Which statement accurately describes the function of the respiratory system?

• A. It takes in oxygen and removes carbon dioxide from the body.
• B. It pumps blood to the lungs.
• C. It digests nutrients for energy.
• D. It stores minerals for the body.

Answer: (A)

Breathing’s main job is gas exchange: it brings in oxygen that the body's cells need and removes carbon dioxide that cells produce as a waste product. In the lungs, oxygen moves from the air into the blood through the tiny air sacs called alveoli, while carbon dioxide travels from the blood into the alveoli to be exhaled. This oxygen-rich blood is then circulated to tissues to fuel metabolism, and carbon dioxide returns in the blood to be expelled. That single system handles both intake of oxygen and removal of carbon dioxide, so its description is: it takes in oxygen and removes carbon dioxide from the body.

Pumping blood to the lungs is done by the heart and is part of the circulatory system. Digesting nutrients is the job of the digestive system. Storing minerals is handled by the bones and other tissues, not the respiratory system.