A coccus is shaped as
A a donut
B a sphere
C a filament
D a rod
The correct answer and explanation is:
The correct answer is B: a sphere.
A coccus is a type of bacterium characterized by its spherical shape. The term “coccus” comes from the Greek word “kokkos,” meaning “berry,” which describes the round shape of these bacteria. Cocci bacteria can occur singly or in various arrangements, including pairs (diplococci), chains (streptococci), clusters (staphylococci), or tetrads. The spherical form is a result of the way the cell wall forms around the bacteria as they divide.
The coccus shape allows for an efficient surface area-to-volume ratio, aiding in the exchange of nutrients and waste products. While bacteria of different shapes, such as rods (bacilli) and spirals (spirilla), also exist, cocci are specifically recognized for their rounded appearance. This shape helps with motility and attachment to surfaces in some cases, although many cocci are non-motile.
Understanding the shape of bacteria is important in microbiology because it plays a role in the identification and classification of microorganisms. The shape and arrangement of bacteria are typically observed under a microscope and are part of the diagnostic process in identifying infections or diseases. For example, Streptococcus pyogenes, a pathogen that causes strep throat, is a coccus bacterium that forms chains.
In summary, a coccus is always spherical in shape, which distinguishes it from other bacterial forms, like the filamentous structure of actinobacteria or the rod shape of bacilli.