Antibodies are macromolecules of which of the following?

Which factor causes the denaturation of proteins?

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:

$A$ - In the solution of different $pH$,the structure of amino acids changes.
$R$ - It is because of the ionisable nature of $-NH_2$ and $-COOH$ groups.

Hemoglobin consists of two alpha and two beta chains. How many heme groups are present in the structure of hemoglobin?

What is the end of a polypeptide chain that contains a free amino group called?