Question

ATP is produced when protons (H+) flow down the gradient through the H+ channel/ATP synthase in the thylakoid membrane. A researcher discovers a drug that slows down the passage of protons through the H+ channel/ATP synthase. What is expected to happen if this drug is applied to the chloroplasts?

a) The pH in the chloroplast stroma will increase, and less ATP will be produced.
b) The pH in the chloroplast stroma will decrease, and less ATP will be produced.
c) The pH in the chloroplast stroma will increase, and more ATP will be produced.
d) The pH in the chloroplast stroma will decrease, and more ATP will be produced.

Answer 1

The application of a drug that slows down proton passage through H+ channel/ATP synthase in chloroplasts would lead to an increase in pH in the stroma and a decrease in ATP production.

Step-by-step explanation:

If a drug slows down the passage of protons through the H+ channel/ATP synthase in the thylakoid membrane of chloroplasts, the consequent outcomes would be an increase in the pH in the chloroplast stroma due to the buildup of H+ in the thylakoid lumen and a decrease in the production of ATP. This is because the chemiosmotic gradient that drives the synthesis of ATP would be disrupted, reducing the flow of protons that is necessary for the ATP synthase to attach a third phosphate group to ADP, forming ATP.