Final answer:
Almost all of the oxygen consumed during breathing is converted to carbon dioxide and water. Oxygen is transported by hemoglobin in the blood to body tissues, where it is used for metabolism, and carbon dioxide is transported back to the lungs to be exhaled.
Step-by-step explanation:
Almost all of the oxygen (O2) one consumes in breathing is converted to carbon dioxide (CO2) and water (H2O). In the body, oxygen is used by cells in a process called cellular respiration, where it is the final electron acceptor in the electron transport chain. The oxygen is used to oxidize nutrients, like glucose, to produce energy for the cells in the form of adenosine triphosphate (ATP). The oxidation of nutrients leads to the production of carbon dioxide and water as waste products, which are excreted from the body.
Oxygen is transported from the lungs to the tissues primarily through the binding with hemoglobin in red blood cells. As the blood passes through the body's tissues, oxygen is released from the hemoglobin and moves into the cells, where it is used for cellular metabolism. The carbon dioxide produced as a result of this metabolism is then carried back to the lungs via the blood, where it is expelled from the body through exhalation.