Practice IB Biology Topic A3.2 Classification and Cladistics with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for A3.2 Classification and Cladistics and mirrors Paper 1A, 1B, 2 style where relevant.
Get instant solutions, detailed explanations, and build confidence with questions aligned to IB examiner expectations.
The cladogram shows some of the groups in the three domains.
What domains do X, Y and Z represent?
| Domains | |||
|---|---|---|---|
| X | Y | Z | |
| A. | prokaryote | archaea | eukaryote |
| B. | archaea | eubacteria | prokaryote |
| C. | eubacteria | archaea | eukaryote |
| D. | eubacteria | prokaryote | eukaryote |
Life is incredibly diverse, yet all organisms share common features.
Outline the characteristics used to distinguish between the three domains of life.
Describe how organisms are classified into taxa.
Explain why classification systems are constantly revised.
A newly discovered aquatic species possesses both vertebrae and lungs but LACKS the ability to see ultraviolet (UV) light and does NOT produce amniotic eggs. Based on the cladogram, which organism is it most closely related to?
The disagreement between “splitters” and “lumpers” in taxonomy shows that scientific classification is…
The figure shows a phylogenetic tree of land plants, Charophyta, and several green-algal clades (including Chlorophyta and Prasinodermophyta).
Based on the phylogenetic tree, identify two major evolutionary clades that fall under Chlorophyta.
Explain why molecular (gene or protein sequence) data is often preferred over morphological traits when building phylogenetic trees like this.
Describe two advantages of classifying organisms based on shared evolutionary ancestry (cladistics) rather than superficial similarities.
Some relationships in the phylogenetic tree are marked with dashed lines. State what these indicate about the certainty of these relationships, and explain how future data might resolve them.
Using the tree, deduce which group is more closely related to land plants: Picocystophyceae or Charophyta.