C3 pathway
Dark reactions (Calvin cycle) · Biology
Study notes
A wheat leaf on a cool, moist morning fixes CO2 directly into 3-carbon PGA — the classic C3 pattern. But at noon when stomata close and oxygen builds up, RuBisCO starts grabbing O2 instead of CO2 (photorespiration), wasting up to 25% of the plant's effort — the hidden tax C3 plants pay.