Summary
Shouldn't trees have a height limit? Water can only be sucked up a tube that's less than 10 meters, so how do roots transport water all the way up an 11 meter tree? Unlike in gasses, there can actually be negative pressures (less than a vacuum) in liquids. The xylem tubes are so thin that the surface tension is strong enough to keep the meniscus from breaking. Usually, at such low pressures, the water in the tubes would spontaneously boil. However, there are no air bubbles - ever - in the tube, which means that there is no site for the liquid to turn to gas. Also, most of the water sucked up by a tree's roots simply evaporates instead of being used for cellular processes.
Significance
We're currently studying plants, and this video gives detailed background into the process of transpiration and how the water can be sucked up a plant thats hundreds of feet tall.
Video Info
YouTube Link
Author: 1veritasium
Date of Publication: October 30th, 2012
Is the tree constantly sucking in water or are there periods where only air travels up the xylem?
ReplyDeleteWhy does the water start to boil in the straw after reaching 10 meters?
ReplyDelete