C4.2.20—Keeling Curve analysis
Keeling Curve analysis explains how energy flow, matter cycling, trophic transfer or carbon movement is represented, measured or limited within ecosystems.
- Syllabus
- First assessment 2025
- Objective
- C4.2.20
- Level
- HL
Exam analysis
Chance of appearing2%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1
Typical marks1
Common command terms
- Identify
Scoring notes
- Common mistake
- Reversing photosynthesis and respiration arrows in carbon-cycle diagrams.
Recent exam appearances
May 2025Paper1A ["HL"] · TZ336[ 1 ]C4.2.20—Keeling Curve analysis
November 2024Paper1 ["HL"] · TZ017[ 1 ]C4.2.20—Keeling Curve analysis
Practice this objective
Coverage 2024–2025 · Updated 16 Jul 2026
Concept essentials
- Keeling Curve analysis must be linked to the correct source, store, transfer or loss process.
- The evidence for keeling curve analysis depends on distinguishing energy flow from matter cycling.
- Keeling Curve analysis is clearer when arrows, units and trophic positions match the biological process.
- Data or diagrams for keeling curve analysis need interpretation as ecosystem transfer evidence.