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Free Gaseous Exchange in Lungs MCQs with Answers

47 Gaseous Exchange in Lungs MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Gaseous exchange in the lungs occurs across the thin, moist alveolar and capillary surfaces, where oxygen and carbon dioxide diffuse down partial pressure gradients. The topic covers alveolar adaptations, ventilation, the role of haemoglobin in oxygen transport, carbon dioxide carriage, and the difference between external gas exchange and cellular respiration.

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47 questions · page 3 of 3

41. The method of bringing oxygenated air into contact with a gas exchange surface is called ?

  • A. Photorespiration
  • B. Ventilation
  • C. Gaseous transport
  • D. Respiration

Explanation: Ventilation is the process of moving air in and out of the respiratory system, allowing for the exchange of gases (such as oxygen and…

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Correct answer: Ventilation

42. About 70% of the carbon dioxide is carried in blood as:

  • A. Carbonate
  • B. Bicarbonate
  • C. Tricarbonate
  • D. Carbonic anhydrase

Explanation: About 70 percent of CO2 is transported in the form of Bicarbonate ions.

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Correct answer: Bicarbonate

43. Which of the following ions play important role in the transportation of carbon dioxide?

  • A. Sodium
  • B. Potassium
  • C. Bicarbonate
  • D. Chloride

Explanation: The majority of carbon dioxide is transported as bicarbonate ions. This is because erythrocytes have a high activity of carbonic…

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Correct answer: Bicarbonate

44. Of 100 ml of arterial blood, oxygen provided to the tissues is:

  • A. 2ml
  • B. 3ml
  • C. 4ml
  • D. 5ml

Explanation: 6 mL of oxygen is delivered, at tissue level in normal conditions so option D is correct

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Correct answer: 5ml

45. The alveoli represent total surface area of

  • A. 10-30m
  • B. 30-60m
  • C. 70-90m
  • D. 90-110m

Explanation: The alveoli form the gas exchange surface in the lungs, with about 700 million alveoli contributing to a total surface area of 70-90m2.

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Correct answer: 70-90m

46. The alveoli is lined by:

  • A. Cuboidal epithelium
  • B. Squamous epithelium
  • C. Columnar epithelium
  • D. Transitional epithelium

Explanation: The alveoli, which are tiny air sacs in the lungs, are lined by a type of epithelium called squamous epithelium.

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Correct answer: Squamous epithelium

47. Which of the following statements Is not correct about alveoli:

  • A. Alveoli form the gas exchange surface
  • B. The wall of each alveolus is 0.1 cm thick
  • C. Alveoli has a dense network of capillaries
  • D. Collagen and elastin present in alveoli allow it to expand and recoil easily during breathing

Explanation: Option B regarding alveoli is not correct.The walls of alveoli are extremely thin, only about 0.0002 cm thick.

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Correct answer: The wall of each alveolus is 0.1 cm thick
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