Selected Qs - Breathing and Exchange of Gases - NCERT Exemplar Converted to MCQs

1. The volume of air remaining in lungs after a normal expiration is called:
1. Tidal Volume
2. Residual Volume
3. Vital Capacity
4. Functional Residual Capacity

2. The respiratory surface in human lungs is:
1. Bronchi
2. Bronchioles
3. Alveoli
4. Trachea

3. Maximum oxygen transport in blood occurs through:
1. Plasma
2. White blood cells
3. Hemoglobin in RBCs
4. Platelets

4. The partial pressure of oxygen in atmospheric air is approximately:
1. 159 mm Hg
2. 104 mm Hg
3. 40 mm Hg
4. 95 mm Hg

5. Tidal volume in a healthy person is approximately:
1. 2500 mL
2. 1100 mL
3. 500 mL
4. 1500 mL

6. In asthma, the difficulty in breathing is primarily due to:

1.	Damage to alveolar walls
2.	Inflammation and narrowing of bronchi and bronchioles
3.	Accumulation of fluid in the pleural cavity
4.	Paralysis of the diaphragm

7. The fluid-filled double membranous layer surrounding the lungs is called:
1. Pericardium
2. Peritoneum
3. Pleura
4. Meninges

8. The primary site for the exchange of gases in the human body is:
1. Bronchi
2. Bronchioles
3. Alveoli
4. Trachea

9. Cigarette smoking leads to emphysema because:

1.	Nicotine causes bronchospasm
2.	Tar deposits cause destruction of alveolar walls, reducing surface area for gas exchange
3.	Carbon monoxide binds irreversibly with haemoglobin
4.	Smoke paralyses the diaphragm

10. Under normal physiological conditions, every 100 mL of oxygenated blood delivers approximately how much O₂ to the tissues?
1. 4 mL
2. 5 mL
3. 10 mL
4. 20 mL

11. The 3% of O₂ that is not transported by haemoglobin is carried:
1. By leucocytes
2. As bicarbonate ions in plasma
3. In a dissolved state in plasma
4. Bound to carbonic anhydrase

12. Arrange the following in ascending order of their volumes: Tidal Volume (TV), Residual Volume (RV), Inspiratory Reserve Volume (IRV), Expiratory Capacity (EC)
1. TV < RV < IRV < EC
2. RV < TV < EC < IRV
3. TV < RV < EC < IRV
4. RV < TV < IRV < EC

13. Inspiratory Capacity (IC) is equal to:
1. TV + ERV
2. TV + IRV
3. ERV + RV
4. IRV + ERV

14. Expiratory Capacity (EC) is equal to:
1. TV + IRV
2. ERV + RV
3. TV + ERV
4. IRV + ERV

15. Functional Residual Capacity (FRC) is the sum of:
1. TV + RV
2. ERV + RV
3. IRV + TV
4. TV + ERV

16. The respiratory organ of a flatworm is:
1. Gills
2. Lungs
3. Tracheal system
4. Body surface (general body surface by diffusion)

17. Which of the following organisms uses both lungs and moist skin for respiration?
1. Cockroach
2. Earthworm
3. Frog
4. Fish

18. The respiratory organ in cockroach is:
1. Lungs
2. Gills
3. Moist body surface
4. Tracheal system

19. Which of the following plays the most important role in creating the pressure gradient for normal breathing?
1. Lungs
2. Diaphragm and external intercostal muscles
3. Ribs alone
4. Abdominal muscles

20. CO₂ is transported in the blood in three forms. Which of the following is NOT one of them?
1. As dissolved CO₂ in plasma (~7%)
2. As bicarbonate ions (~70%)
3. As carbaminohaemoglobin (~20–25%)
4. As carboxyhaemoglobin (~3%)

21. CO₂ diffuses through the alveolar membrane at a much higher rate than O₂ per unit difference in partial pressure because:

1.	CO₂ is lighter than O₂
2.	CO₂ has a higher partial pressure in the alveoli
3.	The solubility of CO₂ in blood is about 20–25 times higher than O₂
4.	The alveolar membrane is more permeable to CO₂ only at night

22. The correct sequence of steps in the process of respiration is:

1.	Pulmonary ventilation → Diffusion across alveolar membrane → Transport by blood → Diffusion between blood and tissues → Cellular utilisation
2.	Diffusion across alveolar membrane → Pulmonary ventilation → Transport by blood → Cellular utilisation → Diffusion between blood and tissues
3.	Transport by blood → Pulmonary ventilation → Diffusion across alveolar membrane →Diffusion between blood and tissues → Cellular utilisation
4.	Cellular utilisation → Transport by blood → Diffusion across alveolar membrane →Pulmonary ventilation → Diffusion between blood and tissues

23. Inspiratory Reserve Volume (IRV) is defined as:

1.	The volume of air remaining in the lungs after normal expiration
2.	The additional volume of air that can be inspired forcibly after normal inspiration
3.	The additional volume of air that can be expired forcibly after normal expiration
4.	The volume of air inspired or expired during normal breathing

24. Expiratory Reserve Volume (ERV) is:

1.	The volume of air breathed in during normal breathing
2.	The volume of air remaining after forced expiration
3.	The additional volume of air that can be forcefully exhaled after a normal expiration
4.	The total volume the lungs can hold

25. Vital Capacity (VC) differs from Total Lung Capacity (TLC) in that TLC includes:
1. Tidal volume
2. Inspiratory reserve volume
3. Expiratory reserve volume
4. Residual volume

26. Emphysema and occupational respiratory disorders (e.g., silicosis, asbestosis) differ mainly in that:

1.	Emphysema involves destruction of alveolar walls, while occupational disorders involve fibrosis of lung tissue due to chronic exposure to industrial pollutants
2.	Emphysema is caused by bacteria, while occupational disorders are viral
3.	Emphysema affects the trachea, while occupational disorders affect the bronchi
4.	There is no difference; both are the same disease

27. At the tissue level, O₂ dissociates from oxyhaemoglobin primarily because:
1. pO₂ is high and pCO₂ is low in tissues
2. pO₂ is low and pCO₂ is high in tissues
3. pH is high in tissues
4. Temperature is lower in tissues

28. At the alveolar level, CO₂ is released from the blood because:

1.	pCO₂ in the alveoli is higher than in the blood
2.	pCO₂ in the blood is higher than in the alveoli, and pO₂ is higher in the alveoli
3.	Haemoglobin has higher affinity for CO₂ at the alveoli
4.	Carbonic anhydrase is absent at the alveolar level

29. During inspiration, the diaphragm:

1.	Relaxes and becomes dome-shaped
2.	Contracts and flattens, increasing thoracic volume
3.	Contracts and decreases thoracic volume
4.	Has no role in breathing

30. During normal expiration:

1.	The diaphragm and external intercostal muscles contract
2.	The internal intercostal muscles contract actively
3.	The diaphragm and external intercostal muscles relax, decreasing thoracic volume
4.	The abdominal muscles contract forcefully

31. The pneumotaxic centre in the regulation of respiration is located in:
1. Medulla oblongata
2. Pons (of the brain stem)
3. Cerebellum
4. Hypothalamus

32. The chemosensitive area near the respiratory rhythm centre is highly sensitive to:
1. O₂ concentration in blood
2. CO₂ and H⁺ ion concentration in blood
3. N₂ concentration in blood
4. Haemoglobin levels in blood

33. Receptors associated with the aortic arch and carotid artery that detect changes in O₂ and CO₂ levels are called:
1. Baroreceptors
2. Proprioceptors
3. Chemoreceptors (peripheral)
4. Thermoreceptors

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