NCERT NEET Biology English Medium Part-1 | Chapter 14 : Breathing and Exchange of Gases.

NCERT NEET Biology English Medium Part-1 | Chapter 14 : Breathing and Exchange of Gases.

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Question 1. Which of the following groups of animals primarily utilise simple diffusion over their entire body surface for gaseous exchange?

1. Sponges, coelenterates, and flatworms.
2. Earthworms, insects, and molluscs.
3. Sponges, roundworms, and terrestrial arthropods.
4. Flatworms, coelenterates, and aquatic arthropods.

Answer: a. Sponges, coelenterates, and flatworms.

Question 2. The moist cuticle is the primary respiratory surface for which of the following organisms?

1. Insects.
2. Earthworms.
3. Aquatic molluscs.
4. Frogs during pulmonary respiration.

Answer: b. Earthworms.

Question 3. Tracheal tubes are a specialized network used for transporting atmospheric air within the body in which organisms?

1. Terrestrial flatworms.
2. Aquatic arthropods.
3. Insects.
4. Amphibians.

Answer: c. Insects.

Question 4. Branchial respiration through special vascularised structures called gills is prominently seen in which groups?

1. Most aquatic arthropods and molluscs.
2. All terrestrial vertebrates.
3. Adult amphibians.
4. Insects and earthworms.

Answer: a. Most aquatic arthropods and molluscs.

Question 5. Among vertebrates, which classes exclusively or primarily respire through lungs?

1. Fishes, amphibians, and reptiles.
2. Amphibians, reptiles, birds, and mammals.
3. Reptiles, birds, and mammals.
4. Fishes and amphibians.

Answer: b. Amphibians, reptiles, birds, and mammals.

Question 6. Amphibians like frogs possess the unique ability to exchange gases through which of the following secondary pathways?

1. Tracheal tubes.
2. Moist skin.
3. Book lungs.
4. Gills in adulthood.

Answer: b. Moist skin.

Question 7. The nasal chamber opens into which of the following structures that serves as a common passage for food and air?

1. Larynx.
2. Pharynx.
3. Trachea.
4. Glottis.

Answer: b. Pharynx.

Question 8. The cartilaginous box that aids in sound production and connects the pharynx to the trachea is known as?

1. Glottis.
2. Epiglottis.
3. Larynx.
4. Bronchi.

Answer: c. Larynx.

Question 9. What is the function of the epiglottis during the swallowing of food?

1. It covers the pharynx to prevent air entry.
2. It covers the glottis to prevent food entry into the larynx.
3. It opens the trachea for continuous breathing.
4. It assists in vocalization during swallowing.

Answer: b. It covers the glottis to prevent food entry into the larynx.

Question 10. At which vertebral level does the trachea divide into the right and left primary bronchi?

1. 5th cervical vertebra.
2. 7th cervical vertebra.
3. 5th thoracic vertebra.
4. 12th thoracic vertebra.

Answer: c. 5th thoracic vertebra.

Question 11. Which parts of the respiratory tract are supported by incomplete cartilaginous rings?

1. Trachea, primary bronchi, and alveoli.
2. Trachea, primary, secondary, tertiary bronchi, and initial bronchioles.
3. Terminal bronchioles and alveoli.
4. Pharynx, larynx, and trachea.

Answer: b. Trachea, primary, secondary, tertiary bronchi, and initial bronchioles.

Question 12. The terminal bronchioles give rise to vascularised, bag-like structures called?

1. Primary bronchi.
2. Secondary bronchi.
3. Alveoli.
4. Pleura.

Answer: c. Alveoli.

Question 13. The lungs are covered by a double-layered membrane. What is it called?

1. Pericardium.
2. Peritoneum.
3. Pleura.
4. Meninges.

Answer: c. Pleura.

Question 14. What is the primary function of the pleural fluid present between the two pleural membranes?

1. To facilitate diffusion of oxygen.
2. To reduce friction on the lung surface.
3. To keep the alveoli continuously open.
4. To transport carbon dioxide to the blood.

