C1.3.15 (HL)—Carbon fixation by Rubisco
Rubisco catalyses carbon fixation by attaching carbon dioxide to RuBP, forming glycerate phosphate at the start of the Calvin cycle.
- Syllabus
- First assessment 2025
- Objective
- C1.3.15
- Level
- HL
Exam analysis
Chance of appearing9%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–2
Common command terms
- State
- Describe
- Explain
- Identify
- Predict
Recent exam appearances
November 2024Paper2 ["HL"] · TZ05(a)[ 2 ]C1.3.15 (HL)—Carbon fixation by Rubisco
May 2024Paper2 ["HL"] · TZ18(c)[ 7 ]C1.3.15 (HL)—Carbon fixation by Rubisco
May 2024Paper2 ["HL"] · TZ26(c)[ 8 ]C1.3.15 (HL)—Carbon fixation by Rubisco
November 2023Paper1 ["HL"] · TZ227[ 1 ]C1.3.15 (HL)—Carbon fixation by Rubisco
May 2023Paper1 ["HL"] · TZ130[ 1 ]C1.3.15 (HL)—Carbon fixation by Rubisco
Practice this objective
Coverage 2015–2024 · Updated 15 Jul 2026
Concept essentials
- Rubisco catalyses carboxylation of RuBP.
- Carbon fixation produces glycerate 3-phosphate early in the Calvin cycle.
- The Calvin cycle occurs in the chloroplast stroma.
- Radioactive carbon tracing helped reveal the path of carbon through photosynthesis.