A bacterial cell exhibiting chemotaxis must have which of the following structures?

• A. Capsule
• B. Flagella
• C. Fimbriae
• D. Pili

Answer: (B)

Verified step by step guidance

1. Understand the concept of chemotaxis: Chemotaxis is the movement of an organism in response to a chemical stimulus, typically moving toward nutrients or away from harmful substances.
2. Identify the structures involved in bacterial motility: Among the options, flagella, fimbriae, pili, and capsule, only some are related to movement.
3. Recall the function of each structure: Flagella are whip-like appendages that enable bacterial movement; fimbriae and pili are primarily involved in attachment and conjugation; capsules protect the cell but do not aid in movement.
4. Connect chemotaxis to the structure responsible for movement: Since chemotaxis requires movement toward or away from chemicals, the structure enabling this motility is the flagella.
5. Conclude that a bacterial cell exhibiting chemotaxis must have flagella to move effectively in response to chemical signals.