During the chemiosmotic synthesis of ATP in chloroplasts, a proton gradient is developed across the thylakoid membrane. Which of the following events is directly responsible for the decrease in proton concentration in the stroma?

Step-by-step solution

The proton gradient across the thylakoid membrane is created by the accumulation of protons in the lumen and a decrease in proton concentration in the stroma. The NADP reductase enzyme is located on the stroma side of the membrane. It requires both electrons (from PS I) and protons to reduce NADP ⁺ to NADPH + H ⁺ . These protons are removed directly from the stroma, causing a decrease in the stromal proton concentration. Splitting of water adds protons to the lumen, not the stroma. Flow of protons through ATP synth