In photosystems, the reaction center chlorophyll is the molecule that ______ when energy is transferred from antenna pigments.

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When light energy is captured by antenna pigments, it is channeled to the reaction center chlorophyll, elevating it to an excited state. In this excited state, the reaction center chlorophyll donates an electron to the primary electron acceptor. That donation leaves the reaction center chlorophyll with one fewer electron, so its oxidation state increases—it becomes oxidized. This oxidation is the first step in the electron transport that drives the photosynthetic reactions forward. The system is then reset by supplying electrons from the donor side (water splitting in PSII, or other donors in the chain) to restore the reaction center for another cycle. So the correct idea is that the reaction center chlorophyll is oxidized when energy is transferred from the antenna pigments and the electron is moved to the acceptor.