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C1.3.19 (HL)—Interdependence of light and light-independent reactions

The light-independent reactions depend on ATP and reduced NADP made by light-dependent reactions to reduce fixed carbon into sugars, connecting the mechanism to observable photosynthesis evidence.

Syllabus
First assessment 2025
Objective
C1.3.19
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2021
Most common paperPaper1
Typical marks1–8

Common command terms

  • Explain
  • Distinguish

Recent exam appearances

November 2021Paper2 ["HL"] · TZ07(c)[ 7 ]C1.3.19 (HL)—Interdependence of light and light-independent reactions
May 2017Paper1 ["HL"] · TZ213[ 1 ]C1.3.19 (HL)—Interdependence of light and light-independent reactions
May 2013Paper2 ["HL"] · TZ15(c)[ 8 ]C1.3.19 (HL)—Interdependence of light and light-independent reactions
May 2012Paper1 ["HL"] · TZ130[ 1 ]C1.3.19 (HL)—Interdependence of light and light-independent reactions
Practice this objective

Coverage 2012–2021 · Updated 15 Jul 2026

Concept essentials

  • Light-dependent reactions produce ATP and reduced NADP.
  • The Calvin cycle uses ATP and reduced NADP to reduce fixed carbon.
  • Light-dependent reactions occur in thylakoids, while the Calvin cycle occurs in stroma.
  • The two stages depend on exchange of energy carriers and reduced carriers.
ConceptIB Biology HL