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Viruses are primitive biological infectious agents that live only in the cells of bacteria, plants, and animals. A specific virus invades and reproduces inside of a specific living cell until the cell explodes, spewing hundreds of copies; however, a virus cannot live outside of a cell. Viruses may be spherical, rod-shaped, or in the case of those that attack bacteria, like a screwdriver with clasps. Viruses are so tiny that they can only be seen by means of an electron microscope. Viruses are pseudo-life forms and do not match the commonly used definition of life. They do not have a cell structure, and must reproduce inside of another living cell. When expelled in search of a new host, they are inert until they can connect ...

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