Which two molecules are present in saliva and function to control populations of oral bacteria?

• A. Amylase and Lipase
• B. Mucin and Lysozyme
• C. IgG and IgM
• D. Lysozyme and IgA

Answer: (D)

Saliva defends the mouth with both innate and adaptive protection at the mucosal surface. Lysozyme acts as an antimicrobial enzyme that cleaves bonds in bacterial cell walls, causing lysis and helping to keep bacterial numbers in check. Secretory IgA is the dominant antibody in saliva; it coats bacteria and toxins, prevents their adhesion to teeth and mucosa, and helps neutralize pathogens without causing inflammation. Together, these two components provide immediate enzymatic attack plus targeted mucosal immunity, effectively controlling oral bacterial populations. Other options either describe digestive enzymes (not primarily for antimicrobial action) or antibodies not primarily present in saliva (systemic IgG/IgM), or mucin alone, which is more about lubrication and barrier rather than direct antimicrobial activity.