Human Physiology – Breathing and Exchange of Gases Quiz - ICSE Class 11 Biology

Free practice quiz: Human Physiology – Breathing and Exchange of Gases (ICSE Class 11 Biology). 52 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 11 Biology practice quiz has 52 multiple-choice questions on Human Physiology – Breathing and Exchange of Gases, and 52 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. Which of the following anatomical structures is primarily responsible for the efficient diffusion of gases between the alveoli and the pulmonary capillaries?

   1. The smooth muscle layer in the bronchioles
   2. The squamous epithelial cells forming the alveolar wall
   3. The elastic fibers surrounding the alveoli
   4. The goblet cells lining the trachea
   Show answer

   Answer: B. The squamous epithelial cells forming the alveolar wall

   The alveolar wall is extremely thin, composed of a single layer of squamous epithelial cells (type I pneumocytes), which minimizes the diffusion distance for oxygen and carbon dioxide between the alveolar air and the blood in the pulmonary capillaries. This thinness is crucial for efficient gas exchange.

2. What is the approximate percentage of oxygen transported in the blood bound to hemoglobin?

   1. 1.5%
   2. 3%
   3. 7%
   4. 98.5%
   Show answer

   Answer: D. 98.5%

   Oxygen is transported in the blood in two main ways: dissolved in the plasma (about 1.5%) and bound to hemoglobin within red blood cells (about 98.5%).

3. What effect does a decrease in atmospheric pressure at high altitudes have on the partial pressure of oxygen in the alveoli?

   1. Increases alveolar PO2
   2. Decreases alveolar PO2
   3. Has no effect on alveolar PO2
   4. Increases alveolar PCO2
   Show answer

   Answer: B. Decreases alveolar PO2

   At high altitudes, the total atmospheric pressure is lower. Although the percentage of oxygen in the air remains about 21%, the lower total pressure means that the partial pressure of oxygen (PO2) is also lower. This reduced alveolar PO2 is the primary challenge for gas exchange at high altitudes.

4. The vocal cords, which produce sound, are located in which part of the respiratory tract?

   1. Pharynx
   2. Trachea
   3. Larynx
   4. Bronchi
   Show answer

   Answer: C. Larynx

   The larynx, commonly known as the voice box, is situated between the pharynx and the trachea. It contains the vocal cords, which vibrate when air passes through them, producing sound.

5. Which nerve carries the primary motor signals from the respiratory center to the diaphragm?

   1. Vagus nerve
   2. Phrenic nerve
   3. Glossopharyngeal nerve
   4. Hypoglossal nerve
   Show answer

   Answer: B. Phrenic nerve

   The phrenic nerve originates from the cervical spinal cord (C3-C5) and innervates the diaphragm. It transmits motor impulses that cause the diaphragm to contract, initiating inspiration.

More questions in this quiz

Answers and explanations are in the full quiz.

1. During forced exhalation, which muscles, in addition to the diaphragm and external intercostals, are contracted to expel more air from the lungs?
2. What is the partial pressure of oxygen (PO2) in the arterial blood leaving the lungs, assuming normal physiological conditions?
3. The Bohr effect describes the influence of which factor on the oxygen-hemoglobin dissociation curve?
4. Which of the following is NOT a function of the conducting zone of the respiratory system?
5. The regulation of breathing rate is primarily controlled by respiratory centers located in which part of the brain?
6. What is the primary role of the surfactant produced by type II pneumocytes?
7. In which of the following locations is the partial pressure of carbon dioxide (PCO2) the highest?
8. The volume of air remaining in the lungs after a maximal exhalation is known as:
9. Which of the following is the most significant factor driving the diffusion of oxygen from the alveoli into the pulmonary capillaries?
10. The chemoreceptors that monitor changes in blood pH and PCO2 and play a crucial role in regulating breathing are primarily located in:
11. Which of the following statements accurately describes the process of CO2 transport in the blood?
12. What is the physiological significance of the Haldane effect?
13. During intense exercise, what is the most likely change in the partial pressure of oxygen (PO2) in the systemic arterial blood?
14. Which anatomical structure is the primary site for gas exchange in the human respiratory system?
15. The process of inspiration (inhalation) is primarily driven by:
16. What is the role of carbonic anhydrase in the red blood cells during carbon dioxide transport?
17. Which lung volume represents the maximal amount of air that can be exhaled after a normal tidal volume inhalation?
18. The neural stimulus for breathing originates from the:
19. The binding of oxygen to hemoglobin is a reversible process. What factor favors the release of oxygen from hemoglobin in the tissues?
20. Which component of the respiratory system is characterized by rings of hyaline cartilage that prevent its collapse?
21. What is the anatomical dead space?
22. The rate of diffusion of a gas across the respiratory membrane is directly proportional to which of the following?
23. In the lungs, the sympathetic nervous system generally causes:
24. Which of the following describes the function of the diaphragm during quiet inspiration?
25. What is the average resting tidal volume in an adult human?
26. The movement of oxygen from the alveoli into the pulmonary capillaries is driven by a difference in:
27. What is the primary stimulus for increasing the rate and depth of breathing during exercise?
28. Which structure is responsible for producing surfactant in the lungs?
29. When venous blood from the lungs passes through the pulmonary capillaries, it picks up oxygen and releases carbon dioxide. This gas exchange occurs due to:
30. What is the volume of air that can be forcibly exhaled after a normal exhalation?
31. Which of the following is a factor that DECREASES the affinity of hemoglobin for oxygen?
32. The rhythmic generation of the breathing impulse is primarily controlled by neurons in the:
33. What happens to the intrapleural pressure during inspiration?
34. Which of the following cells are primarily responsible for the phagocytosis of foreign particles and pathogens in the alveoli?
35. The oxygen-hemoglobin dissociation curve is S-shaped because:
36. Which of the following cartilaginous structures forms the majority of the anterior and lateral walls of the trachea?
37. When a person hyperventilates (breathes faster and deeper than normal), what is the most significant immediate effect on blood gas levels?
38. The term 'vital capacity' refers to:
39. Which of the following is NOT a characteristic of the respiratory membrane (alveolocapillary membrane)?
40. What is the primary mechanism by which the body eliminates excess carbon dioxide?
41. The 'respiratory zone' of the respiratory system is characterized by the presence of:
42. In the tissues, the conversion of carbonic acid back into carbon dioxide and water, facilitating CO2 release from the blood, is catalyzed by:
43. What is the approximate partial pressure of oxygen in the venous blood returning to the lungs?
44. The rhythmic control of breathing is most influenced by the concentration of which ion in the cerebrospinal fluid?
45. During expiration, what happens to the volume of the thoracic cavity?
46. Which type of cells in the alveoli are thin, flattened, and form the primary barrier for gas exchange?
47. The transport of bicarbonate ions out of red blood cells into the plasma in exchange for chloride ions is known as the:

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