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
Biurette test is mainly done for: 
Select and explain. 
A. Carbohydrate., B. Protein., C. Lipids., D. Any of the above.
B: Protein.
Answer: B: Protein. 
Explanation: Satyanarayan – 65
When biurette is treated with dilute copper sulfate in alkaline medium, a purple color is obtained. This is the basis of biurette test widely used for identification of proteins and peptides.