Why sex is important for our life's?

equal distribution i think.

and after water is usually warmed by the sun the water temperature raises and then evaporates .

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.