AP BIOLOGY

Detailed explanation-1: -Viruses are small obligate intracellular parasites, which by definition contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat. Viruses may be viewed as mobile genetic elements, most probably of cellular origin and characterized by a long co-evolution of virus and host.

Detailed explanation-2: -viruses. All viruses are obligate parasites; that is, they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions.

Detailed explanation-3: -Bacteria and viruses can live outside of the human body (such as on a countertop) sometimes for many hours or days. But parasites need a living host to survive. Bacteria and parasites can often be killed with antibiotics. But these medicines can’t kill viruses.