Biological Classification.
The classification system starts with a group with a wide variety of organisms and becoming more selective as the groups get more specific.
Additional information: Carl Linnaeus classified organisms by shared characteristics.
They help pump blood at a greater distance than Atria can.
The two semilunar valves, the pulmonary and aortic valves, are closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left.
