Question

why do hydrogen ions flow from the thylakoid space to the stroma through atp synthase? a. they are pumped actively through atp synthase. this uses up atp energy and causes the production of adp and phosphate. b. they flow passively from high to low concentration via facilitated diffusion. as they flow through atp synthase, the enzyme spins and produces atp. c. they flow through the calvin cycle and produce light. d. hydrogen ions do not actually flow from the thylakoid space to the stroma. they flow the opposite way.

Explanation:

During photosynthesis, a proton - gradient is established in the thylakoid space. Hydrogen ions flow passively from an area of high concentration (thylakoid space) to an area of low concentration (stroma) through ATP synthase via facilitated diffusion. As they pass through, the enzyme ATP synthase spins and uses the energy to produce ATP from ADP and phosphate. Option A is incorrect as it's not an active - pumping process using ATP energy in this step. Option C is wrong because hydrogen ions do not produce light in the Calvin cycle. Option D is incorrect as hydrogen ions do flow from the thylakoid space to the stroma.

Answer:

B. They flow passively from high to low concentration via facilitated diffusion. As they flow through ATP synthase, the enzyme spins and produces ATP.