Proteins when heated with conc. $HNO_3$ give a yellow colour. This is

Which protein is present in milk and eggs?

Assertion: $\alpha$-amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity.
Reason: $H^{+}$ ion given by carboxylic group $(-COOH)$ is captured by amino group $(-NH_2)$ having lone pair of electrons.

What is the monomer of a polypeptide?

The cell membrane is primarily composed of ...........

In which of the following is $Keratin$,a fibrous protein,absent?