MadSci Network: General Biology

Re: How does oxygen enter the leaves of a plant at night?

Date: Sun Oct 15 23:16:38 2000
Posted By: Evelyn Tsang, Research Assistant
Area of science: General Biology
ID: 970826219.Gb

Hi there,

I think your question is about plant respiration.  

You are right that stomata are open during the day, when the plant is 
photosynthesizing, and closed at night, as in when sunlight is absent. 
Gas exchange at the stomatal pores is to allow CO2 to diffuse in, and for 
the by-product oxygen to diffuse out for the process of photosynthesis.

Plant respiration uses up oxygen and produces carbon dioxide.  Oxygen is 
dissolved in aqueous solutions (at 25C, the concentration is 250uM) and is 
available in the intercellular spaces of the plant.  The amount of oxygen 
required in respiration is around 1uM so there is no lack of oxygen for 
the plant cells in daytime or nighttime.

Thanks for your question!

my references came from textbooks and the internet:

1.(oxygen concentrations) Taiz & Zeiger "Plant Physiology" 1991.
2.(general overview) ht
3.(in-depth lecture)

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