Answer:
2. Oxygenin blood: Iron is an essential element for blood production. About 70 percent of your body's iron is found in the red blood cells of your blood called hemoglobin and in muscle cells called myoglobin. Hemoglobin is essential for transferring oxygen in your blood from the lungs to the tissues.
4.Nitrogen: Nitrogen is in the air that we breathe into our lungs but only the oxygen in the air is transferred from the lungs to the bloodstream and nitrogen is breathed out as a waste product. ... So our red blood cells are adapted to carry Oxygen, whereas Nitrogen dissolves in tiny amounts.