What are the subunits of nucleic acids?

We want most cells to be even in and out which is called

Why do oceanic plates tend to subduction when colliding with a continental plate

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?