Answer: b. To reduce friction on the lung surface.

Question 15. The outer pleural membrane is in close anatomical contact with which structure?

1. The lung surface.
2. The diaphragm only.
3. The thoracic lining.
4. The heart.

Answer: c. The thoracic lining.

Question 16. The conducting part of the human respiratory system extends from the external nostrils up to the?

1. Primary bronchi.
2. Alveolar ducts.
3. Terminal bronchioles.
4. Alveoli.

Answer: c. Terminal bronchioles.

Question 17. Which of the following is NOT a function of the conducting part of the respiratory system?

1. Clears incoming air of foreign particles.
2. Humidifies the atmospheric air.
3. Brings the air to body temperature.
4. Site of actual diffusion of oxygen and carbon dioxide.

Answer: d. Site of actual diffusion of oxygen and carbon dioxide.

Question 18. The respiratory or exchange part of the respiratory system is formed by which structures?

1. Trachea and primary bronchi.
2. Alveoli and their ducts.
3. Terminal bronchioles and initial bronchioles.
4. Larynx and pharynx.

Answer: b. Alveoli and their ducts.

Question 19. The thoracic chamber is formed ventrally by which bone?

1. Vertebral column.
2. Ribs.
3. Sternum.
4. Clavicle.

Answer: c. Sternum.

Question 20. The anatomical setup of lungs in the thorax is designed such that any change in the volume of the thoracic cavity reflects in the?

1. Pleural cavity.
2. Pericardial cavity.
3. Pulmonary cavity.
4. Abdominal cavity.

Answer: c. Pulmonary cavity.

Question 21. Breathing is primarily carried out by creating a pressure gradient between the lungs and the?

1. Blood vessels.
2. Atmosphere.
3. Heart.
4. Diaphragm.

Answer: b. Atmosphere.

Question 22. Inspiration occurs when the intra-pulmonary pressure is?

1. Equal to the atmospheric pressure.
2. Less than the atmospheric pressure.
3. Higher than the atmospheric pressure.
4. Fluctuating randomly.

Answer: b. Less than the atmospheric pressure.

Question 23. Contraction of the diaphragm increases the volume of the thoracic chamber in which axis?

1. Dorso-ventral axis.
2. Antero-posterior axis.
3. Lateral axis.
4. Transverse axis.

Answer: b. Antero-posterior axis.

Question 24. Contraction of external inter-costal muscles lifts the ribs and sternum, increasing the thoracic volume in which axis?

1. Dorso-ventral axis.
2. Antero-posterior axis.
3. Lateral axis.
4. Sagittal axis.

Answer: a. Dorso-ventral axis.

Question 25. An overall increase in thoracic volume leads to a decrease in intra-pulmonary pressure. This specific event directly results in?

1. Expiration.
2. Inspiration.
3. Cellular respiration.
4. Relaxation of the diaphragm.

Answer: b. Inspiration.

Question 26. Expiration is initiated by the relaxation of the diaphragm and which other muscle group?

1. External inter-costal muscles.
2. Abdominal muscles.
3. Internal inter-costal muscles.
4. Sternocleidomastoid muscles.

Answer: a. External inter-costal muscles.

Question 27. Normal breathing rate for a healthy human adult is approximately?

1. 70-72 times per minute.
2. 12-16 times per minute.
3. 20-25 times per minute.
4. 8-10 times per minute.

Answer: b. 12-16 times per minute.

Question 28. Which instrument is used for clinical assessment of pulmonary functions by estimating the volume of air involved in breathing?

1. Sphygmomanometer.
2. Electrocardiograph.
3. Spirometer.
4. Stethoscope.

Answer: c. Spirometer.

Question 29. The volume of air inspired or expired during a normal respiration is defined as?

1. Tidal Volume.
2. Inspiratory Reserve Volume.
3. Expiratory Reserve Volume.
4. Residual Volume.

Answer: a. Tidal Volume.

