The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
Answer:
The earth is turning.
Explanation:
when the earth turns it causes the sun to move from one part of the sky to the other. The earth revolves around the sun. So when it become night time for example, the sun is just on the other side of the earth.
Cells is a basic unit of life
