Which of the following is not an amino acid?

Given below are two statements:
Statement $I:$ Amino acids have a property of ionizable nature of $-NH_2$ and $-COOH$ groups,hence have different structures at different $pH$.
Statement $II:$ Amino acids can exist as Zwitterionic form at acidic and basic $pH$.
In the light of the above statements,choose the most appropriate answer from the options given below:

Non-essential amino acids are:

Which of the following molecules acts as an electrolyte in a solution?

$P$ - Statement: Hemoglobin is a conjugated protein.
$Q$ - Statement: Hemoglobin is an essential protein for the transport of $O_2$.

Which macromolecules provide protection against infectious agents?