Question

Wildlife researchers study how tall trees transport water from roots to leaves against gravity, with some redwoods reaching over 300 feet in height. What mechanism enables this impressive upward water transport in tall trees?
Question 3 options:

Tree roots actively pump water upward using cellular energy like a mechanical water pump system

Transpiration from leaves creates tension that pulls water up through xylem vessels in a continuous column

Gravity actually helps water move upward in tall trees through specialized plant physics principles

Water flows upward because plant cells are lighter than water, creating natural buoyancy effects

Answer 1

Transpiration from leaves creates tension that pulls water up through xylem vessels in a continuous column.

Explanation: evaporation of water from leaf surfaces lowers the pressure in the leaf xylem, creating a negative pressure (tension) that pulls water upward. Cohesion between water molecules and adhesion to xylem walls keep an unbroken water column. The process is driven by sunlight and the physical properties of water (cohesion–tension), not by a mechanical pump in the roots, gravity helping, or buoyancy of cells.