AP BIOLOGY

Detailed explanation-1: -Absorption of light excites an electron to a higher energy state, thus converting the energy of sunlight to potential chemical energy. The photosynthetic pigments are organized into photocenters in the thylakoid membrane, each of which contains hundreds of pigment molecules (Figure 10.20).

Detailed explanation-2: -Light energy is harnessed in Photosystems I and II, both of which are present in the thylakoid membranes of chloroplasts.

Detailed explanation-3: -But what happens to the electrons in these photosystems? Light first hits photosystem II, and its energy is absorbed by the pigments within this photosystem. This excites the electrons, and they move to a higher energy level. The electrons then exit the photosystem and move down the electron transport chain.

Detailed explanation-4: -Photosystem I and photosystem II are the two multi-protein complexes that contain the pigments necessary to harvest photons and use light energy to catalyse the primary photosynthetic endergonic reactions producing high energy compounds.

Detailed explanation-5: -There are two types of photosystems in the light-dependent reactions, photosystem II (PSII) and photosystem I (PSI).