Iron (Fe) is a trace element that contributes to the composition of the protein called Hemoglobin. Hemoglobin is carried in red blood cells. Hemoglobin's main job is to carry oxygen throughout the body. So, when a person does not have enough iron in their body, they will begin to feel drowsy and fatigued, because the proper amount of oxygen is not available. This condition is called Anemia.
iron
Iron is the element that is a necessary part of hemoglobin.
Iron and carbon
Iron.
Iron (Fe)
iron
iron
Iron
Basically hemoglobin is intended for oxygen transport from lungs to brain, muscle and whole body as needed...
Red blood cells contain hemoglobin and transport oxygen
to transport oxygen
A protein (hemoglobin) is required to transport Oxygen around the body.
Iron is bound to the center of hemoglobin, which transports oxygen. Depending on the meaning of element in the question, it could be Iron(most likely) or hemoglobin. ADDED: It is the iron: 4 iron molecules held within the haemoglobin molecule's hydrocarbon lattice. The oxygen binds physically to the Fe without reacting chemically.
The Earthworm.
It is an iron-based protein called hemoglobin.
hemoglobin
which permits them to transport oxygen and carbon dioxide
Hemoglobin
hemoglobin