Water splitting complex is physically located:

Proton gradient is very important across the membrane because

In photosystem-$I$,the first electron acceptor is

The chemiosmotic mechanism of $ATP$ synthesis was proposed by:

Read the following four statements,$(i), (ii), (iii)$ and $(iv)$ and select the right option having both correct statements.
Statements:
$(i)$ $Z$ scheme of light reaction takes place in the presence of $PSI$ only.
$(ii)$ Only $PSI$ is functional in cyclic photophosphorylation.
$(iii)$ Cyclic photophosphorylation results in the synthesis of $ATP$ and $NADPH_2$.
$(iv)$ Stroma lamellae lack $PSII$ as well as $NADP$ reductase.

$ATPase$ enzyme consists of two parts. What are those parts? How are they arranged in the thylakoid membrane? Conformational change occurs in which part of the enzyme?