What is the composition of the enzyme $ATPase$?

The first event in photosynthesis is

$ATP$ synthesis in chloroplasts and mitochondria is due to a proton gradient across the membrane. Select the correct statements with respect to $ATP$ formation in chloroplasts:
$(a)$ Protons accumulate in the lumen of the thylakoid.
$(b)$ Splitting of water occurs on the inner side of the membrane.
$(c)$ Protons accumulate on the stroma side of the chloroplast.
$(d)$ $NADP$ reductase is located on the stroma side of the membrane.

The oxygen evolved during photosynthesis comes from water molecules. Which one of the following pairs of elements is involved in this reaction?

The chemiosmotic hypothesis for $ATP$ synthesis in chloroplasts and mitochondria is based on the .......

The movement of electrons as per $Z$-scheme in light reaction is