Question

Carbon dioxide moves out of blood and into the alveolus while oxygen moves into the blood from the alveolus. Why does it happen so?

• A. The concentration of oxygen and carbon dioxide is higher in alveolus compared to incoming blood.
• B. The concentration of oxygen and carbon dioxide is lower in alveolus compared to incoming blood.
• C. The concentration of oxygen is higher and carbon dioxide is lower in alveolus compared to incoming blood.
• D. The concentration of oxygen is lower and carbon dioxide is higher in alveolus compared to incoming blood.

Answer 1

The correct option is D

The concentration of oxygen is lower and carbon dioxide is higher in alveolus compared to incoming blood.

Air in the lungs has a higher concentration of oxygen than blood entering the alveolus. Thus, oxygen moves into the blood from the lungs. The opposite is true for carbon dioxide where air in the lungs has a lower concentration of carbon dioxide. Thus, carbon dioxide moves out of blood and into the air present in the alveolus.