Each red blood cell carries about 250 million molecules of hemoglobin. If every hemoglobin molecules is attached to four oxygen molecules, how many oxygen molecules could one red blood cell carry?

One red blood cell will be able to carry one billion molecules of oxygen.

Explanation:

If each red blood cell carries 250,000,000 hemoglobin and every molecule of hemoglobin binds four oxygen molecules, the number of oxygen molecules carried by one red blood cell is 250,000,000 x 4 = 1,000,000,000. That is 1billion oxygen molecules is been carried by one red blood cell. Hemoglobin is a protein present in the red blood cell which binds and transports oxygen to the cells throughout the body. Hemoglobin has four binding sites for oxygen. The binding of one oxygen to its binding site on hemoglobin increases the binding affinity of subsequent oxygen molecules to the other binding sites on the hemoglobin. This phenomenon is known as cooperativity.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.