The most prominent of these (and historically the first) is the representation theory of groups, in which elements of a group are represented by invertible matrices in such a way that the group operation is matrix multiplication.
hemoglobin is able to perform this function due to its ability to reversibly bind to oxygen. inside oxygen rich areas of the lungs, hemoglobin picks up oxygen molecules, then it transports the oxygen via red blood cells to bodys tissue, once hemoglobin reached the oxygen poor area of the tissues it releases the oxygen.
The four subunits of hemoglobin actually bind to oxygen cooperatively, the binding of oxygen to one site of the four subunits will increase the likelihood of the remaining sites to bind with oxygen as well. Hemoglobin is a protein that is used to carry oxygen through the blood stream from the lungs to the tissues. This is important for survival. Hemoglobin has a lower affinity for oxygen the lower the concentration of oxygen gets. This has great implications for the human body and has helped us adapt very effectively.