Final answer:
Water is transported from plant roots to leaves through a combination of osmotic pressure, cohesion and adhesion of water molecules, and the transpiration process, which is governed by the cohesion-tension theory and influenced by water potential.
Step-by-step explanation:
Water extending in tubes from plants roots to leaves is maintained by several processes including osmotic pressure, cohesion and adhesion, and transpiration. When water vapor is lost from the leaves via transpiration, it creates a negative pressure that pulls water up from the roots through the xylem. This movement is also supported by the cohesion-tension theory, where water molecules stick to each other (cohesion) and to the walls of the xylem vessels (adhesion). Plant roots absorb water and essential nutrients from the soil, which are then transported up to the leaves to support various metabolic functions and photosynthesis. Water potential plays a crucial role in this process, decreasing from the roots to the top of the plant which facilitates the upward movement of water.