C3 efficiency drops at high temperatures, while C4 plants stay efficient.
The decline in C3 plants is best explained by:
- Acheck_circle
Stomata close at high temperatures, so O2 builds up, and rubisco fixes O2 instead of CO2 (photorespiration)
- B
C3 plants lose chlorophyll permanently above 30 C
- C
The Calvin cycle stops because RuBP is unstable above 30 C
- D
C3 plants do not have ATP synthase at high temperatures
Explanation
At high temperatures, C3 plants close stomata, raising internal O2/CO2 ratio. Rubisco binds O2 (oxygenase activity), wasting energy via photorespiration.