Which is not true for arginine?

Which of the following molecules has the ability to form a zwitterion?

Amino acids containing a heterocyclic ring are:
$(i)$ Histidine
$(ii)$ Valine
$(iii)$ Arginine
$(iv)$ Proline

The list given below contains essential amino acids that are basic $(X)$ and also non-essential amino acids that are neutral $(Y)$. Identify $X$ and $Y$ from the following list:
$a)$ Lysine
$b)$ Alanine
$c)$ Serine
$d)$ Arginine
$e)$ Tyrosine

Which of the following describes the linkage of $\alpha-$amino acids in a protein molecule?

During the denaturation of proteins,which of these structures will remain intact?