What are viruses primarily composed of?

• A. DNA and protein
• B. RNA and lipids
• C. Protein coat surrounding nucleic acid
• D. Cell membrane and cytoplasm

Answer: (C)

Viruses are primarily composed of a protein coat that surrounds nucleic acid, which can be either DNA or RNA. The protein coat, known as a capsid, serves to protect the viral genetic material and facilitate its entry into host cells. This structure is essential for a virus's ability to infect a host and replicate, as the capsid helps the virus attach to specific cells and delivers its genetic material into the host.

In contrast, other choices lack the essential components of a virus. While some viruses may have lipid envelopes, the fundamental structure is the protein coat with nucleic acid at its core. Additionally, bacteria or cellular life would not be relevant to viruses, as they do not possess cell membranes or cytoplasm in the same way living cells do. Hence, the composition characterized by the combination of a protein coat and nucleic acid accurately defines the structure of viruses.