Final answer:
RNA viruses replicate their genomes in the host cell using their own enzymes that can replicate RNA into RNA or, in the case of retroviruses, into DNA. Mutations in RNA viruses occur more frequently than in DNA viruses, leading to more rapid evolution and adaptation. Examples of human diseases caused by RNA viruses include influenza, hepatitis C, measles, and rabies.
Step-by-step explanation:
RNA viruses contain only RNA as their genetic material. To replicate their genomes in the host cell, the RNA viruses must encode their own enzymes that can replicate RNA into RNA or, in the retroviruses, into DNA. These RNA polymerase enzymes are more likely to make copying errors than DNA polymerases, and therefore often make mistakes during transcription. For this reason, mutations in RNA viruses occur more frequently than in DNA viruses. This causes them to change and adapt more rapidly to their host. Human diseases caused by RNA viruses include influenza, hepatitis C, measles, and rabies. The HIV virus, which is sexually transmitted, is an RNA retrovirus.