In oxygenic photosynthesis, the primary role of chlorophyll pigments is to:

• A. Serve as the terminal electron acceptor in the photosynthetic electron transport chain
• B. Absorb photons and convert light energy into excited electrons that drive the light reactions
• C. Fix ${\mathrm{CO}}_2$ into carbohydrates during the Calvin cycle
• D. Split $H_{2}O$ directly to release $O_2$ without involvement of a protein complex

Answer: (B)

Verified step by step guidance

1. Understand the role of chlorophyll pigments in oxygenic photosynthesis, which primarily involves capturing light energy.
2. Recognize that chlorophyll absorbs photons (light energy) and converts this energy into excited electrons, initiating the light-dependent reactions.
3. Note that chlorophyll is not the terminal electron acceptor; instead, it donates excited electrons to the electron transport chain.
4. Distinguish that the fixation of CO2 into carbohydrates occurs later in the Calvin cycle, not directly by chlorophyll pigments.
5. Acknowledge that the splitting of H2O to release O2 is catalyzed by a protein complex called the oxygen-evolving complex, not directly by chlorophyll.