Final answer:
Viruses are not considered living because they lack most of the defining traits of living organisms. They cannot replicate on their own and rely on a host cell to make copies of themselves. However, they share two important traits with living organisms: genetic material and the ability to evolve.
Step-by-step explanation:
Viruses are not considered living because they do not possess most of the defining traits of living organisms. While viruses contain genetic material (DNA or RNA), they lack other components shared by all cells, such as a plasma membrane, cytoplasm, and ribosomes. Viruses cannot replicate on their own and instead rely on a host cell to synthesize their proteins and make copies of themselves. Although viruses are not living things, they share two important traits with living organisms: genetic material and the ability to evolve.