Answer:
b. causes constriction of cerebral blood vessels in response to a drop in systemic blood pressure
Explanation:
No matter what happens or fluctuations occur in the blood pressure of body the blood pressure to the brain is always kept constant by the necessary changes and means possible. The blood value is always maintained at 50mL per 100g of Brain Tissue. The constriction of blood vessel keep the blood pressure normal to the brain in case of low blood pressure. Otherwise, it can have deadly consequences.
They loosen up to be tighten again
It destroys the quality of soil
it kills the useful micro organisms present in the soil
A shell is considered as biotic (living) because it is a hard, rigid covering of many animals such as snail, sepia, pila, turtles, sea urchins. A shell is protective outer layer of these soft bodied animals.