Virus classification — The primary basis for separating viruses into major groups is:
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ANature of the host (bacteria, plant, or animal)
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BNucleic acid characteristics (DNA/RNA, sense, strandedness, replication strategy)
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CCapsid symmetry
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DDiameter of the virion or nucleocapsid
Answer
Correct Answer: Nucleic acid characteristics (DNA/RNA, sense, strandedness, replication strategy)
Explanation
Introduction / Context:Modern virology relies on genome type and replication strategy to classify viruses at high levels. This echoes the Baltimore classification and underpins diagnostics and antiviral development.
Given Data / Assumptions:
- Possible criteria include host range, capsid symmetry, and particle size.
- However, genome and replication mode dictate core biology.
Concept / Approach:At the broadest grouping, genome properties (DNA vs RNA; ss vs ds; positive-sense vs negative-sense; reverse-transcribing) and how genomes are expressed/replicated dominate classification because they determine essential enzymes, replication sites, and susceptibilities to drugs.
Step-by-Step Solution:
Identify primary discriminator: nucleic acid and replication strategy.Down-rank morphology/size; useful but secondary.Note that host range is informative for ecology, not for top-level taxonomy.Verification / Alternative check:Reference frameworks consistently group viruses into DNA/RNA and Baltimore classes I–VII, before fine-graining by morphology and host range.
Why Other Options Are Wrong:
- Host nature: many unrelated viruses infect the same host group.
- Capsid symmetry: shared across disparate families.
- Diameter: overlaps widely and is not diagnostic.
Common Pitfalls:Overemphasizing EM morphology; two morphologically similar viruses can have radically different replication strategies.
Final Answer:Nucleic acid characteristics (DNA/RNA, sense, strandedness, replication strategy)