Of course, both shammydodger and drestie are correct. My emphasis was on a different understanding of the question's intent. Living plant cells survive the night-time and cloudy days by respiration,(but does take place at other times as well) most of which takes place in the cell's mitochondria... my focus was on the dual purpose of transpiration...refrigerating the plant and carrying, towards the leaves, the nutrients coming from the roots... Thanx for straightening that out!