<span>The answer is a certain required chemicals must be actively
transported. Blood brain barrier is a
selective membrane that separates blood circulating from the brain and the
fluid of extracellular in the central nervous system. This is also called a
filtering mechanism, the capillaries that carry blood to the brain and spinal
cord tissue blocking the path way of the certain substance.</span>
He observed 15 different finch species that originated as one ancestral bird. all differing in body shape, beak size, and mating habbits
Answer:
Do further testing on the species to discover whether or not the species is related.
Explanation:
Narcotics mimic the brain’s internal system....
Answer:
oxygen and carbon dioxide
