Which element is required for the activity of carbonic anhydrase?

Assertion $A$: Phosphorus is essential in the structure of $ATP$.
Reason $R$: Magnesium is essential in the synthesis of $ATP$.
Which option is correct for Assertion $A$ and Reason $R$?

What is the effect of sulphur on root development in plants?

Select the correct match.

Match the following:

Column-$I$	Column-$II$
$(1)$ Nitrogen	$(p)$ Formation of mitotic spindle
$(2)$ Phosphorus	$(q)$ Protein,vitamins
$(3)$ Potassium	$(r)$ Phosphorylation reactions
$(4)$ Calcium	$(s)$ Maintain the turgidity of cells

Which mineral element is essential for the structure of nucleic acids and cell membranes?