() earth's atmosphere was primarily composed of until the proterozoic era

a. oxygen

b. nitrogen

c. methane

d. carbon dioxide

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

The tubes transporting minerals and water upward are called ?

Why does it matter if osmosis is put into a “scab” or a “nosebleed? ” where would that leave him?