Certified Arborist Practice Test

The xylem is the vascular tissue in trees responsible for the transport of water and minerals from the roots to the rest of the plant. This transport is crucial for maintaining hydration, supporting photosynthesis, and delivering essential nutrients absorbed from the soil. Water movement through the xylem occurs through a process called transpiration, where water evaporates from the leaves, creating a negative pressure that pulls more water upward from the roots.

Carbohydrates, on the other hand, are primarily transported through the phloem, not the xylem. Photosynthates, which include sugars produced during photosynthesis, are also moved via the phloem to various parts of the tree where energy is needed. Hormones have their own transport pathways and while they can move through both xylem and phloem, they are not the primary substances that xylem is known for transporting. Therefore, the correct understanding of the xylem's function clarifies why water and minerals are its main transport materials.