Final answer:
In plants, roots absorb water and minerals, stems support and transport nutrients, and leaves conduct photosynthesis. Xylem transports water and minerals upwards, while phloem distributes sugars throughout the plant.
Step-by-step explanation:
The structures of plant roots, stems, and leaves are integral to a plant's ability to transport water, nutrients, and photosynthates. The xylem is responsible for the one-way transport of water and minerals from the roots to the rest of the plant, while the phloem carries sugars produced in the leaves to other parts where they are needed, such as growing regions or storage tissues. The leaves, as the site of photosynthesis, contain vascular bundles with both xylem and phloem to facilitate these transport processes. Water potential, along with transpirational pull, are key to the functioning of xylem. Phloem transport does not rely solely on water potential, but rather on a source-to-sink pressure flow mechanism where sugars move from areas of high concentration to areas of low concentration (sinks).