Which of the following best describes viruses?

Viruses are best described as non-cellular pathogens that contain either DNA or RNA. Unlike bacteria, fungi, or other microorganisms, viruses do not have a cellular structure. They cannot be classified as unicellular or multicellular because they lack the organizational complexity that defines cells.

Viruses consist of genetic material (either DNA or RNA) surrounded by a protein coat, sometimes with additional lipid envelopes. They cannot carry out metabolic processes independently; instead, they require a host cell to replicate and propagate. This dependence on host cells for reproduction and infectious capability is a defining characteristic of viruses.

The other options inaccurately characterize viruses. While some microorganisms have cellular structures and cell walls, viruses are fundamentally different in that they do not possess these features. Additionally, viruses do not reproduce through mitosis, nor do they have independent metabolic functions as living cells do. Understanding these unique traits is essential for recognizing the distinct nature of viruses in microbiology.