Question

viruses can have either RNA or DNA but never both, but them how is it that animal viruses contain double or single stranded RNA "and" double stranded DNA?? isn't it contradicting

Answer 1

Viruses contain genetic material, that could be either RNA or DNA. No virus contains both RNA and DNA. In general, viruses that infect plants have single stranded RNA and viruses that infect animals have either single or double stranded RNA or double stranded DNA. Bacterial viruses or bacteriophages (viruses that infect the bacteria) are usually double stranded DNA viruses.