Final answer:
Water is transported from the roots to the leaves of a pine tree by transpiration, where it evaporates and creates negative pressure in the xylem. This pressure, combined with the cohesive and adhesive properties of water, allows water to rise even in very tall trees.
Step-by-step explanation:
Water moves up a 100-foot pine tree from the roots to the leaves primarily through a process called transpiration. This process involves the evaporation of water from plant leaves, which creates a negative pressure in the xylem vessels. The cohesive forces among water molecules and adhesion to the xylem walls allow water to be pulled up as a continuous column from the roots to the leaves. Capillary action also plays a role in this ascent through the narrow tubes of the xylem. The unique molecular structure of water, with its capability for hydrogen bonding, allows for these cohesive and adhesive properties, which are crucial for the movement of water against gravity.
In tall trees, such as the California redwood, the same principles apply. The movement of sap, which is mainly water with dissolved nutrients, is propelled upwards by the strong cohesive forces between water molecules. Despite the height, evidence has shown that the negative pressure generated by transpiration is sufficient to move water to the tops of even the tallest trees.