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NEET-UG Biology

Gas exchange across the alveolar wall — practice questions

6 questions in the bank on this idea. Below are 6 of them, exactly as they appear in a test.

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  1. Question 1 · difficulty L1 · recall

    The main physical process responsible for gas exchange across the respiratory membrane:

    • A. active transport of oxygen
    • B. endocytosis
    • C. diffusion down partial-pressure gradients
    • D. osmosis of gases

  2. Question 2 · difficulty L1 · recall

    By what main process do oxygen and carbon dioxide cross the alveolar membrane?

    • A. Endocytosis
    • B. Active transport
    • C. Simple diffusion
    • D. Facilitated pumping

  3. Question 3 · difficulty L2 · understanding

    Why does oxygen diffuse from alveolar air into pulmonary blood?

    • A. Haemoglobin actively pumps oxygen across the alveolus
    • B. Blood has a higher oxygen partial pressure than alveolar air
    • C. Carbon dioxide pushes oxygen through the membrane
    • D. Alveolar partial pressure of oxygen is higher than that in deoxygenated blood

  4. Question 4 · difficulty L2 · understanding

    Alveolar air has a high oxygen partial pressure and low carbon dioxide partial pressure, while incoming pulmonary blood has the opposite pattern. What net gas movements should occur before the blood leaves the alveolar capillaries?

    • A. Both gases enter alveoli
    • B. Both gases enter blood
    • C. Oxygen enters blood and carbon dioxide enters alveoli
    • D. Oxygen enters alveoli and carbon dioxide enters blood

  5. Question 5 · difficulty L3 · application

    An alveolar membrane becomes abnormally thick while the oxygen partial-pressure gradient remains unchanged. What is the most likely effect?

    • A. Oxygen diffusion becomes slower
    • B. Oxygen diffusion becomes faster
    • C. Carbon dioxide production stops
    • D. Haemoglobin concentration automatically doubles

  6. Question 6 · difficulty L4 · analysis

    Carbon dioxide has a smaller partial-pressure gradient across the respiratory membrane than oxygen, yet it diffuses efficiently. Which property best explains this?

    • A. Carbon dioxide is actively transported
    • B. Carbon dioxide is much more soluble in the diffusion membrane than oxygen
    • C. Carbon dioxide has a much larger molecular size
    • D. Oxygen cannot dissolve in blood

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