Biology / Unit 11 Bio 2545 short lesson, about 20 seconds
Transpiration and Stomatal Regulation
Captions available
The idea
Transpiration, water vapor loss at the leaf surface, drives xylem sap ascent but is regulated by guard cells opening and closing the stomata.
In practice
Guard cells close stomata under water stress, cutting transpiration loss but also blocking carbon dioxide needed for photosynthesis.
Where people slip
Up to 90 percent of water a root absorbs exits through transpiration — most absorbed water never becomes plant tissue.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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