Photosynthetic phosphorylation is

The electron transport chain of the photosynthetic process is:

In the chloroplast,the stroma lamellae lack the

What is present in plastocyanin?

$2 H_{2} O \rightarrow 4 H^{+} + O_{2} + 4 e^{-}$
Based on the above equation,answer the following questions:
$(a)$ Where does this reaction take place in plants?
$(b)$ What is the significance of this reaction?

The first step in photosynthesis is