[Campbell Biology P.245] Based on the text, what would most likely happen to an excited elec... | Practice Question

Based on the text, what would most likely happen to an excited electron from the special pair of chlorophyll a molecules if the primary electron acceptor were absent in its immediate environment, similar to isolated chlorophyll in a flask?

  • A: It would be transferred to another pigment molecule within the light-harvesting complex.
  • B: It would be used to synthesize ATP directly.
  • C: It would immediately drop back to its ground state, dissipating energy as light and heat.
  • D: It would transfer to the stroma to initiate the Calvin cycle.

Explanation

The text explicitly states: 'In the flask shown in Figure 10.11b, isolated chlorophyll fluoresces because there is no electron acceptor, so electrons of photoexcited chlorophyll drop right back to the ground state.' This implies that without a primary electron acceptor, the excited electron has no pathway to transfer its energy into chemical work and thus dissipates it as light fluorescence and heat.