Which structure immediately encloses the viral nucleic acid?

• A. Nucleoid
• B. Cell membrane
• C. Envelope
• D. Capsid

Answer: (D)

Verified step by step guidance

1. Understand the basic structure of a virus: Viruses are composed of genetic material (either DNA or RNA) surrounded by a protective protein coat called a capsid.
2. Identify the function of the capsid: The capsid serves to protect the viral nucleic acid from degradation and helps in the attachment and penetration of the host cell.
3. Differentiate between the capsid and other structures: The nucleoid is a region within prokaryotic cells containing genetic material, not related to viruses. The cell membrane is a structure found in cells, not viruses. The envelope is an additional layer found in some viruses, but it surrounds the capsid, not the nucleic acid directly.
4. Recognize that the capsid is the immediate enclosure: The capsid directly surrounds and encloses the viral nucleic acid, providing the first layer of protection.
5. Conclude that the capsid is the correct answer: Based on the structure and function of the capsid, it is the immediate enclosure of the viral nucleic acid.