How much oxygen does a plant use up at night?

Question

Given the fact that plants cannot do photosynthesis at night but need respiration for their energy needs, they use up oxygen and generate carbon dioxide. But how much is this? If I fill a room with plants thoroughly, what composition will the air in this room be in the morning? Are different plant species vastly different in this regard?

Answer 1

Excellent question! While there is an overall net gain of released oxygen by the processes of photosynthesis and respiration, and because that ratio is consistent for every lap around the Krebs cycle, you would have to be able to measure precisely how many CO2 molecules were consumed during the day in order to calculate the precise ultimate net gain of 02. Generally speaking, however, in a sealed environment, the oxygen levels would rise fairly steadily and slowly in the room assuming temperature, light, and therefore photosynthetic rates stayed fairly consistent.