Read the passage carefully and answer the questions.

Carbohydrates are naturally formed organic compounds from various plants. The common chemical formula, $(C_x(H_2O)_y)$ was considered as hydrates of carbon to derive the various carbohydrates. For instance, the general formula for glucose $(C_6H_{12}O_6)$ easily fits into the above formula. Carbohydrates also called saccharides are classified on the basis of their behavior towards hydrolysis. Monosaccharides cannot be hydrolyzed further to simpler units of polyhydroxy aldehyde or ketones. About 20 monosaccharides are known to occur in nature. Carbohydrates that yield large number of monosaccharide units are called polysacccharides. Amino acids contain $(-NH_2)$ and $(-COOH)$, which can be classified in various forms. Proteins are polymers of alpha amino acids which are connected to each other by a peptide bond or peptide linkage. When a native protein is subjected to physical change, its globules unfold and helix get uncoiled and the protein loses its biological activity. The protein is said to be denaturated.

During denaturation process of protein which structure(s) remain intact?

Primary structure

The correct answer is Option (2) → Primary structure **

During denaturation of proteins, the native structure unfolds due to physical or chemical changes:

• Secondary, tertiary, and quaternary structures are disrupted.
• Primary structure (the sequence of amino acids linked by peptide bonds) remains intact, because denaturation does not break covalent peptide bonds.