Which of the following amino acids contains a heterocyclic ring in its side chain $(R)$ group?

Which of the following structures of proteins represents its constitution?

$A$ nanopeptide contains $\dots$ peptide linkages.

The number of possible tripeptides formed involving alanine $(ala)$,glycine $(gly)$,and valine $(val)$,where no amino acid has been used more than once is:

Which of the following amino acids possesses two chiral centres?

Which gas is found in the form of proteins in plants and animals?