What distinguishes amphitrichous bacteria from monotrichous bacteria?

Amphitrichous bacteria are distinguished from monotrichous bacteria primarily by the number and arrangement of their flagella. Amphitrichous bacteria possess a flagellum at both ends of the cell, allowing for motility in multiple directions, which can be advantageous in navigating their environment. In contrast, monotrichous bacteria have a single flagellum located at one pole of the cell, providing a more limited range of movement. This distinction in flagella arrangement is key to understanding how different bacteria move and interact with their surroundings.

The other choices do not accurately reflect the differences between these types of bacteria. The cell wall structure is characterized by the presence of either peptidoglycan in Gram-positive or negative bacteria, but this feature is not directly related to the flagellar arrangement. Similarly, the shape of bacteria can vary widely among different species, regardless of their flagellar types, and color does not pertain to flagellar structure but rather to pigmentation, which is unrelated to how motility is achieved. Thus, the correct answer focuses on the flagellar arrangement, which is the defining characteristic of amphitrichous versus monotrichous bacteria.