What is the driving force for the movement of solutes in the phloem of plants?

Question

Quizplus · Accepted Answer

The movement of solutes in phloem is driven by a difference in water potential (Ψ) between the source, where sugar is produced and loaded into the phloem, and the sink, where sugar is actively unloaded and consumed by the plant or stored. This is known as the pressure-flow hypothesis, where solutes flow from an area of high pressure (source) to an area of low pressure (sink). Gravity, root pressure, and transpiration of water through stomata do not play a significant role in the movement of solutes in phloem.

What Is the Driving Force for the Movement of Solutes