ISA Certified Arborist Practice Exam

Tree sap plays a vital role in the physiology of a tree, primarily through its function in transporting nutrients and providing energy storage. Sap is comprised of water, sugars, hormones, and minerals, which are essential for the tree's growth and development. This liquid moves through the vascular system, specifically within the xylem and phloem. The xylem transports water and dissolved nutrients absorbed from the soil, while the phloem is responsible for distributing the sugars produced during photosynthesis to various parts of the tree.

In addition to nutrient transport, the sugars stored in the sap serve as an energy reserve, which the tree can use during periods of growth or stress when immediate access to energy is required. This dual role of sap—transportation and energy storage—is crucial for the tree’s overall health and functioning.

The other options do not encompass the full significance of tree sap. While it may play a minor role in aiding leaf production or have some effects on pest prevention, the primary roles of nutrient transport and energy storage are the most critical functions of tree sap. Structural support is mainly provided by the tree's wood and cellular structure, rather than by sap itself.