Limits on photosynthesis

The bubble counts and indicator colours come from a teaching model of the expected results, not from a real plant. Real counts vary more, bubbles differ in size and not all of the gas is oxygen, so counting bubbles is only a rough measure of the rate.

Lamp distance is not the same as light intensity: the light reaching the plant gets dimmer quickly as the lamp moves away. The 2 minutes to settle, each one-minute count and the 4 hours under the lamp run faster than real time.