Answer:
Explanation:
1) Excitation brings about contraction.
2) Contraction leads to an increase in blood pressure.
3) Changes in blood pressure results in the opening and closing of the heart valves.
4) The opening and closing of heart valves then regulates the flow of blood and it's volume.
Answer:
is the surface where the water pressure head is equal to the atmospheric pressure
Explanation:
is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water.
Answer:
tissues that is responsible for the secondary growth of stems and roots.
