Which of the following is a primary function of a bacterium's capsule?

• A. Protection against phagocytosis
• B. Synthesis of ATP
• C. Protein synthesis
• D. Motility through flagella

Answer: (A)

Verified step by step guidance

1. Understand that a bacterial capsule is a gelatinous outer layer surrounding the cell wall of some bacteria.
2. Recall the main functions of bacterial capsules, which include protection from environmental threats and helping bacteria evade the host immune system.
3. Recognize that protection against phagocytosis means the capsule helps bacteria avoid being engulfed and destroyed by immune cells like macrophages.
4. Eliminate options that are not related to the capsule's function: synthesis of ATP (energy production) and protein synthesis occur inside the cell, not in the capsule.
5. Note that motility through flagella is a function of flagella, not the capsule, so the primary function of the capsule is protection against phagocytosis.