During photosynthesis, the energy from sunlight is used to split water molecules. What happens to the hydrogen ions that are split from the water molecules?

Question

During photosynthesis, the energy from sunlight is used to split water molecules. What happens to the hydrogen ions that are split from the water molecules?

They flow out of the thylakoid, providing energy to add a phosphate group to ADP.
They build up in the thylakoid, providing energy to break apart ATP molecules.
They build up in the thylakoid, where they bond to each other to create ATP.
They flow out of the thylakoid, where they stimulate enzymes to break apart ATP.

Answer 1

They flow out of the thylakoid, providing energy to add a phosphate group to ADP.

Answer 2

During photosynthesis, the hydrogen ions (H+) that are split from the water molecules build up in the thylakoid. This buildup of hydrogen ions creates a concentration gradient that provides energy to break apart ATP molecules and convert them into ADP (adenosine diphosphate) and phosphate (Pi).