Which external structure of microorganisms directly impacts the effectiveness of the host immune system?

• A. Flagellum
• B. Capsule
• C. Nucleoid
• D. Ribosome

Answer: (B)

Verified step by step guidance

1. Identify the external structures listed in the problem: Flagellum, Capsule, Nucleoid, and Ribosome.
2. Understand the role of each structure: Flagellum is involved in motility, Nucleoid contains genetic material, Ribosome is responsible for protein synthesis, and Capsule is an outer protective layer.
3. Recognize that the host immune system interacts primarily with structures exposed on the microorganism's surface.
4. Recall that the Capsule is a polysaccharide layer that surrounds some bacteria and helps protect them from phagocytosis and other immune responses.
5. Conclude that the Capsule directly impacts the effectiveness of the host immune system by helping the microorganism evade immune detection and destruction.