AP BIOLOGY

Detailed explanation-1: -What is a photosystem? Photosynthetic pigments, such as chlorophyll a, chlorophyll b, and carotenoids, are light-harvesting molecules found in the thylakoid membranes of chloroplasts. As mentioned above, pigments are organized along with proteins into complexes called photosystems.

Detailed explanation-2: -It then transfers captured light from one pigment to the next as resonance energy, passing energy one pigment to the other until reaching the special chlorophyll a molecules in the reaction center. These special chlorophyll a molecules are located in both photosystem II and photosystem I.

Detailed explanation-3: -Photosystem I (PSI) has a P700 reaction centre containing chlorophyll that takes the electron and associated hydrogen donated from PSII to reduce NADP+ to NADPH.

Detailed explanation-4: -Within chloroplasts, photosystems I and II carry out the initial steps in photosynthesis by harvesting light energy and converting it to chemical energy. These photosystems are composed of protein subunits, chlorophyll, and cofactors.