C1.3 Photosynthesis
Photosynthesis converts light energy into chemical energy by using pigments, thylakoid reactions and Calvin-cycle carbon fixation to build organic compounds from carbon dioxide.
- Syllabus
- First assessment 2025
- Topic
- C1.3
- Level
- HL
What you’ll learn
19 learning objectivesChoose one objective for a focused lesson, or study the complete topic.
Exam analysis
An aggregate view of how the complete C1.3 Photosynthesis appears across past papers.
Chance of appearing48%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper1
Most tested objectives
- C1.3.7—Limiting factors investigation14 questions
- C1.3.12 (HL)—ATP production in thylakoids10 questions
- C1.3.15 (HL)—Carbon fixation by Rubisco10 questions
Common question formats
- Calculation
- Comparison
- Data analysis
- Diagram interpretation
- Experimental design
- Graph interpretation
- Process explanation
- Structured response
- Definition or recall
Exam question appearances
November 2025Paper1B ["HL"] · TZ33(e)[ 1 ]C1.3.4—Photosynthetic pigment separation
November 2025Paper1B ["HL"] · TZ33(d)[ 2 ]C1.3.9 (HL)—Photosystems
November 2025Paper1B ["HL"] · TZ33(b)[ 1 ]C1.3.6—Absorption vs. action spectra
November 2025Paper1B ["HL"] · TZ33(a)[ 2 ]C1.3.6—Absorption vs. action spectra
May 2025Paper1A ["HL"] · TZ38[ 1 ]C1.3.8—CO₂ enrichment experiments
Practice this topic
9 original exam-style questions based on the patterns above.
Coverage 2012–2025 · Updated 15 Jul 2026