Question

Primary structure of proteins is due to the presence of
A) Peptide bonds
B) Disulphide (S-S) linkages
C) Hydrogen bonds
D) Ionic bonds

Answer 1

As we know that in chemistry, chemical bonds are three types of classification. This classification is based on electron binding in the bond. There are covalent bonds, ionic bonds and coordinate bonds. The covalent bond is nothing but the mutually sharing of electrons between the two atoms in the molecule. The ionic bond is nothing but highly electronegativity pulls the electrons towards itself, least electronegativity atoms lose the electrons in the molecule. The coordinate bond is nothing but the pair of the electrons from one atom to another atom in the molecule. It is mainly seen in coordination chemistry.
Some more special bonds are also in the chemical sciences like dipole-dipole interaction, Van Der Waals force, Peptide bonds and hydrogen bonds.

Complete answer:
We need to know that protein is one of the main sources of the body. It is made up of amino acids. The amino acids are nothing but the bond between the amines and carboxylic acids by using peptide bonds in the amino acids and form the structure of the proteins.
The protein is composed mainly of four atoms. There are carbon, nitrogen, hydrogen and oxygen atoms.
The structure of proteins can be classified by three types. These classification of proteins is based on the length of the molecules. There are primary structures of proteins, secondary structure of proteins and tertiary structure of proteins. Primary structure of proteins is due to the presence of peptide bonds.
According to the above discussion, we conclude the primary structure of proteins is due to the presence of peptide bonds.

Hence, option A is the correct answer.

Note:
We represent the arrows by using the dipole-dipole interaction direction in the molecule. The electronegativity difference in the bonded atom plays a vital role whether the bond is ionic or covalent or polar covalent bond. The electronegativity difference between the bonded atom is lesser than $1.7$, which means it is considered a covalent bond. If the electronegativity difference between the bonded atom is equal to $1.7$, it is considered a polar covalent bond. If the electronegativity difference between the bonded atom is greater than $1.7$, it is considered a polar bond.