AP BIOLOGY

Detailed explanation-1: -The primary function of the light-dependent reactions is to convert light energy into chemical energy. This chemical energy (ATP and NADPH) will be used by the Calvin cycle (light independent reaction) to fuel the assembly of sugar molecules.

Detailed explanation-2: -The ATP and NADPH from the light-dependent reactions are used to make sugars in the next stage of photosynthesis, the Calvin cycle. In another form of the light reactions, called cyclic photophosphorylation, electrons follow a different, circular path and only ATP (no NADPH) is produced.

Detailed explanation-3: -ATP and NADPH are energy storage and electron carrier/donor molecule. Both ATP and NADPH are used in the next stage of photosynthesis. The chlorophyll molecule regains the lost electron from a water molecule through a process called photolysis, which releases dioxygen (O2) molecule.

Detailed explanation-4: -In the second stage, ATP and NADPH are used to convert the 3-PGA molecules into molecules of a three-carbon sugar, glyceraldehyde-3-phosphate (G3P). This stage gets its name because NADPH donates electrons to, or reduces, a three-carbon intermediate to make G3P.

Detailed explanation-5: -High-energy electrons form when pigments in photosystem II absorb light. The electrons ► pass through electron transport chains, a series of electron carrier proteins. The movement of electrons through an electron transport chain causes a thylakoid to fill up with hydrogen ions and generates ATP and NADPH.