Breathing and Exchange of Gases Mock Test – Class 11 Biology

1. Airway observations are compared before and during an episode.

Which inference is strongest?

2. Blood is moved from an active-tissue environment with low and high to an alveolar environment with high and low . Which paired change is expected?

3. External intercostal muscle activity is selectively blocked during an attempted quiet inspiration, while diaphragm contraction remains normal. Which pattern is most likely?

4. Match each respiratory term with its appropriate description. A Column II entry is used once.

5. A spirogram marks point X at the end of a normal inspiration and point Y at the end of a normal expiration. No airflow occurs at either instant. Which interpretation is correct?

6. Consider the following statements.
I. An earthworm depends on a moist cuticle for gaseous exchange.
II. An insect uses branching tracheal tubes to transport atmospheric air inside the body.
III. Earthworms and insects both use vascularised gills as their principal respiratory organs.
IV. In both animals, gases enter exclusively by diffusion over the entire general body surface.

7. Two inspiratory measurements end at the same maximum lung-volume level. Measurement P begins after a normal expiration, while measurement Q begins after a normal inspiration. P must include:

8. Two similar flatworms are placed in equally oxygenated water. The outer surface of specimen P remains exposed, whereas specimen Q receives a harmless but gas-impermeable coating over most of its body. Q soon shows reduced activity. Which inference is best supported?

9. Arrange the following events in the bicarbonate-mediated transport of carbon dioxide from tissues to alveoli.
P. Bicarbonate is formed in blood near tissues.
Q. Carbon dioxide diffuses from alveolar blood into alveolar air.
R. Tissue carbon dioxide enters blood.
S. Bicarbonate is converted back toward carbon dioxide near alveoli.

10. Assertion: The conducting and exchange parts of the respiratory system have different wall designs.
Reason: The conducting part filters, humidifies and warms inspired air.

11. The pulmonary oxygen gradient is , while the pulmonary carbon-dioxide gradient is . Which interpretation is correct?

12. Assertion: Extensive vascularisation is an important adaptation of the alveolar exchange surface.
Reason: Carbon dioxide is approximately times more soluble than oxygen.

13. Region P exchanges oxygen across a thin membrane with a large partial-pressure gradient. Region Q exchanges carbon dioxide across a markedly thicker membrane with a smaller gradient. Surface area and blood flow are equal. Which conclusion is most scientifically justified without measured transfer rates?

14. Air reaches the terminal bronchioles normally in an experimental lung model, but the walls of the alveolar ducts and alveoli become thick and strongly supported like larger conducting airways. Pulmonary blood flow remains normal. Which effect is most directly expected?

15. A graph plots on the horizontal axis and percentage saturation of haemoglobin with oxygen on the vertical axis. The curve rises slowly at first, then steeply, and finally approaches a plateau. This graph is:

16. During swallowing, a food bolus and inspired air have both recently passed through the pharyngeal region. Their routes then differ most directly in that:

17. Match each respiratory step with its most appropriate description. A Column II entry is used once.

18. A student's record links each process with a site and an immediate event.

Which evaluation best fits the record?

19. Person P breathes with . Person Q breathes with . How much total tidal air does each move in ?

20. Consider the following statements about the human conducting pathway.
I. The trachea follows the larynx.
II. Primary bronchi branch into secondary and tertiary bronchi.
III. Terminal bronchioles occur before primary bronchi.
IV. The pharynx lies upstream of the larynx in the respiratory route.

21. Alveolar diffusion remains normal, but the blood can no longer transport respiratory gases effectively from the lungs to systemic tissues. Which outcome is most likely?

22. Consider the following statements about occupational respiratory disorders.
I. Prolonged exposure to industrial dust may overwhelm normal defensive mechanisms.
II. Continued exposure can produce inflammation.
III. Inflammation may progress to fibrosis and lung damage.
IV. Protective masks can reduce inhalation of harmful dust.

23. Arrange the events that increase carbon-dioxide elimination when cellular metabolism rises.
P. Ventilation increases.
Q. Cellular production of rises.
R. Chemosensitive regions detect increased and .
S. More carbon dioxide is removed through the alveoli.
T. Respiratory neural activity is adjusted.

