This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
Gram-negative bacteria doesn't take gram stain because it is made of 
Select and explain. 
A. Polysaccharide, B. Lipopolysaccharide, C. Techoic acid, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: The exact mechanism of gram reaction is not known. The possible reason is: Gram-positive bacteria have a more acidic protoplasm, which accounts for their retaining the basic primary dye more strongly. Dye iodine complex is retained in gram-positive cells by thick peptide glycan mesh and is readily wash through the very thin peptidoglycan layer of gram-negative cells. Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 13