C4.2.21—Dependence between respiration and photosynthesis Topic Practice
C4.2.21—Dependence between respiration and photosynthesis Topic Practice

IB Biology syllabusBiology SL/HLFirst assessment 2025
Students practise linking gas exchange between photosynthesis and respiration to explain O₂ and CO₂ cycling in ecosystems.
How this is tested
- explain how chloroplasts and mitochondria form a reciprocal gas exchange system using O₂ and CO₂ as substrates
- interpret net gas exchange data from light
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