What During the systole phase of the cardiac cycle the left ventricle contracts and blood is pumped into the aorta. Which of these valves prevents a backflow of blood into the left atrium aortic valve?

During the systole phase of the cardiac cycle, the left ventricle contracts, pushing blood into the aorta through the aortic valve. The valve that prevents backflow of blood into the left atrium is the mitral valve, not the aortic valve. The aortic valve ensures that blood flows forward into the aorta and does not return to the ventricle.