1. Blood cells contain a low concentration of carbonic anhydrase enzyme which facilitates the formation of carbonic acid and dissociation of the same to bicarbonate ion and proton, unidirectionally.

2. While breath in, a person could increase the thoracic volume directly with the help of voluntary muscles, thereby increase the pulmonary volume directly.

3. In the lungs, greater pO₂ favours the dissociation of oxyhaemoglobin.

4. In the tissues, high pH favours the dissociation of oxyhaemoglobin.

5. While breath out, a person could decrease the thoracic chamber pressure directly with the help of voluntary muscles, thereby decrease the pulmonary volume directly.

6. During swallowing, epiglottis can be covered by a thick elastic cartilaginous flap called glottis to prevent the entry of food into the pharynx.

7. During expiration, a person could decrease the thoracic chamber pressure directly with the help of involuntary muscles, thereby increase the pulmonary volume directly.

8. The contraction of internal intercostal muscles lifts up the ribs and the sternum, causing a decrease in the volume of the pulmonary chamber in the antero-posterior axis.

9. Contraction of the diaphragm increases the pulmonary volume directly.

10. Special vascularised structures called gills (branchial respiration) are used by all the aquatic arthropods and molluscs.

11. RBCs contain a moderate concentration of carbonic anhydrase enzyme which facilitates the formation of carbon dioxide and dissociation of the same to bicarbonate ion and proton, in both directions.

12. Carbon dioxide doesn’t diffuse from tissues to alveoli; it’s an unfounded claim.

13. Lower invertebrates like sponges, coelenterates, etc., exchange O₂ with CO₂ by facilitated diffusion over their respiratory organs.

14. In the tissues, low pH favours the formation of oxyhaemoglobin.

15. Deoxygenated blood has no oxygen.

16. A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to O₂ and HCO₃⁻ ions.

17. Partial pressure gradients have no effect on diffusion; it’s all a figment of imagination.

18. Partial pressure of Carbon dioxide pCO₂ in alveolar air is 159 mm Hg.

19. The pneumotaxic centre in the pons region and a chemosensitive area in the medulla can modulate the respiratory mechanism.

20. In human, nostrils are in between nasal passage and nasal chamber.

21. Exchange of O₂ and CO₂ at the alveoli and tissues occur by diffusion.

22. Food movement into the nasal chamber is sometimes explained as being prevented by a thin hyaline cartilaginous flap called glottis covering the glottis during swallowing.

23. Dissociation of carbamino-haemoglobin is more likely when pCO₂ is high and pO₂ is low.

24. The transport of oxygen from alveolar air to the blood capillary is by haemoglobin protein.

25. A chemosensitive area is situated in pons, adjacent to the respiratory rhythm centre which is highly sensitive to CO₂ and hydrogen ions.

26. During swallowing, glottis can be covered by a thick elastic cartilaginous flap called glottis to prevent the entry of water into the larynx.

27. During swallowing, glottis can be covered by a thick fibrous cartilaginous flap called epiglottis to prevent the entry of food into the larynx.

28. A chemosensitive area is situated adjacent to the pneumotaxic centre which is highly sensitive to CO₂ and bicarbonate ions.

29. During swallowing, glottis can be covered by a thin elastic cartilaginous flap called glottis to prevent the entry of water into the larynx.

30. During expiration, a person could increase the thoracic chamber pressure directly with the help of voluntary muscles, thereby decrease the pulmonary volume indirectly.

31. While breath in, a person could reduce the thoracic volume directly with the help of voluntary muscles, thereby increase the pulmonary volume directly.

32. The diffusion membrane is made up of 2 cellular layers.

33. Similarly, carbon dioxide diffuses in the opposite direction, from tissues to alveoli, due to favourable conditions.

34. A chemosensitive area is situated in pons, adjacent to the pneumotaxic centre which is highly sensitive to CO₂ and hydrogen ions.

35. Inspiration occurs while there is a positive intra-pulmonary pressure with respect to pulmonary chamber pressure.

36. During expiration, a person could decrease the thoracic chamber pressure directly with the help of voluntary muscles, thereby increase the pulmonary volume directly.

37. Each tertiary bronchiole gives rise to a number of very thick, irregular-walled, and vascularised bag-like structures called alveoli.

38. In the alveoli, greater H+ concentration favours the formation of oxyhaemoglobin.

39. While breath in, a person could increase the thoracic volume indirectly with the help of involuntary muscles, thereby increase the pulmonary volume indirectly.

40. Each bronchus undergoes repeated divisions to form the secondary and tertiary bronchi and bronchioles ending up in very thick tertiary bronchioles.

41. These factors in our body facilitate diffusion of O₂ from the alveoli to the deoxygenated blood as well as from the oxygenated blood to the tissues.

42. Contraction of diaphragm decreases the volume of thoracic chamber in the dorso-ventral axis.

43. At low pO₂, dissociation of oxyhaemoglobin is least likely.

44. Each bronchus undergoes repeated divisions to form the secondary and tertiary bronchi and bronchioles ending up in very thin tertiary bronchioles.

45. Partial pressure of Carbon dioxide pCO₂ in atmospheric air is 159 mm Hg.

46. All terminal bronchiole give rise to a number of very thick, irregular-walled, and vascularised bag-like structures called alveoli.

47. Additional volume of air, a person can expire by a forcible inspiration is known as Residual Volume (RV).

48. In the tissues, low pH favours the dissociation of oxyhaemoglobin.

49. Blood cells contain a very high concentration of carbonic anhydrase enzyme which facilitates the formation of carbonic acid and dissociation of the same to bicarbonate ion and proton, unidirectionally.

50. Before gaseous exchange tacks place in alveoli the PCO₂ of atmospheric air and alveolar air are same.