Question 30. What is the approximate value of Tidal Volume (TV) for a healthy man?

1. 1000 mL.
2. 500 mL.
3. 2500 mL.
4. 1200 mL.

Answer: b. 500 mL.

Question 31. The additional volume of air a person can inspire by a forcible inspiration is termed as?

1. Tidal Volume.
2. Inspiratory Capacity.
3. Inspiratory Reserve Volume.
4. Vital Capacity.

Answer: c. Inspiratory Reserve Volume.

Question 32. The average value of Inspiratory Reserve Volume (IRV) is?

1. 1000 mL to 1100 mL.
2. 500 mL to 1000 mL.
3. 1100 mL to 1200 mL.
4. 2500 mL to 3000 mL.

Answer: d. 2500 mL to 3000 mL.

Question 33. The additional volume of air a person can expire by a forcible expiration is known as?

1. Residual Volume.
2. Expiratory Reserve Volume.
3. Tidal Volume.
4. Expiratory Capacity.

Answer: b. Expiratory Reserve Volume.

Question 34. What is the normal average value of Expiratory Reserve Volume (ERV)?

1. 500 mL to 800 mL.
2. 2500 mL to 3000 mL.
3. 1000 mL to 1100 mL.
4. 1100 mL to 1200 mL.

Answer: c. 1000 mL to 1100 mL.

Question 35. The volume of air remaining in the lungs even after a forcible expiration is defined as?

1. Functional Residual Capacity.
2. Expiratory Reserve Volume.
3. Residual Volume.
4. Vital Capacity.

Answer: c. Residual Volume.

Question 36. What is the typical value of Residual Volume (RV) in humans?

1. 500 mL to 1000 mL.
2. 1000 mL to 1100 mL.
3. 1100 mL to 1200 mL.
4. 2500 mL to 3000 mL.

Answer: c. 1100 mL to 1200 mL.

Question 37. The total volume of air a person can inspire after a normal expiration is called Inspiratory Capacity. It is mathematically equal to?

1. TV + ERV.
2. TV + IRV.
3. ERV + RV.
4. TV + IRV + ERV.

Answer: b. TV + IRV.

Question 38. Expiratory Capacity (EC) is the total volume of air a person can expire after a normal inspiration. It includes?

1. TV + ERV.
2. ERV + RV.
3. TV + IRV.
4. IRV + ERV.

Answer: a. TV + ERV.

Question 39. Functional Residual Capacity (FRC) represents the air left in lungs after normal expiration and is equal to?

1. ERV + RV.
2. TV + ERV.
3. IRV + RV.
4. TV + IRV.

Answer: a. ERV + RV.

Question 40. The maximum volume of air a person can breathe in after a forced expiration is defined as?

1. Total Lung Capacity.
2. Functional Residual Capacity.
3. Vital Capacity.
4. Inspiratory Capacity.

Answer: c. Vital Capacity.

Question 41. Vital Capacity (VC) is the sum of which of the following respiratory volumes?

1. TV + IRV + RV.
2. ERV + TV + IRV.
3. ERV + RV.
4. TV + ERV + RV.

Answer: b. ERV + TV + IRV.

Question 42. Total Lung Capacity (TLC) encompasses the maximum volume of air accommodated in lungs and equals?

1. VC + RV.
2. VC + ERV.
3. IRV + ERV.
4. FRC + TV.

Answer: a. VC + RV.

Question 43. The primary sites for the exchange of gases in the human body are the?

1. Primary bronchi.
2. Tracheae.
3. Alveoli.
4. Terminal bronchioles.

Answer: c. Alveoli.

Question 44. The exchange of oxygen and carbon dioxide in the alveoli occurs primarily by?

1. Active transport.
2. Simple diffusion based on pressure/concentration gradient.
3. Facilitated diffusion via carrier proteins.
4. Osmosis.

Answer: b. Simple diffusion based on pressure/concentration gradient.

Question 45. The pressure contributed by an individual gas in a mixture of gases is referred to as?

1. Osmotic pressure.
2. Absolute pressure.
3. Partial pressure.
4. Total atmospheric pressure.

Answer: c. Partial pressure.

Question 46. What is the partial pressure of oxygen (pO2) in atmospheric air?

1. 104 mm Hg.
2. 159 mm Hg.
3. 40 mm Hg.
4. 95 mm Hg.

Answer: b. 159 mm Hg.

Question 47. What is the partial pressure of oxygen (pO2) in the alveoli?

1. 159 mm Hg.
2. 104 mm Hg.
3. 95 mm Hg.
4. 40 mm Hg.

Answer: b. 104 mm Hg.

Question 48. What is the partial pressure of carbon dioxide (pCO2) in deoxygenated blood?

1. 40 mm Hg.
2. 45 mm Hg.
3. 104 mm Hg.
4. 0.3 mm Hg.

Answer: b. 45 mm Hg.

Question 49. What is the partial pressure of oxygen (pO2) in oxygenated blood?

1. 104 mm Hg.
2. 95 mm Hg.
3. 40 mm Hg.
4. 45 mm Hg.

Answer: b. 95 mm Hg.

Question 50. The partial pressure of carbon dioxide (pCO2) in the tissues is?

1. 40 mm Hg.
2. 45 mm Hg.
3. 104 mm Hg.
4. 95 mm Hg.

Answer: b. 45 mm Hg.

Question 51. The solubility of carbon dioxide compared to oxygen is approximately?

1. 2-5 times higher.
2. 20-25 times higher.
3. 10-15 times higher.
4. 20-25 times lower.

Answer: b. 20-25 times higher.

Question 52. Due to its higher solubility, the amount of CO2 that can diffuse through the membrane per unit partial pressure difference is?

2. Much lower compared to O2.
3. Much higher compared to O2.
4. Exactly equal to O2.
5. Negligible.

Answer: b. Much higher compared to O2.

Question 53. The diffusion membrane consists of how many major layers?

1. Two.
2. Three.
3. Four.
4. Five.

Answer: b. Three.

Question 54. Which of the following is NOT a constituent layer of the diffusion membrane?

1. Thin squamous epithelium of alveoli.
2. Endothelium of alveolar capillaries.
3. Basement substance between the layers.
4. Columnar epithelium of terminal bronchioles.

Answer: d. Columnar epithelium of terminal bronchioles.

Question 55. The total thickness of the diffusion membrane in humans is?

1. Exactly one millimetre.
2. More than a centimetre.
3. Much less than a millimetre.
4. Two millimetres.

Answer: c. Much less than a millimetre.

Question 56. What percentage of oxygen is transported by RBCs in the blood?

1. 70 per cent.
2. 97 per cent.
3. 20-25 per cent.
4. 3 per cent.

Answer: b. 97 per cent.

Question 57. The remaining 3 per cent of oxygen is carried in what form?

1. As bicarbonate in plasma.
2. Bound to plasma proteins.
3. In a dissolved state through the plasma.
4. By white blood cells.

Answer: c. In a dissolved state through the plasma.

Question 58. Nearly 70 per cent of carbon dioxide is transported in the blood as?

1. Carbamino-haemoglobin.
2. Dissolved gas in plasma.
3. Bicarbonate.
4. Carboxyhaemoglobin.

Answer: c. Bicarbonate.

Question 59. What percentage of carbon dioxide is transported by RBCs as carbamino-haemoglobin?

1. 7 per cent.
2. 70 per cent.
3. 20-25 per cent.
4. 97 per cent.

Answer: c. 20-25 per cent.

Question 60. Haemoglobin is a red coloured pigment that primarily contains which element?

1. Copper.
2. Iron.
3. Magnesium.
4. Calcium.

Answer: b. Iron.

Question 61. Each haemoglobin molecule can carry a maximum of how many molecules of oxygen?

1. Two.
2. Three.
3. Four.
4. Six.

Answer: c. Four.

