Glycine may be classed as all of the following except

Which of the following is a condensation polymer?

The correct structure of Rhumann's Purple,the compound formed in the reaction of ninhydrin with proteins is :

The condensation polymer among the following is

Which amino acid from the following contains $-CH_3$ as a side chain?

Assertion $(A)$: An optically active amino acid can exist in three forms depending on the $pH$ of the solution.
Reason $(R)$: Amino acids contain both acidic and basic groups; they exist as a zwitterion in aqueous medium,anionic form in basic medium,and cationic form in acidic medium.