Which term describes sphere-shaped bacteria?

• A. Cocci
• B. Bacilli
• C. Cilia
• D. Bacteriology

Answer: (A)

Bacteria come in different shapes called morphologies, including spherical, rod-shaped, and spiral forms. The sphere-shaped form is called cocci. Cocci can exist alone, in pairs (diplococci), in clusters (staphylococci), or in chains (streptococci), but the common naming for sphere-shaped bacteria is cocci.

Bacilli are rod-shaped bacteria, so they describe a different shape. Cilia are hair-like projections on some cells and are not a term used to describe bacterial shapes. Bacteriology is the study of bacteria, not a shape. Therefore, the term that describes sphere-shaped bacteria is cocci.