Which of the following compounds will form a zwitterion?

Among the following,$L$-serine is

Consider the following statements:
Statement-$I$: The primary structure of a protein represents its amino acid sequence.
Statement-$II$: The $\alpha$-helix and $\beta$-pleated sheet structures of a protein represent its tertiary structure.

The one that does not stabilize $2^{\circ}$ and $3^{\circ}$ structures of proteins is

Which of the following contains the highest percentage of protein?

Which of the following is not an essential amino acid?