Hemoglobin carries oxygen to the cells and takes carbon dioxide away from the cells.

Here's a breakdown:

* Oxygen: Hemoglobin in red blood cells binds to oxygen in the lungs, where the oxygen concentration is high. This oxygen-rich blood is then transported throughout the body, delivering oxygen to the cells.

* Carbon Dioxide: As cells use oxygen for energy production, they produce carbon dioxide as a waste product. This carbon dioxide enters the bloodstream and binds to hemoglobin, which then transports it back to the lungs to be exhaled.

This continuous cycle of oxygen delivery and carbon dioxide removal is crucial for maintaining life.