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B4.2.6—Saprotrophic nutrition

Saprotrophs externally digest dead organic matter by secreting enzymes and absorbing soluble products, recycling nutrients through decomposition processes in ecosystems.

Syllabus
First assessment 2025
Objective
B4.2.6
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper1
Typical marks1

Common command terms

  • Identify

Scoring notes

Common mistake
Confusing saprotrophs with detritivores that ingest dead material.

Recent exam appearances

May 2023Paper1 ["HL"] · TZ114[ 1 ]B4.2.6—Saprotrophic nutrition
May 2016Paper1 ["HL"] · TZ024[ 1 ]B4.2.6—Saprotrophic nutrition
Practice this objective

Coverage 2016–2023 · Updated 15 Jul 2026

Concept essentials

  • Saprotrophs secrete enzymes onto dead organic matter.
  • Digested products are absorbed after external digestion.
  • Many fungi and bacteria are saprotrophic decomposers.
  • Saprotrophs recycle nutrients but energy is lost as heat.
ConceptIB Biology HL