AP BIOLOGY

Detailed explanation-1: -The light-dependent reactions use light energy to make two molecules needed for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH. In plants, the light reactions take place in the thylakoid membranes of organelles called chloroplasts.

Detailed explanation-2: -During photosynthesis light energy is used to split water, generating O2 and electrons that are then used to produce the ATP and NADPH required for carbon fixation.

Detailed explanation-3: -ATP and NADPH are used to convert the six molecules of 3-PGA into six molecules of a chemical called glyceraldehyde 3-phosphate (G3P). That is a reduction reaction because it involves the gain of electrons by 3-PGA. Recall that reduction is the gain of an electron by an atom or molecule.