Which statement about oxygen transport in blood is correct?

Which statement about oxygen transport in blood is correct?

• A. Most oxygen is transported bound to albumin.
• B. Most oxygen is carried by hemoglobin.
• C. Oxygen dissolves readily in plasma with no carrier protein.
• D. Oxygen is transported primarily by leukocytes.

Answer: (B)

Oxygen transport relies on hemoglobin inside red blood cells to move most of the gas. In the lungs, oxygen binds to the iron in the heme groups of hemoglobin, forming oxyhemoglobin, so one hemoglobin molecule can carry up to four oxygen molecules. In tissues, where oxygen pressure is lower and carbon dioxide and hydrogen ions are higher, hemoglobin releases the bound oxygen so cells can use it for metabolism. The dissolved portion of oxygen in plasma is small because oxygen is not very soluble in blood—only a tiny fraction is carried this way, while the majority travels bound to hemoglobin. Albumin is a plasma protein that carries various substances like fatty acids and hormones, not oxygen. Leukocytes are immune cells and do not transport oxygen. So the statement that most oxygen is carried by hemoglobin correctly reflects how the body efficiently moves O2 from lungs to tissues.

Oxygen transport relies on hemoglobin inside red blood cells to move most of the gas. In the lungs, oxygen binds to the iron in the heme groups of hemoglobin, forming oxyhemoglobin, so one hemoglobin molecule can carry up to four oxygen molecules. In tissues, where oxygen pressure is lower and carbon dioxide and hydrogen ions are higher, hemoglobin releases the bound oxygen so cells can use it for metabolism. The dissolved portion of oxygen in plasma is small because oxygen is not very soluble in blood—only a tiny fraction is carried this way, while the majority travels bound to hemoglobin. Albumin is a plasma protein that carries various substances like fatty acids and hormones, not oxygen. Leukocytes are immune cells and do not transport oxygen. So the statement that most oxygen is carried by hemoglobin correctly reflects how the body efficiently moves O2 from lungs to tissues.