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IB Biology HL A3.2.9 Three-domain classification Question Bank

Practise IB Biology HL A3.2.9 by interpreting rRNA evidence and comparing membrane, wall and histone differences across the three domains.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Use rRNA sequence evidence to identify the basis of three-domain classification.
  • Compare Archaea and Eubacteria using peptidoglycan, membrane lipids and histone proteins.

A3.2.9 (HL)—Three domains classification 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 A3.2.9 (HL)—Three domains classification question 1 — IB Biology HL

State the domain into which ticks are classified.

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