AP BIOLOGY

Detailed explanation-1: -The light reactions of photosystems I and II (PSI and PSII) result in the formation of an electrochemical transmembrane proton gradient that is used for the production of ATP.

Detailed explanation-2: -The key difference between both the photosystems – Photosystem I and photosystem II is that PS I tends to absorb light of longer wavelengths > 680nm, whereas PS II absorbs light of shorter wavelengths <680 nm.

Detailed explanation-3: -The oxygen-evolving center of photosystem II is a complicated cluster of manganese ions (magenta), calcium (blue green) and oxygen atoms (red). It grips two water molecules and removes four electrons, forming oxygen gas and four hydrogen ions.

Detailed explanation-4: -This is accomplished by the use of two different photosystems in the light reactions of photosynthesis, one to generate ATP and the other to generate NADPH. Electrons are transferred sequentially between the two photosystems, with photosystem I acting to generate NADPH and photosystem II acting to generate ATP.