The gas released in photosynthesis is

Assertion $(A) : H^+$ gradient across the thylakoid membrane is essential for the formation of $\text{ATP}$.
Reason $(R) :$ Breakdown of $H^+$ gradient due to the movement of protons through $F_0$ of $\text{ATP}$ synthase releases enough energy to activate $\text{ATP}$ synthase enzyme that catalyses the formation of $\text{ATP}$.

Most herbicides attack

Which photosystem is involved in cyclic photophosphorylation?

$NADP^+$ is converted into $NADPH_2$ in

In which process is $NADP^+$ reduced to $NADPH$?