Which of the following is a basic characteristic of viruses?

• A. They can generate ATP independently using ribosomes and mitochondria.
• B. They have both DNA and RNA as genetic material in the same particle.
• C. They reproduce by binary fission.
• D. They require a living host cell to replicate.

Answer: (D)

Verified step by step guidance

1. Understand that viruses are unique infectious agents that differ fundamentally from cellular life forms such as bacteria and eukaryotic cells.
2. Recall that viruses lack the cellular machinery necessary for independent metabolism, including the inability to generate ATP or carry out protein synthesis on their own, as they do not have ribosomes or mitochondria.
3. Recognize that viruses contain either DNA or RNA as their genetic material, but never both simultaneously within the same viral particle.
4. Know that viruses do not reproduce by binary fission, which is a method of asexual reproduction typical of bacteria; instead, they replicate by hijacking the host cell's machinery.
5. Conclude that the defining characteristic of viruses is their absolute dependence on a living host cell to replicate, as they must use the host's metabolic and synthetic systems to produce new viral particles.