Texas A&M University (TAMU) BIOL206 Introductory Microbiology Lab Practice Exam 1

"Sarcina" refers specifically to a type of bacterial arrangement characterized by cocci that form cube-shaped structures. This arrangement occurs when cocci divide in three planes and remain attached after division, leading to a distinctive cube-like formation made up of 8 or more cells. This morphological characteristic is significant in microbiology as it can help in identifying particular bacterial species.

The arrangement is notable for its regularity and is different from the other options, which describe different cellular configurations. For instance, cocci in clusters imply a random or irregular group, while cocci in pairs indicate a simpler two-cell arrangement. Bacilli in chains describe a completely different shape and arrangement involving rod-shaped bacteria, further differentiating them from the cube-like structure of sarcina. Therefore, the correct designation of "sarcina" specifically indicates cocci arranged in a cube configuration.