Question

multiple choice question
the reaction center is a

chlorophyll a molecule that transfers an electron to an electron acceptor.

chlorophyll a molecule that donates an electron to water.

chlorophyll b molecule that becomes chlorophyll a when it is \excited.\

chlorophyll b molecule that captures photons of light.

Explanation:

1. Recall the concept of the reaction center in photosynthesis: The reaction center contains a special pair of chlorophyll a molecules. When light energy is absorbed, an electron from this chlorophyll a is excited and transferred to an electron acceptor, initiating the electron transport chain.
2. Analyze each option:

• Option 1: Matches the definition of the reaction center's chlorophyll a (transfers electron to acceptor).
• Option 2: Water donates electrons (to replace those lost from PSII), not the reaction center chlorophyll a donating to water. Eliminate.
• Option 3: Chlorophyll b is an accessory pigment, and it doesn't convert to chlorophyll a when excited. Eliminate.
• Option 4: Accessory pigments (like chlorophyll b) capture photons, but the reaction center's main role is electron transfer, not just photon capture. Eliminate.

Answer:

A. chlorophyll a molecule that transfers an electron to an electron acceptor.