1. Concentration gradient. The difference in the concentration on both sides of the semipermeable membrane.
2. Pressure gradient - Pressure difference between two solutions.
Why the water is forced to move through cell membrane beyond endodermis ?
Water is forced to move through cell membranes beyond endodermis because of the suberin (waxy substance) present on radial walls of endodermal cells blocks water and solute movement through cell walls of endodermis.