A3.1 Diversity of organisms

Diversity of organisms links variation, species concepts, classification tools, chromosome evidence, and genome comparisons to explain biological similarity and difference.

What you’ll learn

15 learning objectives

Choose one objective for a focused lesson, or study the complete topic.

Exam analysis

An aggregate view of how the complete A3.1 Diversity of organisms appears across past papers.

Chance of appearing32%of analysed past papers

Latest appearanceNovember 2025

Most common paperPaper1

Most tested objectives

A3.1.7—Karyotyping and karyograms10 questions
A3.1.2—Species as groups with shared traits8 questions
A3.1.8—Unity and diversity of genomes within species7 questions

Common question formats

Data analysis
Definition or recall
Process explanation
Structured response
Diagram interpretation
Calculation
Comparison
Evaluation
Graph interpretation
Case study
Essay response
Extended response
Experimental design

Exam question appearances

November 2025Paper2 ["HL"] · TZ37(c)[ 1 ]A3.1.12 (HL)—Difficulties with biological species concept

November 2025Paper2 ["HL"] · TZ17(c)[ 4 ]A3.1.13 (HL)—Chromosome number as shared trait

November 2025Paper1A ["HL"] · TZ322[ 1 ]A3.1.8—Unity and diversity of genomes within species

May 2025Paper1A ["HL"] · TZ322[ 1 ]A3.1.15 (HL)—Environmental DNA barcodes

May 2025Paper1A ["HL"] · TZ122[ 1 ]A3.1.7—Karyotyping and karyograms

Practice this topic

7 original exam-style questions based on the patterns above.

Coverage 2012–2025 · Updated 15 Jul 2026