Question 62. The binding of oxygen with haemoglobin is primarily dependent upon which factor?

2. Partial pressure of CO2.
3. Partial pressure of O2.
4. Hydrogen ion concentration.
5. Body temperature.

Answer: b. Partial pressure of O2.

Question 63. When the percentage saturation of haemoglobin with O2 is plotted against the pO2, the resulting curve is?

1. Hyperbolic curve.
2. Linear curve.
3. Sigmoid curve.
4. Parabolic curve.

Answer: c. Sigmoid curve.

Question 64. In the alveoli, which of the following conditions favors the formation of oxyhaemoglobin?

1. High pO2, low pCO2, lesser H+ concentration, lower temperature.
2. Low pO2, high pCO2, higher H+ concentration, higher temperature.
3. High pO2, high pCO2, lesser H+ concentration, lower temperature.
4. High pO2, low pCO2, higher H+ concentration, higher temperature.

Answer: a. High pO2, low pCO2, lesser H+ concentration, lower temperature.

Question 65. In the tissues, which set of conditions favors the dissociation of oxygen from oxyhaemoglobin?

1. High pO2, low pCO2, lesser H+ concentration, lower temperature.
2. Low pO2, high pCO2, high H+ concentration, higher temperature.
3. Low pO2, low pCO2, high H+ concentration, higher temperature.
4. High pO2, high pCO2, low H+ concentration, lower temperature.

Answer: b. Low pO2, high pCO2, high H+ concentration, higher temperature.

Question 66. 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.

Answer: b. 5 ml.

Question 67. CO2 is carried by haemoglobin in the RBCs as which complex?

1. Carboxyhaemoglobin.
2. Carbamino-haemoglobin.
3. Bicarbonate-haemoglobin.
4. Oxyhaemoglobin.

Answer: b. Carbamino-haemoglobin.

Question 68. The binding of CO2 to haemoglobin is highly influenced by the partial pressure of which gas?

1. Nitrogen.
2. Oxygen.
3. Carbon monoxide.
4. Helium.

Answer: b. Oxygen.

Question 69. When pCO2 is high and pO2 is low in the tissues, what happens to the binding of carbon dioxide?

1. Less binding of carbon dioxide occurs.
2. More binding of carbon dioxide occurs.
3. Carbon dioxide binding stops entirely.
4. Oxygen tightly binds to haemoglobin.

Answer: b. More binding of carbon dioxide occurs.

Question 70. The enzyme that catalyzes the reaction between CO2 and water to form carbonic acid is?

1. Carbonic anhydrase.
2. Carboxylase.
3. Dehydrogenase.
4. Oxygenase.

Answer: a. Carbonic anhydrase.

Question 71. Carbonic anhydrase is present in a very high concentration in the?

1. Blood plasma.
2. White blood cells.
3. Red blood cells.
4. Platelets.

Answer: c. Red blood cells.

Question 72. In the tissues where pCO2 is high due to catabolism, CO2 diffuses into blood and forms?

1. Only dissolved CO2 gas.
2. HCO3- and H+.
3. Pure carbonic acid that remains stable.
4. Carboxyhaemoglobin exclusively.

Answer: b. HCO3- and H+.

Question 73. At the alveolar site where pCO2 is low, the reaction catalyzed by carbonic anhydrase proceeds in the opposite direction leading to the formation of?

1. CO2 and H2O.
2. HCO3- and H+.
3. Carbon monoxide.
4. Bicarbonate ions solely.

Answer: a. CO2 and H2O.

Question 74. Every 100 ml of deoxygenated blood delivers approximately how much CO2 to the alveoli?

1. 5 ml.
2. 4 ml.
3. 10 ml.
4. 20 ml.

Answer: b. 4 ml.

Question 75. The primary centre responsible for the regulation of the respiratory rhythm is located in which region of the brain?

1. Cerebrum.
2. Cerebellum.
3. Medulla region.
4. Hypothalamus.

Answer: c. Medulla region.

