Which term is the protein that carries oxygen in the blood?

Which term is the protein that carries oxygen in the blood?

• A. Hemoglobin
• B. Hemorrhage
• C. Ethanol
• D. Alcohol

Answer: (A)

Oxygen transport in the blood is carried by a protein inside red blood cells that binds oxygen through iron-containing heme groups. In the lungs, oxygen attaches to this protein; in tissues, it is released where needed, while the protein also helps carry some carbon dioxide back to the lungs. That protein is hemoglobin. The other terms refer to different things—hemorrhage means bleeding, ethanol is a type of alcohol, and alcohol is a broad class of chemicals; none describe the oxygen-carrying protein in the blood.

Oxygen transport in the blood is carried by a protein inside red blood cells that binds oxygen through iron-containing heme groups. In the lungs, oxygen attaches to this protein; in tissues, it is released where needed, while the protein also helps carry some carbon dioxide back to the lungs. That protein is hemoglobin. The other terms refer to different things—hemorrhage means bleeding, ethanol is a type of alcohol, and alcohol is a broad class of chemicals; none describe the oxygen-carrying protein in the blood.