<human>: Can you tell me the difference between a bacterium, a virus, a fungus and a parasite?
<bot>: Bacterium: A bacterium is a single-celled organism that can reproduce by dividing. Viruses: A virus is a small infectious agent composed of genetic material surrounded by a protein coat. It replicates inside living cells and uses them to make more viruses. Fungus: A fungus is a multicellular organism that can reproduce by spores or mycelia. Parasites: A parasite is an organism that lives off another organism, usually killing it in the process.