Biologists believe that in the earliest version of photosynthesis,the energized photosystem electron simply cycled back to the chlorophyll molecule.Which of the following limitations would NOT be imposed by such a system? A) No molecular oxygen would be generated. B) No electrons would be available to reduce the carbon in CO₂. C) Cells could produce ATP but not sugars. D) Cells could produce O₂ but not sugars.

Question

Quizplus · Accepted Answer

In the earliest version of photosynthesis where the electron simply cycled back to the chlorophyll molecule, the system would not be able to split water molecules to generate molecular oxygen. This means that molecular oxygen (O2) would not be produced, making choices A, B, and C relevant limitations. However, the statement in choice D is incorrect because it suggests that cells could produce something (represented by the placeholder O₂) but not sugars. Since the cycling electron system is primarily limited in its ability to produce NADPH and thus sugars, but not directly related to producing other molecules like oxygen, choice D does not represent a limitation of such a system.

Biologists Believe That in the Earliest Version of Photosynthesis,the Energized