The exoskeleton of birds and mammals is composed of which biomolecule?

The simplest amino acid is

In the given figure,what does the part labeled $M$ indicate?

What are horns,nails,and hair made of?

Given below are two statements.
Statement $I$ - Most of the blood proteins are acidic proteins.
Statement $II$ - Derived proteins are not found in nature.
In the light of above statements,select the correct option given below:

Match the following columns correctly.

Column $I$	Column $II$
$(a)$ Actin	$(i)$ Transport of respiratory gases
$(b)$ Immunoglobulin	$(ii)$ Immunity
$(c)$ Melanin	$(iii)$ Pigmentation of the body
$(d)$ Hemoglobin	$(iv)$ Muscle movement