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D2.2.9 (HL)—Epigenetic tag removal

Epigenetic tag removal resets many parental methylation patterns after fertilization, allowing early developmental genes to be expressed in embryos and tissues.

Syllabus
First assessment 2025
Objective
D2.2.9
Level
HL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper1
Typical marks1–3

Recent exam appearances

May 2023Paper1 ["HL"] · TZ126[ 1 ]D2.2.9 (HL)—Epigenetic tag removal
May 2016Paper1 ["HL"] · TZ06[ 3 ]D2.2.9 (HL)—Epigenetic tag removal
Practice this objective

Coverage 2016–2023 · Updated 16 Jul 2026

Concept essentials

  • Many parental methylation patterns are erased after fertilization.
  • Demethylation can allow early developmental genes to be expressed.
  • New tissue-specific methylation patterns form later in development.
  • Some imprints can escape complete resetting and affect offspring expression.
ConceptIB Biology HL