JAMB Biology 2025 Objective — Question 2
Question 2 of 40 from the Joint Admissions and Matriculation Board (JAMB) Biology 2025 Objective paper, with the correct answer and a full explanation.
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In human lungs, gas exchange takes place across a thin barrier between the alveoli and capillaries. Which statement about this exchange is correct?
- A. Carbon dioxide diffuses into the blood and oxygen diffuses into the alveoli
- B. Oxygen diffuses into the blood and carbon dioxide diffuses into the alveoliCorrect
- C. Both gases diffuse from blood into alveoli
- D. Both gases diffuse from alveoli into blood
Explanation
The alveoli in the lungs are tiny sacs where the exchange of gases occurs. Oxygen from the inhaled air passes through the alveolar membrane into the blood in the capillaries, while carbon dioxide, a waste product of cellular metabolism, moves from the blood into the alveoli, where it is then exhaled.
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