Diplococci refer to bacteria that occur in what arrangement?

• A. Pairs
• B. Clusters
• C. Chains
• D. Singles

Answer: (A)

Diplococci describe bacteria that appear as paired spheres. The prefix diplo- means double or in pairs, and cocci are round bacteria, so when these cells divide they stay attached in pairs rather than spreading out. That’s why you’d observe two spheres together under the microscope.

This contrasts with other arrangements: chains occur when cocci divide in a line, forming a string of cells, while clusters form grape-like groups from multiple cells sticking together. Some cocci can also appear as singles if they don’t remain attached after division. Classic examples of diplococci include Neisseria species and Streptococcus pneumoniae, which helps differentiate this arrangement from the others.