Three-domain system (Bacteria, Archaea, Eukarya): on what primary evidence is this classification based?

Introduction / Context:
Woese and colleagues proposed the three-domain system using molecular phylogenetics, revolutionizing our view of life's deepest branches. Understanding the evidence base is a common test point.

Given Data / Assumptions:

• Molecular comparisons can reveal deep evolutionary relationships better than morphology alone.
• Highly conserved genes (e.g., rRNA) are particularly informative.
• We must select the primary basis for the three-domain classification.

Concept / Approach:
The three domains—Bacteria, Archaea, and Eukarya—were delineated using comparative analyses of small-subunit ribosomal RNA sequences and later corroborated by broader genome data. Morphology, metabolism, and cell wall types vary widely and can be convergent or plastic.

Step-by-Step Solution:

Verification / Alternative check:
Subsequent whole-genome phylogenies support the tripartite division and archaeal sisterhood to eukaryotes in core information systems.

Why Other Options Are Wrong:
B/C/D: Useful for ecology and diagnostics but insufficient to resolve domains across deep time.

Common Pitfalls:
Overemphasizing single phenotypic traits that can evolve repeatedly; molecular data provide a more robust phylogenetic signal.

Final Answer:
nucleic acid sequence data