water transport in plants

Water uptake is contolled by two mechanisms:

• root pressure
• cohesion tension

an osmotic gradient must be created in the roots for this process to occur. This is done in two ways. substances are either actively transported by the plant to the epidermal cells (root hair cells)or substances build up by diffusion. the building up of substances lower the water potential of the root hair cells, lower then the surrounding soil so that water enters the roots by osmos. osmosis continues to the endodermis due to neighbouring cells having a lower water potential. root pressure only occurs…