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A2.3.2 (HL)—Diversity of virus structure

Virus structures vary in genome chemistry and arrangement, capsid geometry, envelope presence, size, shape, and specialized components suited to different replication strategies.

Syllabus
First assessment 2025
Objective
A2.3.2
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper2
Typical marks2–7

Common command terms

  • Outline
  • State
  • Describe

Scoring notes

Common mistake
Claiming that a virus contains both DNA and RNA instead of one type of nucleic acid genome.

Recent exam appearances

November 2025Paper2 ["HL"] · TZ17(b)[ 7 ]A2.3.2 (HL)—Diversity of virus structure
May 2013Paper3 ["HL"] · TZ28(a)[ 2 ]A2.3.2 (HL)—Diversity of virus structure
Practice this objective

Coverage 2013–2025 · Updated 15 Jul 2026

Concept essentials

  • Viral genomes may be DNA or RNA and may be single- or double-stranded.
  • Viral nucleic acid can be linear, circular, or segmented among multiple molecules.
  • Capsid shapes include helical, polyhedral, conical, and complex forms.
  • Only some viruses possess a host-derived lipid envelope.
  • Named examples reveal combinations of features that cannot be inferred from one trait alone.
ConceptIB Biology HL