Why is osmosis important to internal transport in plants?

Question

Why is osmosis important to internal transport in plants?

Answer 1

When plants move sugars through translocation, the sugars are actively loaded into the phloem cells.  This creates a lower concentration of water in the cell than out, which causes water to move in by osmosis.  This causes the cell to have a high internal pressure (turgor pressure) which is relieved by passing the sugar solution into the adjacent cell.  This continues up (or down, depending on time of year) the phloem until the sugars get to their sink.

Osmosis is also necessary for moving water and dissolved minerals through the xylem.  When the concentration of water is greater in the soil than the outer layer of root cells, water will move into the cells through osmosis. Then, water will move to adjacent root cells with lower water concentrations.  It will continue this movement as long as there are adjacent cells with lower water concentrations and therefore can continue water movement up the entire plant.