This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Innate immunity is stimulated by which part of bacteria? 
Select and explain. 
A. Carbohydrate sequence in cell wall, B. Flagella, C. Bacterial cell membrane, D. Nucleus
A: Carbohydrate sequence in cell wall
Answer: A: Carbohydrate sequence in cell wall 
Explanation: ANSWER: (A) Carbohydrate sequence in cell wallREF: Ganong's physiology 23rd edition page 69, htty://www. ncbi.nlm.nih.gov/pubmed/11581570Innate immunity does not have the specificity of adaptive immunity, but is capable of distinguishing self from nonselfBacterial lipopolysaccharides (LPS) are the major outer surface membrane components present in almost all Gram-negative bacteria and act as extremely strong stimulators of innate or natural immunity in diverse eukaryotic species ranging from insects to humans.LPS consist of a poly- or oligosaccharide region that is anchored in the outer bacterial membrane by a specific carbohydrate lipid moiety termed lipid A. The lipid A component is the primary immunostimulatory centre of LPS.