AAMC FL Practice Exam 2026 – The Comprehensive All-in-One Guide to Exam Success!

Viruses are unique entities in biology that do not fit neatly into the categories of living organisms due to their lack of cellular structure and independent metabolic activity. The statement that they contain RNA or DNA is the most accurate representation of a key characteristic of viruses. Viruses are composed of genetic material, which can be either RNA or DNA, encased in a protein coat called a capsid. This genetic material allows them to infect host cells and hijack the cellular machinery to produce more viral particles.

Regarding the other statements, viruses do not contain organelles, as they lack the complex structure of cells. They also cannot replicate independently; they require a host cell to reproduce. Lastly, viruses are not eukaryotic; they are classified separately, often as acellular or non-cellular entities, because they lack the traits that define eukaryotic organisms, such as a defined nucleus and cellular organelles. Thus, the presence of RNA or DNA is the defining characteristic that identifies viruses.