Answer:
4 Charles Darwin was not able to explain the variation
B) A long time increase in the Earths Average temperature
Answer:
Blood enter the right atrium of the heart via the vena cava (superior and inferior)
The right atrium contracts to push the blood into the right ventricle through the triscupid valve
The contraction of the right ventricle pushes the blood through the pulmonary valve to the pulmonary artery which carries it to the lungs to be oxygenated
After oxygenation, the pulmonary vein brings blood to the left atrium
Contraction of the left atrium pushes the blood through the mitral valve into the left ventricle
The left ventricle contracts to push the blood through the aortic valve, into the aorta, which carries the blood through the body.
Explanation:
