A virus is best described as a cell at the boundary between living and nonliving things. This is because viruses exhibit characteristics of both living and nonliving entities. They can replicate and evolve, which are traits of living organisms, but they cannot carry out metabolic processes on their own and require a host cell to reproduce, which are traits of nonliving entities.
Here are the options and why they are or aren’t correct:
- a) One of the smallest known bacteria – Incorrect. Viruses are not bacteria. They are much smaller than bacteria and have a different structure.
- b) A cell at the boundary between living and nonliving things – Correct. This statement accurately describes the unique nature of viruses.
- c) A noncellular living organism – Incorrect. Viruses are not considered fully living organisms because they cannot carry out life processes independently.
- d) A member of the kingdom Virusae – Incorrect. There is no such kingdom as Virusae. Viruses are not classified within the traditional biological kingdoms.
- e) A chemical compound – Incorrect. Viruses are not simple chemical compounds. They are complex structures made up of proteins and genetic material.