Final answer:
The term 'coccus' in bacterial classification denotes a spherical-shaped bacterium. This is one of three common bacterial shapes, the others being rod-shaped bacilli and spiral-shaped spirilli. The correct option is A.
Step-by-step explanation:
In the classification of bacteria based on morphology, the term 'coccus' refers to a bacterium with a spherical shape. This is one of the three basic shapes that bacteria can take, with the others being 'bacilli', which are rod-shaped, and 'spirilli', which are spiral-shaped. Cocci can be found alone or in groups, sometimes forming chains or clusters, such as staphylococci.
Bacteria are different from eukaryotic cells in that they generally lack membrane-bound organelles and have cell walls made of peptidoglycan. Yet similar to eukaryotes, they have cytoplasm, ribosomes for protein synthesis, and a plasma membrane.