Final answer:
One-celled microorganisms known for being either harmful or nonharmful are called bacteria, which are prokaryotic and can independently replicate. Bacteria can act as pathogens but they differ from viruses, as they are alive independently of a host cell and can be treated with antibiotics, while viruses require antiviral drugs.
Step-by-step explanation:
One-celled microorganisms that are either disease-producing or nondisease-producing are called bacteria. Bacteria are a broad category of prokaryotic organisms that lack a membrane-bound nucleus. Unlike viruses, which are acellular and require a host to reproduce, bacteria are self-sufficient living organisms that can replicate on their own. Bacteria can be found in various environments and can be involved in numerous roles, including being pathogens. Pathogens are microorganisms that cause diseases. While some bacteria are harmful and cause diseases, many others are beneficial and play crucial roles in processes like digestion and the nitrogen cycle.
It's important to note that while bacteria and viruses can both be pathogens and cause diseases, they differ fundamentally. Viruses, like the Herpes simplex virus or those causing colds and the flu, are not considered living organisms by all scientists because they cannot reproduce without a host cell. Antibiotics are effective against bacteria but not against viruses, however, antiviral drugs can treat many diseases caused by viruses.