Which of the following could NOT be a virus based on the basic structural requirements of viruses?

• A. A particle composed of a lipid membrane with glycoproteins but no nucleic acid
• B. A particle composed of nucleic acid enclosed in a protein capsid and surrounded by a lipid envelope
• C. A particle composed only of protein and DNA (no lipid envelope)
• D. A particle composed only of protein and RNA (no lipid envelope)

Answer: (A)

Verified step by step guidance

1. Recall the basic structural requirements of a virus: it must have nucleic acid (either DNA or RNA) enclosed within a protein coat called a capsid. Some viruses also have a lipid envelope with glycoproteins, but the presence of nucleic acid is essential.
2. Analyze each option to check if it contains nucleic acid (DNA or RNA) and a protein capsid:
3. Option 1: A particle composed of a lipid membrane with glycoproteins but no nucleic acid. This lacks nucleic acid, which is essential for viral replication, so it cannot be a virus.
4. Option 2: A particle composed of nucleic acid enclosed in a protein capsid and surrounded by a lipid envelope. This fits the classic virus structure, so it could be a virus.
5. Option 3 and 4: Particles composed of protein and nucleic acid (DNA or RNA) without a lipid envelope. Since nucleic acid and protein capsid are present, these could be viruses even without a lipid envelope.