Entire exam will be graded again. Last time we learned that water moves through a plant due to cohesion of water molecules to each other and to sides of vessels and tracheids. It is pulled up under considerable tension. Wood is strong because it is made up of the combined primary and secondary cell walls of many tracheids, vessels and fibers.
Plants are able to close stomata.
Increased potassium ion concentration causes water to flow into guard cells, making them turgid carbon dioxide concentration in the leaf. Some plants open stomata at morning time even if moved into a dark closet. In lab, we worked with excised stems. In reality, though, roots control what ions enter the xylem stream. Might find some things in cortex of root that wouldn t be higher up in plant.