Question

Which of the following best explains how the light reactions of photosynthesis generate ATP?

A. As photosystem II (PSII) absorbs energy from light, electrons are excited to a higher energy level and accepted by ADP to form ATP.
B. A proton gradient drives the formation of ATP from ADP and inorganic phosphate via ATP synthase.
C. Energy from light excites ATP synthase, causing it to bind ADP with inorganic phosphate to form ATP.
D. ADP accepts excited electrons at the end of the electron transport chain (ETC) to form ATP.

Answer 1

B. A proton gradient drives the formation of ATP from ADP and inorganic phosphate via ATP synthase.

Step-by-step explanation:

Light reaction of photosynthesis includes the splitting of water in the presence of sunlight and electron transfer from PSII to PSI via an electron transport system. During the transfer of electron through cytochrome of the electron transport system, the proton concentration gradient is generated across thylakoids. The proton concentration gradient is harvested to drive ADP phosphorylation by the catalytic site of ATP synthase accompanied by downhill movement protons through its proton channels.