During photosynthesis,oxygen is evolved from........

$DCMU$ ($3$-($3$,$4$-dichlorophenyl)$-1,1-$dimethylurea) is a chemical that acts as an inhibitor of photosynthesis. What is its specific mode of action?

During non-cyclic photophosphorylation,which of the following does the electron produced through photolysis enter?

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

$ATP$ synthesis in chloroplasts and mitochondria is due to a proton gradient across the membrane. Select the correct statements with respect to $ATP$ formation in chloroplasts:
$(a)$ Protons accumulate in the lumen of the thylakoid.
$(b)$ Splitting of water occurs on the inner side of the membrane.
$(c)$ Protons accumulate on the stroma side of the chloroplast.
$(d)$ $NADP$ reductase is located on the stroma side of the membrane.

Plastocyanin contains