(3)

PS II has an absorption maxima at 680 nm and is called $P_{680}$. In PS II, the reaction centre chlorophyll a absorbs 680 nm wavelength of red light causing electrons to become excited and jump into an orbit farther from the atomic nucleus.

(2)

In the light reaction of photosynthesis, ATP, NADPH, and oxygen are produced. NADPH participates in anabolic reactions (e.g., photosynthesis) that consume energy in order to build up larger molecules. NADH participates in catabolic reactions (e.g., respiration) that break down molecules to release energy.