In $\text{alanyl-glycyl-leucyl-alanyl-valine}$,the number of peptide linkages is $......$

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.

Among the following,$L$-serine is

In aqueous solution,amino acids exist as.......

Which of the following compounds does not exist as a zwitterion?

Which compound can exist in a dipolar (zwitter ion) state?