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IB ESS HL 3.1 Biodiversity and Evolution Question Bank

Practise IB ESS HL 3.1 by analysing diversity indices and evidence for natural selection, isolation and speciation.

Syllabus
First assessment 2026
Course
ESS HL
Level
HL

Exam points

  • Analyse habitat, species and genetic diversity using richness, evenness and abundance data.
  • Evaluate natural selection from heritable variation, selection pressure and differential reproduction.
  • Analyse speciation through isolation, divergent selection and loss of fertile reproduction.
  • Calculate and interpret Simpson’s reciprocal index, including limitations of sampling evidence.

3.1 Biodiversity and evolution question 1

[Maximum number: 1]
Global biodiversity extinction-risk categories

Figure:Global biodiversity extinction-risk categories

Changes in species extinction risk from 1980 to 2015

Figure:Changes in species extinction risk from 1980 to 2015

the two biodiversity charts shown above are based on records for species diversity. Identify one other factor that may be measured to assess the diversity of life on Earth.

3.1 Biodiversity and evolution question 2

[Maximum number: 11]

Question (a)

(a)

Outline the mechanisms by which a terrestrial species may have evolved from an aquatic ancestor.

[ 4 ]

Question (b)

(b)

Explain the ways in which species diversity and an abundance of plant and herbivore species will increase the resilience of an ecosystem.

[ 7 ]

3.1 Biodiversity and evolution question 3

[Maximum number: 7]

Explain one natural and one human-caused factor that influences changes in biodiversity.

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