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
Cell wall deficient organisms are 
Select and explain. 
A. Chlamydia, B. Mycoplasma, C. Streptococcus, D. Anaerobes
B: Mycoplasma
Answer: B: Mycoplasma 
Explanation: Ans. is 'b' i.e., Mycoplasma Mycoplasma Smallest free living organism, are prokaryotes Lack cell wall, are bounded by a triple layered unit membrane that contains sterol (therefore mycoplasmas require sterol for growth). Their lack of cell wall is associated with cellular pleomorphism and resistance to cell wall - active antimicrobial agents, such as penicillins and cephalosporins (13 - lactam drugs). Multiplication is by binary fission. Unique among prokaryotes is the requirment of most mycoplasmas for cholesterol and related sterols.