Elodea sprigs were sealed in tubes of pond water at 22 degrees C and exposed to lamps of increasing intensity. The number of O2 bubbles released per minute was counted as a proxy for photosynthetic rate.
Beyond about 20,000 lux, the rate plateaus. The most likely limiting factor at high intensity is:
- A
O2 bubbles are reabsorbed
- B
Light intensity continues to limit the reaction
- Ccheck_circle
CO2 availability or another non-light factor
- D
Chlorophyll concentration drops as light increases
Explanation
When increasing a single factor stops increasing rate, a different factor (commonly CO2 or temperature) limits the reaction. This is the principle of limiting factors.