Question 76. The pneumotaxic centre, which can moderate the functions of the respiratory rhythm centre, is present in the?

1. Medulla oblongata.
2. Pons region of the brain.
3. Cerebrum.
4. Diencephalon.

Answer: b. Pons region of the brain.

Question 77. A neural signal from the pneumotaxic centre can alter the respiratory rate primarily by?

1. Increasing the duration of expiration.
2. Reducing the duration of inspiration.
3. Completely stopping the respiratory rhythm.
4. Increasing the duration of inspiration.

Answer: b. Reducing the duration of inspiration.

Question 78. A chemosensitive area situated adjacent to the rhythm centre is highly sensitive to increases in?

1. CO2 and hydrogen ions.
2. Oxygen and bicarbonate.
3. Nitrogen and oxygen.
4. Oxygen and hydrogen ions.

Answer: a. CO2 and hydrogen ions.

Question 79. Receptors associated with which structures can recognise changes in CO2 and H+ concentration and signal the rhythm centre?

1. Pulmonary artery and vein.
2. Aortic arch and carotid artery.
3. Vena cava and aorta.
4. Coronary artery and carotid artery.

Answer: b. Aortic arch and carotid artery.

Question 80. The role of which gas is considered quite insignificant in the direct regulation of the respiratory rhythm?

1. Carbon dioxide.
2. Nitrogen.
3. Oxygen.
4. Carbon monoxide.

Answer: c. Oxygen.

Question 81. Asthma is defined as a difficulty in breathing causing wheezing. This is primarily due to the?

1. Damage to the alveolar walls.
2. Inflammation of bronchi and bronchioles.
3. Proliferation of fibrous tissues.
4. Reduced production of surfactant.

Answer: b. Inflammation of bronchi and bronchioles.

Question 82. Emphysema is a chronic respiratory disorder mainly characterized by?

1. Inflammation of the pleura.
2. Damage to alveolar walls leading to decreased respiratory surface.
3. Blockage of the trachea.
4. Excessive fluid accumulation in lungs.

Answer: b. Damage to alveolar walls leading to decreased respiratory surface.

Question 83. Which lifestyle habit is identified as one of the major causes of emphysema?

1. High sugar diet.
2. Lack of exercise.
3. Cigarette smoking.
4. Alcohol consumption.

Answer: c. Cigarette smoking.

Question 84. Occupational respiratory disorders are frequently caused by long-term exposure to dust in industries such as stone-breaking, which leads to?

1. Immediate asthma attack.
2. Proliferation of fibrous tissues (fibrosis).
3. Decreased red blood cell count.
4. Increase in vital capacity.

Answer: b. Proliferation of fibrous tissues (fibrosis).

Question 85. To calculate Functional Residual Capacity (FRC), which two respiratory volumes must be added?

1. Tidal Volume and Inspiratory Reserve Volume.
2. Expiratory Reserve Volume and Residual Volume.
3. Vital Capacity and Residual Volume.
4. Tidal Volume and Expiratory Reserve Volume.

Answer: b. Expiratory Reserve Volume and Residual Volume.

Question 86. Which anatomical setup prevents the collapse of the initial bronchioles and trachea?

1. Complete bony rings.
2. Smooth muscle bands.
3. Incomplete cartilaginous rings.
4. Elastic connective tissue.

Answer: c. Incomplete cartilaginous rings.

Question 87. If a person forcefully exhales maximally, the volume of air left inside their lungs is the?

1. Tidal Volume.
2. Expiratory Reserve Volume.
3. Vital Capacity.
4. Residual Volume.

Answer: d. Residual Volume.

Question 88. Consider an individual taking a deep breath after forcefully expiring all possible air. The total volume of air inspired represents their?

1. Inspiratory Capacity.
2. Vital Capacity.
3. Total Lung Capacity.
4. Functional Residual Capacity.

Answer: b. Vital Capacity.

Question 89. In a mixture of gases, oxygen diffuses from alveoli to blood because?

