Compounds containing both amino and $-COOH$ groups are known as

What is the functional group present in serine,an amino acid,in addition to $-NH_2$ and $-COOH$ groups?

Lysine is least soluble in water in the $pH$ range:

Which protein maintains the blood sugar level in the human body?

Insulin 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.