Question

In external respiration,

• A. Food is broken down and oxygen is absorbed.
• B. Food is broken down and carbon dioxide is produced.
• C. Oxygen is ejected and carbon dioxide is adsorbed.
• D. None of the above.

Answer 1

The correct option is D None of the above.

External respiration also known as breathing refers to a process of inhaling oxygen from the air into the lungs and expelling carbon dioxide from the lungs to the air. Exchange of gases both in and out of the blood occurs simultaneously. External respiration is a physical process during which oxygen is taken up by capillaries of lung alveoli and carbon dioxide is released from blood. Internal respiration or tissue respiration/cellular respiration refers to a metabolic process in which oxygen is released to tissues or living cells and carbon dioxide is absorbed by the blood. Once inside the cell the oxygen is used for producing energy in the form of ATP or adenosine triphosphate. Therefore, the correct answer is option D.