<span>Protocooperation is where two species interact with each other beneficially; they have no need to interact with each other.</span>
Answer:
Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.
The left side of the heart collects oxygen-rich blood from the lungs and pumps it to the body. The left and right sides of the heart are divided by walls<span> called septums. There is an atrial septum that separates the right and left atriums, and a ventricular septum that separates the right and left ventricles.</span>
