Translocation is the movement of dissolved substances or assimilates through the plant. It requires energy and occurs in the Phloem. It moves from the Source: where it is made, a high concentration to the Sink: where it is used up, a low concentration. Enzyme maintain the concentration gradient from the source by breaking down the solutes at the sink.
The Mass Flow Hypothesis:
Scientists are really sure how translocation occurs but the mass flow hypothesis is the most supported.
At the Source:
Sugars are loaded into the Phloem by Companion cells, the water potential decreases, the water moves down, hydrostatic pressure increases the sugars flow to the Sink.
At the Sink:
Solutes are stored by enzymes inside the storage cells. This increases the water potential meaning that the water also leaves.
Companion Cells (at the Source):
These contain large numbers of mitochondria making the 'A' 'T' 'P' needed for the active transport part of…