Which statement regarding viruses is incorrect?

The statement that viruses cannot survive in the environment for any length of time outside of a human's or animal's body is incorrect because many viruses have demonstrated the ability to persist in the environment under certain conditions. Some viruses can remain viable on surfaces and in aquatic environments for extended periods, which can facilitate their transmission. For instance, viruses like norovirus, which is responsible for gastroenteritis outbreaks, can survive on surfaces for days or even weeks. Environmental stability is crucial for their spread, as they may infect hosts upon contact after surviving outside living organisms.

The other statements accurately reflect the nature of viruses. They have no independent metabolism and rely entirely on host cells for replication. Their size, usually between 10 to 25 nm, is indeed below the resolution limit of optical microscopes, requiring electronic microscopy for visualization. Lastly, certain viruses are known to cause significant public health issues, including acute epidemics of gastroenteritis, illustrating their ability to impact large populations.