Answer:
There is no mixing of oxygen-rich and oxygen-poor blood.
- -
The right atrium and right ventricle of the human heart pump oxygen-poor blood to the lungs and the left atrium receives oxygen-rich blood. They never mix.
C It controls what is allowed to enter or leave the cell.
Natural selection can cause speciation, which increases the biodiversity of an ecosystem. Several bacterial colonies are placed on a petri dish that contains agar with antibiotics. After 24 hours, ninety percent of the original bacteria die, but the remaining ten percent survive and later reproduce.
