Are viruses alive? this a question debated among scientists throughout the world. scientists discovered the tiny, disease-causing agents that were believed responsible for such diseases as rabies and hoof-and-mouth disease. initially, scientists classified viruses as “living”, but in 1935, they began to change their thinking. scientists crystalized the tobacco mosaic virus, noting that it did not have cell structure, of even the simplest kind. there was no membrane, no nucleus, and no ribosomes. they determined that a virus was nothing more than a strand of nucleic acid, dna or rna, protected by a protein shell. scientists also believed that viruses lacked the mechanisms necessary for metabolic function. some scientists argued that viruses are capable of response to stimuli. when not in a favorable environment within a host cell, the virus remains an unchanging, dormant, organic particle. but once in contact with the susceptible host or in a favorable environment, the virus becomes active, injecting its nucleic acid into the host cell, and eventually self-replicating. in this manner, one virus is capable of producing many other viruses, identical to the original, to attack host cells. you are debating whether or not viruses are alive. you are arguing for the negative, that is, viruses are not alive. first, list the characteristics of life. then, use evidence from the passage to support your side of the debate.