What is the structure and and function of the mitochondria?

Astudent is looking through a microscope at some cells of an onion root tip. many of these cells are undergoing division since the root tip grows quickly and requires more cells. which cell most recently underwent metaphase? w x y z

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000

Why does the earth spin slowly, not faster? is it possible to prove it scientifically? can you prove it with math?