Question

In photosynthesis, an electrochemical gradient of hydrogen ions is established by the movement of protons into the

• A. Stroma
• B. Thylakoid space
• C. Inner membrane
• D. Matrix

Answer 1

Answer: (B)

Thylakoid space

During photosynthesis an electrochemical gradient or proton motive force is created by release (photolysis) or movement of protons into thylakoid lumen from the stroma. The energy released during this movement is used for the formation of ATP molecules by ATP synthase, CF${}_o$, CF${}_1$ particles.

The thylakoid membrane is impermeable to protons, so the protons are transported through symporter proteins, H${}^{+}$/Cl${}^{-}$ or by antiporter protein,$\uparrow$H${}^{+}$/$\downarrow$Mg${}^{+2}$

So, the correct answer is 'Thylakoid space'.