Which best describes nitrogen fixation?
nitrogen fixation is the process of creating free nitrogen for plants to absorb.
nitrogen fixation is the breakdown of nitrogen in the soil.
nitrogen fixation is the conversion of nitrogen gas into a usable form.
nitrogen fixation is the destruction of the bonds between nitrogen and other elements.

After getting the slide and microscope ready, stella is eager to see the microscopic pond water specimen! she crouches around her microscope and aligns her eye with the microscope’s eyepiece. but she's only able to see a bright white light. at this point, no specimens or cells are visible on stella's pond water slide. after taking a moment to collect her thoughts, stella realizes she can't see any lifeforms because .

Epinephrine is a hormone released from the adrenal gland of the body, most often in a stressful situation. it is known as the "fight-or-flight" hormone. one way that it causes a response in the body is to activate receptors on muscle cells. where are these cellular receptors located? a. on the cell membrane b. in the nucleus c. on the cell wall d. around the mitochondria

A(n) is a molecule influences the way that a molecule reacts.