Light is necessary during photosynthesis for

$PS-I$ is located on the

In the given figure,for which process is '$A$' important?

Identify the correct pathway of electron transport in the $Z$-scheme.

Which are incorrect sentences for non-cyclic photophosphorylation?
$(1)$ $Z$ shape is formed when all the carriers are placed in a sequence on a redox potential scale.
$(2)$ The $4e^-$ released are accepted by various electron acceptors and finally enter into $PS-II$ instead of returning to $PS-I$.
$(3)$ In this process both $PS-I$ and $PS-II$ take part.
$(4)$ As the electrons released in various ways do not return to their original donors,such an electron transport is called non-cyclic electron transport.

In photosystem $II$,the reaction center chlorophyll $a$ absorbs $680 \, nm$ wavelength of ...... causing electrons to become excited and jump into an orbit.