A bacterial cell exhibiting chemotaxis probably has which of the following structures?

• A. Ribosomes
• B. Plasmids
• C. Capsule
• D. Flagella

Answer: (D)

Verified step by step guidance

1. Understand the concept of chemotaxis: Chemotaxis is the movement of an organism, such as a bacterial cell, toward or away from a chemical stimulus.
2. Identify the structures involved in bacterial motility: Bacteria use specific structures to move, and the primary structure responsible for movement is the flagellum (plural: flagella).
3. Review the options given: Ribosomes are involved in protein synthesis, plasmids are extra-chromosomal DNA elements, and capsules are protective layers outside the cell wall; none of these directly enable movement.
4. Recognize that flagella are whip-like appendages that rotate to propel the bacterial cell, allowing it to move toward attractants or away from repellents, which is essential for chemotaxis.
5. Conclude that a bacterial cell exhibiting chemotaxis most likely has flagella, as these structures enable the directed movement necessary for chemotaxis.