1.what is the meaning of synapse
2.explain how an impulse is transmitted across a synapse

19. scientists use meteorites that hit earth to provide evidence of the composition of earth's interior because they hypothesize that

What did hunter gathers do to alter the environment?

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen