The existence of a hydrostatic pressure gradient in phloem tubes can be accounted for by

Question

Quizplus · Accepted Answer

The existence of a hydrostatic pressure gradient in phloem tubes is primarily due to the loading of sugars into phloem at sources and removal of sugars at sinks. This creates a high solute concentration at sugar sources, which lowers the water potential and results in the movement of water from the xylem into the phloem. This increased pressure at the source end of the phloem tube drives the movement of sugars towards the sink end, where sugars are actively removed, resulting in a decrease in pressure. Therefore, the active transport of sugars creates a pressure gradient that drives the movement of nutrients in phloem tubes.

The Existence of a Hydrostatic Pressure Gradient in Phloem Tubes