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

Hormones thyroxin,adrenaline and the pigment melanin are formed from

What is a protein formed by different amino acids called?

The smallest structural units of proteins are called

Which of the following statements correctly describe the functions of proteins?
$(I)$ As an enzyme
$(II)$ As a hormone
$(III)$ Fight against infectious organisms
$(IV)$ Formation of genetic material

Polypeptide chains present in insulin are linked together by...