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IB Biology HL D2.2.9 Hl Epigenetic Tag Removal Questions

Analyse how parental methylation is erased after fertilization and how developmental methylation patterns are established in IB Biology HL D2.2.9.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain why removing parental DNA methylation after fertilization permits expression of genes needed for early development.
  • Interpret developmental methylation data to identify post-fertilization erasure of both parental methylation patterns before later tissue-specific modification.

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Study D2.2.9 (HL)—Epigenetic tag removal conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL D2.2.9 Hl Epigenetic Tag Removal Questions question 1

[Maximum number: 1]

DNA methylation profiles in zebrafish (Danio rerio) gametes were determined. The methylated areas were divided into three groups according to the amount of methylation: high, medium and low methylation.

Figure for Question IB Biology HL D2.2.9 Hl Epigenetic Tag Removal Questions question 1 — IB Biology HL

Methylation of DNA in sperm and egg is removed immediately after fertilization. What is the reason for this?

A

Methylation allows RNA polymerase to join the promoter.

B

It is needed to form homologous pairs of chromosomes.

C

It allows expression of genes linked to early development.

D

Transcription of promoters only occurs in methylated genes.

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