is re-energized with another photon captured by chlorophyll. The energy from this electron drives the formation of NADPH from NADP+ and a hydrogen ion (H+).