24. Four pathway records are shown below.

Which pair correctly represents two consecutive portions of the conducting pathway?

25. Consider the following statements about the pulmonary diffusion membrane.
I. It includes the squamous epithelium of the alveolus.
II. Basement substance lies between the epithelial and endothelial layers.
III. Capillary endothelium forms its blood-side cellular layer.
IV. The red blood cell membrane is counted as one of its three principal layers.

26. Tidal volume increases by , while inspiratory reserve volume decreases by . All other values remain unchanged. What happens to inspiratory capacity?

27. Four individuals have the same of but different residual volumes.

Who has the greatest vital capacity?

28. During an attempted inspiration with an open airway, atmospheric pressure is and intra-pulmonary pressure is . At the same moment, alveolar is experimentally held at and incoming pulmonary blood has . Which paired directions follow from the stated gradients?

29. Blood entering pulmonary capillaries has low and high . After passing an alveolus, it leaves with higher and lower , then reaches systemic tissues where the opposite changes occur. Which circuit description is correct?

30. Airway diameter is restored to normal in two patients. Patient P previously had inflamed bronchioles with intact alveoli. Patient Q has permanently destroyed alveolar walls. Which outcome is most likely?

31. Four breathing-phase records are shown below.

Which record is fully consistent with pressure-driven airflow?

32. Two lung regions receive air of the same composition. Region P has thin alveolar walls and normal capillary flow. Region Q has thickened alveolar walls and markedly reduced capillary flow. Gas transfer is lower in Q. The strongest conclusion is that effective alveolar exchange depends on:

33. Arrange the following compartments in decreasing order of their approximate .
P. Atmospheric air
Q. Alveoli
R. Oxygenated blood
S. Deoxygenated blood
T. Tissues

34. Consider the following statements about carbamino-haemoglobin.
I. Approximately of transported carbon dioxide is associated with haemoglobin.
II. Its formation depends mainly on .
III. also influences carbon-dioxide association with haemoglobin.
IV. Carbamino-haemoglobin formation is independent of both respiratory-gas partial pressures.

35. Two respiratory regions are compared.

Region P and Region Q are respectively:

36. Alveolar is experimentally raised until it equals the of deoxygenated blood arriving at the lungs. What immediate change is most likely?

37. Initially, a person has , frequency , and . Later, frequency rises to , falls to , and and are unchanged. What happens to minute tidal air movement and vital capacity?

38. Inspired air and swallowed food share one passage before separating. Which sequence correctly traces inspired air immediately after this shared region?

39. Assertion: Incomplete cartilaginous rings continue into the walls of alveoli.
Reason: Alveoli require very thin walls for efficient gaseous exchange.

40. Atmospheric is approximately , whereas alveolar is about . Which explanation best accounts for this difference?

41. A tracer starts in alveolar air and is detected successively in a thin epithelial layer, an intervening non-cellular region and then a second thin cellular layer immediately before entering capillary plasma. The last cellular layer is identified as:

42. Oxygenated blood and surrounding tissues are experimentally maintained at the same of . Other factors remain unchanged. What is expected at that interface?

43. Two oxygen-dissociation curves are recorded at the same range of . Curve P shows greater haemoglobin saturation than curve Q at each compared value. Which assignment best fits the two experimental conditions?

44. Consider the following statements about oxygen unloading in tissues.
I. Low tissue favours oxyhaemoglobin dissociation.
II. High tissue and high concentration favour oxygen release.
III. Lower temperature in highly active tissues is the major condition promoting dissociation.
IV. Higher tissue temperature can support unloading.

45. Four records describe events during a breathing phase.

Which record correctly represents quiet expiration?

46. Which record is internally consistent with all three capacity formulae shown?

47. Blood entering pulmonary capillaries is experimentally given a of , while alveolar air remains at . What happens initially?

48. A long-term cigarette smoker develops progressive breathlessness. The bronchi are not described as inflamed, but imaging shows widespread destruction of alveolar walls and a reduced exchange surface. The most appropriate diagnosis is:

49. Which symbolic relation correctly represents both phases of a quiet breathing cycle?

50. A spirometric record provides reliable values for , and , but no value involving residual air is available. Which group of capacities can still be calculated completely?