Amino acids usually exist in the form of Zwitterions which consist of:

Options

A. The basic group `-NH_2` and the acidic group `-COOH`
B. The acid group `-NH_3^+` and the basic group `CO_2^-`
C. The acid group `CO_2^+`and the acidic group `NH_3^-`
D. No acidic or basic group

Answer

B