Which term describes an extremely small particle consisting of an outer shell and genetic material?

Which term describes an extremely small particle consisting of an outer shell and genetic material?

• A. Virus
• B. Bacteria
• C. Immune system
• D. Vaccine

Answer: (A)

Viruses are extremely small particles that have a protective outer shell called a capsid and genetic material (DNA or RNA) inside. Some also have a lipid envelope around the shell. They aren’t cells and can’t carry out metabolism or reproduce on their own; they need to invade a host cell to replicate. This combination of a shell around genetic material and dependence on a host to multiply is what defines a virus. Bacteria are living cells with their own metabolic systems, so they don’t fit the description of a tiny particle with just a shell and genetic material. The immune system isn’t a particle at all but the body’s defenses, and a vaccine is a preparation used to train the immune system, not a small particle containing genetic material.

Viruses are extremely small particles that have a protective outer shell called a capsid and genetic material (DNA or RNA) inside. Some also have a lipid envelope around the shell. They aren’t cells and can’t carry out metabolism or reproduce on their own; they need to invade a host cell to replicate. This combination of a shell around genetic material and dependence on a host to multiply is what defines a virus.

Bacteria are living cells with their own metabolic systems, so they don’t fit the description of a tiny particle with just a shell and genetic material. The immune system isn’t a particle at all but the body’s defenses, and a vaccine is a preparation used to train the immune system, not a small particle containing genetic material.