Explain the reason(s) why the presence of iridium tells scientists that a meteorite impact caused the mass extinction of dinosaurs?​

Environmental differences within ecosystems are generally caused by

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

What is a group of organisms that are closely related and share similar characteristics