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A4.2.4—Ecosystem loss causes

Ecosystem loss is driven by habitat conversion, fragmentation, climate stress, acidification, pollution, and resource extraction that reduce species survival worldwide.

Syllabus
First assessment 2025
Objective
A4.2.4
Level
HL

Exam analysis

Chance of appearing3%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper1A
Typical marks1–2

Common command terms

  • Outline
  • Explain
  • Describe
  • Suggest

Scoring notes

Common mistake
Naming deforestation without explaining loss of habitat, food, shelter or breeding sites.

Recent exam appearances

November 2025Paper1A ["HL"] · TZ334[ 1 ]A4.2.4—Ecosystem loss causes
May 2025Paper2 ["HL"] · TZ17(c)[ 2 ]A4.2.4—Ecosystem loss causes
May 2023Paper3 ["HL"] · TZ117(a)[ 1 ]A4.2.4—Ecosystem loss causes
Practice this objective

Coverage 2023–2025 · Updated 15 Jul 2026

Concept essentials

  • Deforestation reduces biodiversity by removing habitat and essential resources.
  • Fragmentation can isolate populations and increase edge effects within remaining habitat.
  • Rising sea temperatures and ocean acidification can damage coral reef ecosystems.
  • Logging and plantation agriculture are major drivers of mixed dipterocarp forest loss.
ConceptIB Biology HL