Question

What structural feature distinguishes glycine from other natural $\alpha$-amino acids?

• A. It is optically inactive.
• B. It contains aromatic group.
• C. It is a dicarboxylic acid.
• D. It has a secondary amine.

Answer 1

The correct option is A It is optically inactive.

Glycine is optically inactive whereas other $\alpha$-amino acids are optically active.
Glycine is $N{H}_2-C{H}_2-COOH$. It lacks a chiral carbon atom because of two same groups $\left(H\right)$.
other natural $\alpha$-amino acids have general formula $N{H}_2-C^{\ast }HR-COOH$ and have a chiral carbon (marked with asterisk). Thus they are optically active.
Hence, (a) is correct.