Question

Chemiosmotic hypothesis of ATP synthesis in chloroplasts is based on

• A. Accumulation of $K^{+}$ ions
• B. Proton gradient
• C. Accumulation of Na ions
• D. Membrane potential
• E. Increase in pH of lumen

Answer 1

The correct option is B Proton gradient

The chemiosmotic hypothesis of ATP synthesis in chloroplasts is based on proton gradient. The chemiosmotic hypothesis was explained by P. Mitchell. ATP synthesis is linked to the development of a proton gradient across the membrane of the thylakoid of chloroplast and proton accumulation is towards the inside of the membrane i.e. in the lumen. Source of protons within the chloroplasts is water. The splitting of water molecule takes place on the inner side of the membrane and so the protons (hydrogen ions) are produced, they accumulate within the lumen of the thylakoids.