Multiple Choice
During the light reactions of oxygenic photosynthesis, how is ATP primarily synthesized (photophosphorylation)?
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Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation
Photophosphorylation 1
Multiple Choice
In photophosphorylation during photosynthesis, what is the role of ATP synthase in the thylakoid membrane?
A
It transfers excited electrons from photosystem II to NADP+ to form NADPH.
B
It uses the proton (H+) electrochemical gradient across the thylakoid membrane to catalyze ATP formation from ADP and inorganic phosphate (Pi).
C
It fixes into carbohydrates by catalyzing the carboxylation of ribulose-1,5-bisphosphate.
D
It directly splits water to release electrons, protons, and molecular oxygen.
Verified step by step guidance1
Understand that ATP synthase is an enzyme complex embedded in the thylakoid membrane of chloroplasts, playing a crucial role in photophosphorylation during photosynthesis.
Recognize that during the light reactions, a proton (H+) gradient is established across the thylakoid membrane, with a higher concentration of protons inside the thylakoid lumen compared to the stroma.
Know that ATP synthase harnesses the energy stored in this proton electrochemical gradient by allowing protons to flow back into the stroma through its channel.
This proton flow drives the rotational mechanism of ATP synthase, which catalyzes the phosphorylation of ADP and inorganic phosphate (Pi) to form ATP.
Therefore, the primary role of ATP synthase in the thylakoid membrane is to convert the energy of the proton gradient into chemical energy stored in ATP, which is then used in the Calvin cycle and other cellular processes.
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