The ultimate source of energy for physical life on earth is the sun

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?

Can i get the answer to this problem?

Explain how the concentration gradient affects the process of atp synthesis