1. pO2 in alveoli is 40 mm Hg and in blood is 104 mm Hg.
2. pO2 in alveoli is 104 mm Hg and in deoxygenated blood is 40 mm Hg.
3. pO2 in alveoli is 95 mm Hg and in deoxygenated blood is 40 mm Hg.
4. pO2 in alveoli is 45 mm Hg and in deoxygenated blood is 40 mm Hg.

Answer: b. pO2 in alveoli is 104 mm Hg and in deoxygenated blood is 40 mm Hg.

Question 90. Which structural feature of the alveoli facilitates rapid gas exchange?

1. Thick stratified squamous epithelium.
2. Thin squamous epithelium.
3. Columnar ciliated epithelium.
4. Cuboidal epithelium.

Answer: b. Thin squamous epithelium.

Question 91. The basement substance in the diffusion membrane is composed of a thin basement membrane supporting the alveolar epithelium and the?

1. Smooth muscle layer.
2. Basement membrane surrounding the endothelial cells of capillaries.
3. Cartilaginous layer.
4. Pleural membrane.

Answer: b. Basement membrane surrounding the endothelial cells of capillaries.

Question 92. The saturation of haemoglobin with oxygen significantly decreases when the?

1. pCO2 decreases.
2. Temperature decreases.
3. H+ concentration increases.
4. pH increases.

Answer: c. H+ concentration increases.

Question 93. A rightward shift of the oxygen dissociation curve indicates?

1. Increased affinity of haemoglobin for oxygen.
2. Decreased affinity of haemoglobin for oxygen.
3. No change in affinity.
4. Increased formation of oxyhaemoglobin.

Answer: b. Decreased affinity of haemoglobin for oxygen.

Question 94. The continuous demand for oxygen and production of carbon dioxide by the tissues is driven by which cellular process?

1. Photosynthesis.
2. Catabolic reactions.
3. Anabolic reactions.
4. Active transport.

Answer: b. Catabolic reactions.

Question 95. The double-layered pleura and pleural fluid primarily serve to?

1. Enhance oxygen absorption.
2. Regulate intrapulmonary pressure.
3. Reduce friction on the lung surface during breathing movements.
4. Provide structural support to incomplete cartilaginous rings.

Answer: c. Reduce friction on the lung surface during breathing movements.

Question 96. If a healthy human breathes 12 times a minute, what is their approximate minute ventilation (total volume of air inspired per minute)?

1. 1000 mL.
2. 6000 mL.
3. 12000 mL.
4. 500 mL.

Answer: b. 6000 mL.

Question 97. If a person’s ERV is 1000 mL, TV is 500 mL, and IRV is 3000 mL, what is their Vital Capacity?

1. 4000 mL.
2. 4500 mL.
3. 3500 mL.
4. 5000 mL.

Answer: b. 4500 mL.

Question 98. Which of the following is an INCORRECT match regarding gas transport?

1. O2 transport by RBCs: 97 per cent.
2. CO2 transport as bicarbonate: 70 per cent.
3. CO2 transport by RBCs: 20-25 per cent.
4. O2 transport dissolved in plasma: 10 per cent.

Answer: d. O2 transport dissolved in plasma: 10 per cent.

Question 99. The chemosensitive area adjacent to the rhythm centre is highly sensitive to changes in the concentration of?

1. pO2 only.
2. Glucose levels.
3. CO2 and hydrogen ions.
4. Sodium and potassium ions.

Answer: c. CO2 and hydrogen ions.

Question 100. During inspiration, what is the sequence of muscular contraction that increases the thoracic volume?

1. Contraction of internal intercostal muscles followed by relaxation of the diaphragm.
2. Contraction of the diaphragm and contraction of external intercostal muscles.
3. Relaxation of the diaphragm and contraction of external intercostal muscles.
4. Relaxation of the diaphragm and relaxation of external intercostal muscles.

Answer: b. Contraction of the diaphragm and contraction of external intercostal muscles.

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