Final answer:
Hemoglobin in the red blood cells is responsible for carrying oxygen and carbon dioxide. It binds oxygen to transport it to the tissues, and some carbon dioxide is carried back to the lungs bound to hemoglobin as carbaminohemoglobin.
Step-by-step explanation:
The substances that can be carried in the blood bound to hemoglobin include oxygen (O2) and carbon dioxide (CO2). Hemoglobin is a metalloprotein found in red blood cells, which consists of four subunits, each containing a heme group that binds oxygen. This binding enables each hemoglobin molecule to transport up to four oxygen molecules from the lungs to the tissues. Besides oxygen transport, hemoglobin can also bind carbon dioxide to form carbaminohemoglobin, which carries about 10 percent of the carbon dioxide from the bodily tissues back to the lungs for exhalation. Other substances like nitrogen, glucose, and water are transported in the blood but are not typically bound to hemoglobin.