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C1.3.7—Limiting factors investigation

Photosynthesis rate is limited by whichever required factor is least available, commonly light intensity, carbon dioxide concentration or temperature, connecting the mechanism to observable photosynthesis evidence.

Syllabus
First assessment 2025
Objective
C1.3.7
Level
HL

Exam analysis

Chance of appearing9%of analysed past papers
Latest appearanceMay 2022
Most common paperPaper2
Typical marks1–2

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Recent exam appearances

May 2022Paper1 ["HL"] · TZ19[ 1 ]C1.3.7—Limiting factors investigation
November 2021Paper2 ["HL"] · TZ01(c)[ 2 ]C1.3.7—Limiting factors investigation
November 2020Paper3 ["HL"] · TZ03(c)[ 1 ]C1.3.7—Limiting factors investigation
November 2020Paper3 ["HL"] · TZ03(b)(ii)[ 3 ]C1.3.7—Limiting factors investigation
November 2020Paper3 ["HL"] · TZ03(b)(i)[ 1 ]C1.3.7—Limiting factors investigation
Practice this objective

Coverage 2013–2022 · Updated 15 Jul 2026

Concept essentials

  • Photosynthesis rises with a limiting factor only while that factor restricts the rate.
  • Light intensity, carbon dioxide concentration and temperature are common limiting factors.
  • A plateau on a rate graph indicates that another factor has become limiting.
  • Photosynthesis rate can be measured by oxygen production, carbon dioxide uptake, pH change or biomass gain.
ConceptIB Biology HL