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D1.1 DNA replication

DNA replication copies genetic information through template strands, complementary pairing, enzyme action, proofreading, and laboratory amplification or separation techniques used to analyse DNA.

Syllabus
First assessment 2025
Topic
D1.1
Level
SL

Exam analysis

Chance of appearing28%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper1
Typical marks1–2

Most tested objectives

Common question formats

  • Definition or recall
  • Diagram interpretation
  • Structured response
  • Process explanation
  • Calculation
  • Data analysis
  • Comparison

Recent exam appearances

November 2025Paper1A ["SL"] · TZ37[ 1 ]D1.1.3—Role of helicase and DNA polymerase
November 2025Paper2 ["SL"] · TZ32(b)[ 1 ]D1.1.4—PCR and gel electrophoresis
May 2025Paper2 ["SL"] · TZ38(b)[ 4 ]D1.1.4—PCR and gel electrophoresis
May 2025Paper1A ["SL"] · TZ37[ 1 ]D1.1.4—PCR and gel electrophoresis
May 2025Paper1A ["SL"] · TZ26[ 1 ]D1.1.2—Semi-conservative replication
Practice this topic

Coverage 2010–2025 · Updated 16 Jul 2026

Objective notes

5 learning objectives
D1.1.1DNA replication

• Produces exact DNA copies before cell division

• Maintains genetic continuity for reproduction, growth, and tissue replacement

D1.1.2Semi-conservative replication

• Each new DNA molecule has one original strand and one new strand

• Complementary base pairing gives accurate copying; Meselson-Stahl isotope evidence supports the model

D1.1.3Role of helicase and DNA polymerase

• Helicase unwinds DNA and breaks hydrogen bonds between strands

• DNA polymerase joins complementary nucleotides to build new strands

D1.1.4PCR and gel electrophoresis

• PCR amplifies selected DNA using primers, temperature cycles, and Taq polymerase

• Gel electrophoresis separates DNA fragments by size and charge

D1.1.5Applications

• PCR and gel electrophoresis support DNA profiling

• Applications include forensic identification and paternity testing

ConceptIB Biology SL