In Photosynthetic Cells, Synthesis of ATP by the Chemiosmotic Mechanism

Question

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during
A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.

Accepted Answer

The chemiosmotic mechanism occurs during both photosynthesis and respiration in photosynthetic cells. During photosynthesis, light energy is used to generate a proton gradient across the thylakoid membrane, which drives ATP synthesis. During respiration, the proton gradient is established by the electron transport chain, which ultimately results in ATP synthesis through the same chemiosmotic mechanism. Therefore, the synthesis of ATP by the chemiosmotic mechanism occurs during both photosynthesis and respiration.