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: Microbiology
[{'content': 'Stain is not taken by capsule in gram negative organisms because the capsule consist of -a) Polysaccharidesb) Lipopolysaccharidesc) Lipidsd) Protein \nSelect and explain. \nA. b, B. c, C. ac, D. ad', 'role': 'user'}, {'content': "Answer: D \nExplanation: Capsules are protective walls that surround the cell membranes of gram-positive and gram-negative bacteria.\nThey are usually composed of simple sugar (polysaccharide) except in Bacillus anthracis it is made up of\xa0polypeptide (protein).\nCapsule is not visible in gram stained smear as it has little affinity for basic dyes.\n\nNote -\n\nFor single option go ahead for option 'a', i.e. polysaccharide because, except for Bacillus anthracis, the capsule of almost all the important bacteria is composed of sugar (polysaccharide).\nDon't get confuse with word gram-negative in question because the capsule, whether it is of grain positive or gram negative bacteria, is not visible on gram staining.", 'role': 'assistant'}]