Final answer:
Xylem and phloem are both part of the plant's vascular system, with xylem transporting water and minerals upwards and phloem transporting sugars in both directions. The correct option is a.
Step-by-step explanation:
When you compare the structure and function of xylem to that of phloem, several key differences are observed. Both are essential components of the vascular system in plants, facilitating the transport of substances necessary for plant survival and growth. The xylem is primarily responsible for the upward transport of water and minerals from the roots to the rest of the plant. This is facilitated by a mechanism known as transpirational pull, which is a result of water evaporating from the leaves, creating tension that pulls more water from below.
The phloem, on the other hand, transports sugars, proteins, and other solutes both up and down the plant, depending on where they are needed. It operates based on pressure differences created by the loading and unloading of sugars, which also involves the movement of water into and out of the phloem cells.