NEET-UG Biology · Class 11
Gas exchange across the alveolar wall — NEET & JEE Questions
Gas exchange across the alveolar wall is a topic in Breathing and Exchange of Gases, a Class 11 Biology chapter of the NEET-UG syllabus. TestBudy holds 13 published NEET-UG questions on Gas exchange across the alveolar wall, each with the marking scheme of the real paper. The ideas it examines include Oxygen and carbon dioxide pressures at each site, The three layers gases cross in the alveolus, Why carbon dioxide crosses faster than oxygen.
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Key formulas and concepts
The ideas Gas exchange across the alveolar wall is examined on, as they are tagged in the syllabus tree.
- Oxygen and carbon dioxide pressures at each site
- The three layers gases cross in the alveolus
- Why carbon dioxide crosses faster than oxygen
Gas exchange across the alveolar wall MCQs with solutions
10 of the 13 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
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
By what main process do oxygen and carbon dioxide cross the alveolar membrane?
- A. Endocytosis
- B. Active transport
- C. Simple diffusion
- D. Facilitated pumping
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
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
Oxygen and carbon dioxide cross the alveolar-capillary membrane mainly by
- A. simple diffusion down partial-pressure gradients
- B. active transport using ATP
- C. endocytosis
- D. osmosis
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
Alveolar oxygen partial pressure is higher than that in deoxygenated pulmonary capillary blood. Oxygen therefore diffuses
- A. from alveoli into blood
- B. from blood into alveoli
- C. equally in both directions with no net movement
- D. only into pleural fluid
Pulmonary capillary carbon dioxide partial pressure exceeds alveolar carbon dioxide partial pressure. The net movement of CO2 is
- A. from blood to alveoli
- B. from alveoli to blood
- C. from blood to pleural cavity only
- D. zero
Why does a very thin alveolar-capillary barrier favour rapid gas exchange?
- A. Diffusion rate increases as diffusion distance decreases
- B. A thicker barrier creates a larger partial-pressure gradient automatically
- C. Thin membranes actively pump gases
- D. Barrier thickness does not affect diffusion
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
Common mistakes in Gas exchange across the alveolar wall
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Assumes only partial pressure, not membrane thickness, influences diffusion.
- Assumes fewer alveolar walls improve exchange by creating larger air spaces.
- Focuses on only one structural determinant of diffusion.
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