Why Glycine exist as $(H_3N+CH_2COO^−)$ while antranilic acid ($p − NH_2 − C_6H_4 − COOH)$ does not exist as dipolar ion ?
$\begin{array}{1 1}(a)\;-COOH\text{ is too weakly acidic to transfer }H^+\text{ to the weakly basic } −NH_2\text{ attached to the electron withdrawing benzene ring}\\(b)\;-COOH\text{ is too strong acidic to transfer }H^+\text{ to the weakly basic } −NH_2\text{ attached to the electron withdrawing benzene ring}\\(c)\;-COOH\text{ is too weakly acidic to transfer }H^+\text{ to the strong basic } −NH_2\text{ attached to the electron withdrawing benzene ring}\\(d)\;-COOH\text{ is too weakly acidic to transfer }H^+\text{ to the weakly basic } −NH_2\text{ attached to the electron donating benzene ring}\end{array}$