Examkin

Question

Difficulty: Very hardTaxonomy and Classification

A research team isolates a novel microscopic organism from a highly acidic, boiling hot spring. Laboratory analysis confirms the organism is entirely unicellular, lacks any membrane-bound organelles, and possesses a rigid cell wall that does not contain peptidoglycan. Based on modern biological classification principles, which of the following identifies the correct Domain and Kingdom for this organism, along with the taxonomic rank that immediately subdivides that Kingdom?

  1. Domain Archaea, Kingdom Archaebacteria; immediately subdivided into PhylumAnswer
  2. B
    Domain Bacteria, Kingdom Eubacteria; immediately subdivided into Phylum
  3. C
    Domain Eukarya, Kingdom Fungi; immediately subdivided into Class
  4. D
    Domain Archaea, Kingdom Archaebacteria; immediately subdivided into Order

Answer

The organism belongs to Domain Archaea and Kingdom Archaebacteria, with the Kingdom immediately subdivided into Phylum.
The absence of membrane-bound organelles indicates a prokaryotic organism, ruling out Eukarya. The lack of peptidoglycan and the extreme environment confirm it belongs to the Domain Archaea (Kingdom Archaebacteria). In the Linnaean hierarchy, the taxonomic rank that directly follows and subdivides a Kingdom is Phylum.

Step-by-Step Solution

1
Analyze the organism's cellular structure to determine its Domain.
The organism is unicellular and lacks membrane-bound organelles.
The absence of organelles, particularly a nucleus, defines the organism as a prokaryote, eliminating Domain Eukarya.
2
Differentiate between the remaining prokaryotic domains (Bacteria vs. Archaea).
The organism lacks peptidoglycan in its cell wall and survives in extreme conditions (boiling, acidic).
Domain Bacteria (Kingdom Eubacteria) possesses peptidoglycan, whereas Domain Archaea (Kingdom Archaebacteria) does not and often includes extremophiles.
3
Determine the correct descending order of the Linnaean taxonomic hierarchy.
The rank directly below Kingdom is Phylum.
The standard sequence from broadest to most specific is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Key Concept

Taxonomic hierarchy and domain-level cellular characteristics
Estimated Time:1m 30s
Rate this question

Topics

Taxonomy and Classification

More questions from this topic