Clusters of chlorophyll and proteins surrounded by accessory pigments that absorb sunlight and generate high-energy electrons are called?

• A. Photosystems
• B. ATP Synthase
• C. Electron Transport Chain
• D. Calvin Cycle

Answer: (A)

Photosystems are the light-harvesting clusters of chlorophyll and proteins with accessory pigments. When they absorb photons, the energy excites chlorophyll in the reaction center, transferring high-energy electrons to a primary electron acceptor and kick-starting the photosynthetic electron transport chain. This happens in the thylakoid membranes and is essential for powering the production of ATP and NADPH used in later steps of photosynthesis.

The other options don’t fit because ATP synthase uses the proton gradient to make ATP after light-driven processes have created it, not to absorb light themselves; the electron transport chain refers to the series of carriers that electrons move through after they’ve been excited, not the light-harvesting clusters; and the Calvin Cycle is the set of reactions that fixes CO2 to sugars in the stroma, using ATP and NADPH from the light reactions rather than absorbing light.