A microscope because it needs to be magnified
Answer:
There are several hypotheses as to why Earth's climate changed: an ice age and a meteor collision are two. Regardless of why the climate changed, dinosaurs could not adapt to a new environment to avoid extinction. Mammals did not become a dominant species on Earth until the extinction of dinosaurs.
The parasympathetic nervous system is characterized by the location preganglionic neurons and the short postganglionic axons near the organs they innervate. The preganglionic neurons would originate in the spinal cord or the brainstem while the postganglionic neurons would lie outside the CNS.
Internal means its on the inside
external means its on the outside
so an internal regulator is when the proteins respond to events on the inside of a cell
and an external regulator is when the proteins respond to events outside the cell