This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
True about denaturation of proteins is all except 
Select and explain. 
A. Disruption of secondary structure occurs, B. Sequence of amino acids remain the same, C. Biological activity is retained, D. Crystallization
C: Biological activity is retained
Answer: C: Biological activity is retained 
Explanation: Denaturation is always accompanied by a loss of biological function, e.g. enzymes are inactivated.
This is because biological functions of proteins depend on their higher order structures.
Denaturation disrupts higher order (secondary, tertiary and quaternary) structure, but the primary structure (amino acid sequence) remains intact.