$99 \%$ of living systems are made up of four elements:

Identify the sulphur-containing vitamin.

Match the following:

$(a)$ Inhibitor of catabolic reaction	$(i)$ Ricin
$(b)$ Contains peptide bond	$(ii)$ Malonate
$(c)$ Cell wall material in fungi	$(iii)$ Chitin
$(d)$ Secondary metabolite	$(iv)$ Collagen

Select the correct option:

Assertion $A$: Water is an efficient solvent.
Reason $R$: Polar nature is an important property of water.
Which option is correct for Assertion $A$ and Reason $R$?

Refer to the given structure of adenylic acid. In this,identify $A$.

Choose the incorrect pair.