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A3.2.2 (HL)—Difficulties with traditional hierarchy

Traditional hierarchy provides useful ranks, but extinct taxa, arbitrary rank boundaries, and convergent traits can obscure evolutionary ancestry in classification.

Syllabus
First assessment 2025
Objective
A3.2.2
Level
HL

Exam analysis

Chance of appearing1%of analysed past papers
Latest appearanceMay 2019
Most common paperPaper1
Typical marks1

Common command terms

  • Deduce

Scoring notes

Common mistake
Assuming morphological similarity always indicates close evolutionary ancestry.

Recent exam appearances

May 2019Paper1 ["HL"] · TZ228[ 1 ]A3.2.2 (HL)—Difficulties with traditional hierarchy
Practice this objective

Coverage 2019–2019 · Updated 15 Jul 2026

Concept essentials

  • Genus is narrower than family, order, and class.
  • Extinct organisms can make ancestry evidence incomplete.
  • Convergent evolution can make unrelated groups look similar.
  • Fixed taxonomic ranks do not always match evolutionary divergence.
ConceptIB Biology HL