Which fluid contains lysozyme with antibacterial properties?

• A. Aqueous humor
• B. Tears
• C. Synovial fluid
• D. Blood plasma

Answer: (B)

Lysozyme is an antibacterial enzyme that attacks bacterial cell walls by breaking down peptidoglycan, a key component of many bacteria. It is a common part of mucosal secretions and provides immediate, nonspecific defense. Tears contain a relatively high amount of lysozyme, which helps protect the surface of the eye from invading bacteria as tears wash over and lubricate the eye. That’s why this fluid has antibacterial properties. The other fluids listed aren’t known for containing lysozyme in meaningful amounts under normal conditions, so they don’t contribute the same lysozyme-mediated antibacterial action as tears do.