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IB Biology HL A3.2.9 Hl Three Domains Classification Questions

Use rRNA and cellular evidence to distinguish Archaea, Eubacteria and Eukarya and justify an organism’s domain classification.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Use ribosomal RNA and other molecular evidence to explain why living organisms are classified into Archaea, Eubacteria and Eukarya.
  • Distinguish Archaea, Eubacteria and Eukarya using ribosomes, histones, introns, membrane lipids and cell-wall features.
  • Identify an organism’s domain from structural, molecular or cellular evidence and justify the classification.

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Study A3.2.9 (HL)—Three domains classification conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL A3.2.9 Hl Three Domains Classification Questions question 1

[Maximum number: 1]

The black-legged tick (lxodes scapularis) is an arthropod which sucks blood from humans and other mammals. It is encountered mainly in wooded and semi-wooded areas.

Some ticks can be infected by the bacterium Borrelia burgdorferi. When a tick bites a human, the bacterium is often introduced, causing Lyme disease. Lyme disease is a public health problem in North America and, if left untreated, can cause important neurological impairment. The diagram represents the two-year life cycle of a tick.

Figure for Question IB Biology HL A3.2.9 Hl Three Domains Classification Questions question 1 — IB Biology HL

State the domain into which ticks are classified.

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