What group of organisms must rely on cellular respiration for energy?

Oxygen is required and is used to break down nutrients , like glucose sugar they ( nutrients)  are later broken down to generate ATP (energy) carbon dioxide & water . organisms can use cellular respiration including bacteria , animals, plants and fungi.

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.