how do plants respire when the stomata are closed?

Answer 1

Even when stomata are closed, some oxygen can get into the plant and is found within tissues. Also, plants cope because when stomata are closed they reduce their metabolism so that they don't need to respire as much - that's why plants in hot or dry places grow so slowly - their metabolism is slow. We do the same if our nose and mouth are covered with water then our metabolism automatically slows down to make the air in our lungs last longer!

Lets not confuse this with photosynthesis - some plants have special adaptations to store carbon dioxide so that they can photosynthesise when stomata are closed during the day. But all plants need to respire all the time (ie not only during the day) and they do not have adaptations to store oxygen in this way.

Hope that helps xx

Answer 2

In a nutshell, 24-hour CAM occurs by phosphoenol pyruvate (PEP) carboxylase fixing over the night to form malic aicd that is stored in plant cell vacuoles. While stomata are tightly closed the following day, malic acid is decarboxylated releasing CO2 for C3 photosynthesis.
meaning plants can respire while their guard cells i.e stomata are closed

Answer 3

thru Guttation at night