Which among the following compounds contains both,amino and carboxyl groups in it?

The $N$ atom which does not contribute to the basicity of the given compound is:

For an amino acid,the ionization constant for the carboxyl group is $pK_{a_1} = 2.34$ and for the ammonium ion is $pK_{a_2} = 9.6$. At what $pH$ will the isoelectric point of the amino acid be?

Which structure of protein remains intact after coagulation of egg white on boiling?

The test used for identifying peptide linkage in proteins is

Thyroxine produced in the thyroid gland is an iodinated derivative of