Which of the following is NOT transferred by alveoli?

A. Oxygen

B. Blood

C. Carbon dioxide

D. Gases

Please select the best answer from the choices provided.

Answer

The correct answer is B. Blood.

Explanation

The alveoli are small air sacs in the lungs where the exchange of gases occurs. They facilitate the transfer of oxygen from the air into the bloodstream and the transfer of carbon dioxide from the blood to the air to be exhaled.

A. Oxygen: Transferred from the alveoli to the blood.

B. Blood: NOT transferred by the alveoli; blood flows through the lungs but does not pass through the alveolar walls. The exchange occurs only at the level of gases.

C. Carbon dioxide: Transferred from the blood to the alveoli to be exhaled.

D. Gases: This refers to both oxygen and carbon dioxide, which are exchanged in the alveoli.

Thus, the only substance listed that is not transferred by the alveoli is blood.