DENDROLOGY

Detailed explanation-1: -P680 is composed of chlorophyll a molecule which, after excitation by the absorption of light to form P680*, gives up an electron to an acceptor, converting it to P680•+.

Detailed explanation-2: -The reaction center chlorophyll (or the primary electron donor) of photosystem II that is most reactive and best in absorbing light at wavelength of 680 nm.

Detailed explanation-3: -When the P680 special pair of photosystem II absorbs energy, it enters an excited (high-energy) state. Excited P680 is a good electron donor and can transfer its excited electron to the primary electron acceptor, pheophytin.

Detailed explanation-4: -Each photosystem has their own characteristic reaction center that absorbs light at specific wavelengths. Photosystem II is known as P680 because it absorbs light best at 680 nm (the red part of the spectrum). Photosystem I is known as P700 because it absorbs light best at 700 nm (the far red part of the spectrum).

Detailed explanation-5: -PSII uses light energy to excite a special pair of chlorophylls, known as P680 due to their 680 nm absorption peak in the red part of the spectrum.