Which part of the plant's vascular system conducts water and dissolved minerals from roots to shoots?

• A. Xylem
• B. Phloem
• C. Cambium
• D. Cortex

Answer: (A)

Water and mineral transport from roots to shoots is carried by the xylem. Xylem tissue forms hollow, dead conduit cells—vessel elements and tracheids—that create continuous tubes from roots up through stems to the leaves. As water evaporates from the leaf surfaces (transpiration), a negative pressure pulls water upward through these tubes; the water columns are kept intact by the cohesion of water molecules and their adhesion to the tube walls. Minerals dissolved in that water are pulled along in the same upward flow, delivering nutrients to growing shoots and leaves. The phloem, by contrast, moves sugars and other organic nutrients from photosynthetic areas to where they’re needed or stored, and it can move in multiple directions depending on demand. Cambium is the meristem that produces new xylem and phloem during secondary growth, while cortex is a surrounding ground-tissue layer outside the vascular bundles that mainly serves storage and other functions rather than primary water and mineral transport.