Question

Once water is absorbed by plant roots, it has to travel against gravity through xylem. How do the dead cells of the xylem work together with the living cells of leaves at the top to keep the water moving?

Answer 1

Water travels upward in plants through a mechanism known as transpiration pull. The xylem is composed of dead cells that create continuous hollow tubes, allowing water to easily flow from roots to leaves. Living cells in leaves lose water by transpiration (stomatal evaporation). This loss of water generates a suction force (pull) at the top, pulling more water upward through the xylem. Cohesion (attraction between water molecules) and adhesion (attraction to xylem walls) contribute to a continuous water column. Thus, dead xylem cells supply the channel, while living leaf cells generate the pull, allowing water to move against gravity.