Apentix/AP Biology/Unit 3: Cellular Energetics/Question
AP Biologymediummcq1 pt

Which statement best captures how the light-dependent reactions and the Calvin cycle depend on each other?

A.The Calvin cycle supplies ADP, phosphate, and NADP+ that the light reactions require to keep operating.
B.The Calvin cycle sends sugars back to Photosystem II to fuel further photon capture.
C.The two stages share nothing except gaseous CO2 and O2 exchanges.
D.Water produced by the Calvin cycle is split again at Photosystem II.

Explanation

Core Concept

The light reactions supply ATP and NADPH that support carbon fixation, while carbon-fixation reactions regenerate ADP, inorganic phosphate, and NADP+ that can be reused by the light reactions. If carbon fixation slows, linear electron flow can also slow as oxidized carriers become limiting. However, photosynthetic electron flow is regulated and cyclic electron flow can continue under some conditions, so it is too absolute to say photophosphorylation must simply halt.

Correct Answer

AThe Calvin cycle supplies ADP, phosphate, and NADP+ that the light reactions require to keep operating.

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