Light Dependent Reactions in Photosynthesis

What is the role of photosystems in the light dependent reactions of photosynthesis?

Which wavelength corresponds to the absorption maximum of Photosystem II?

What happens to Photosystem II during the light dependent reactions?

Which molecules are primarily found in the reaction center of a photosystem?

What process occurs as electrons pass through the electron carriers from PSII to PSI?

Light Dependent Reactions (Hill Reactions)

Photosynthesis' light-dependent reactions rely on pigments absorbing light energy.
Pigments are organized into photosystems (two types) within the thylakoid membrane.
Photosystems comprise:
- An antenna/light-harvesting complex, collecting light energy.
- A reaction center, containing special chlorophyll a molecules. These chlorophyll a molecules release highly energized electrons for further reactions.
Photosystem II (P680/P690):
- Discovered second, but functions first in the light-dependent reactions.
- Absorbs light maximally at 680-690nm wavelengths.
Photosystem I (P700):
- Discovered first.
- Absorbs light maximally at 700nm wavelengths.
Light energy excites electrons in both photosystems (from chlorophyll a in the reaction center).
Excited electrons are transferred to electron carriers within the thylakoid membrane.
Electrons passing from one carrier to another lose energy. This energy powers proton pumps.
Photosystems are oxidized (lose electrons), then reduced (gain electrons).
- PSII gains electrons from water splitting (photolysis).
- PSI gains electrons from PSII (via electron carriers).

Explore the intricate processes of the light-dependent reactions (Hill Reactions) in photosynthesis. This quiz covers the roles of pigments, photosystems I and II, and the movement of energized electrons. Test your knowledge on how these elements contribute to energy conversion in plants.