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B4.1.3—Abiotic variables affecting distribution

Abiotic variables such as temperature, water, light, pH, salinity, nutrients and substrate conditions strongly affect species distribution patterns in ecosystems.

Syllabus
First assessment 2025
Objective
B4.1.3
Level
HL

Exam analysis

Chance of appearing3%of analysed past papers
Latest appearanceNovember 2021
Most common paperPaper3
Typical marks1–2

Common command terms

  • Outline
  • Describe
  • State
  • Suggest
  • Discuss
  • Identify
  • Distinguish

Scoring notes

Common mistake
Listing abiotic factors without giving a biological reason for their effect.

Recent exam appearances

November 2021Paper2 ["HL"] · TZ01(f)[ 2 ]B4.1.3—Abiotic variables affecting distribution
May 2018Paper3 ["HL"] · TZ216(c)(ii)[ 2 ]B4.1.3—Abiotic variables affecting distribution
May 2018Paper3 ["HL"] · TZ115(a)[ 1 ]B4.1.3—Abiotic variables affecting distribution
Practice this objective

Coverage 2018–2021 · Updated 15 Jul 2026

Concept essentials

  • Abiotic factors are non-living conditions that affect organisms.
  • Temperature, water, light, pH, salinity and minerals commonly influence distribution.
  • Transects can correlate species distribution with measured abiotic variables.
  • A factor becomes limiting when deficiency or excess restricts survival, growth or reproduction.
ConceptIB Biology HL