Question

Which statement describes the net movement of carbon dioxide during internal respiration?

a. During internal respiration, carbon dioxide produced by cells diffuses into the bloodstream.
b. During internal respiration, carbon dioxide is released from the bloodstream into body tissues.
c. During internal respiration, carbon dioxide is completely removed from the body through the respiratory system.
d. During internal respiration, carbon dioxide is converted into oxygen within body tissues.

Answer 1

During internal respiration, carbon dioxide produced by cells diffuses into the bloodstream and is transported back to the lungs.

Step-by-step explanation:

During internal respiration, carbon dioxide produced by cells diffuses into the bloodstream. The partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. By the time blood returns to the heart, the partial pressure of carbon dioxide has returned to about 45 mm Hg. The blood is then pumped back to the lungs to be oxygenated once again during external respiration.