Why is the nucleus considered the power house of the cell

Explain how organisms could be harmed by high levels of salt from roadways?

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?

Which describes the changes in the earths motion?