As an impulse travels down an axon,

a chemical signal is released

a charge reversal occurs

electrons are transported

the signal stops

What was the land like over 500 million years ago? what was under the sea?

Which statement is true for bacteria a. bacteria have complex internal structures b. all bacteria are spiral in shape c. all bacteria cause disease in animals d. bacteria break down some foods

This is collection of data made by comparing objects in standard units. in science, the units are metric.