What is the advantage of light reactions producing $ATP$ and $NADPH$ on the stromal side of the thylakoid membrane?

In photosynthesis,light energy is utilized in:

In plants,the Hill reaction is observed during .........

Which of the following elements is essential for the photolysis of water?

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 $\text{ATP}$.

In which direction does the proton gradient develop in the chloroplast?