What is respiration?

What is respiration?

• A. The release of energy from food
• B. The transport of oxygen in the blood
• C. The breakdown of carbohydrates
• D. The exchange of carbon dioxide for oxygen (breathing)

Answer: (D)

Respiration in this sense means breathing—the process of taking in oxygen and getting rid of carbon dioxide. When you inhale, oxygen-rich air reaches the lungs and oxygen passes into the blood. When you exhale, carbon dioxide, a waste product of metabolism, leaves the blood and is breathed out. This gas exchange between the air and the bloodstream is what respiration refers to here. The other ideas describe cellular processes inside cells (like energy production from food or breakdown of carbohydrates) or the job of the circulatory system, but they are not the act of breathing itself.

Respiration in this sense means breathing—the process of taking in oxygen and getting rid of carbon dioxide. When you inhale, oxygen-rich air reaches the lungs and oxygen passes into the blood. When you exhale, carbon dioxide, a waste product of metabolism, leaves the blood and is breathed out. This gas exchange between the air and the bloodstream is what respiration refers to here. The other ideas describe cellular processes inside cells (like energy production from food or breakdown of carbohydrates) or the job of the circulatory system, but they are not the act of breathing itself.