Why are complex carbohydrates better for storing energy than simple sugars are?

Which format should he use to present his data?

Dna is colied into chromosomes in a cell

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?