Breathing and Exchange of Gases

32 NEET-UG practice questions on Breathing and Exchange of Gases, part of Zoology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Easy

   Earthworms exchange gases through their

   1. Amoist cuticle
   2. Blungs
   3. Ctracheal tubes
   4. Dgills

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   Answer: A · moist cuticle

   Earthworms use their moist cuticle for gas exchange. Insects use tracheal tubes, and many aquatic animals use gills.

   • B: Lungs are used by terrestrial vertebrates.
   • C: Tracheal tubes are used by insects.
   • D: Gills are used by aquatic arthropods, molluscs and fishes.

   Remember this

   Earthworm uses moist cuticle; insects use tracheae; fishes use gills; frogs use skin and lungs.

2. Question 2 · Hard

   Read these statements on regulation and disorders: A. Receptors in the aortic arch and carotid artery recognise changes in CO₂ and H⁺ concentration. B. Oxygen has the major role in regulating the respiratory rhythm. C. Emphysema increases the respiratory surface of the lungs. D. A chemosensitive area next to the rhythm centre is highly sensitive to CO₂ and H⁺. Which of these are correct?

   1. AB and C only
   2. BA and D only
   3. CA, B and D only
   4. DA, C and D only

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   Answer: B · A and D only

   A and D are true. The role of oxygen in regulating respiration is quite insignificant, so B fails. Emphysema damages alveolar walls and reduces the respiratory surface, so C fails.

   • A: A and D are the true ones, not B and C.
   • C: B fails, as oxygen's role is insignificant.
   • D: C fails, as emphysema reduces the surface.

   Remember this

   CO₂ and H⁺ drive rhythm regulation; emphysema is often caused by cigarette smoking.

3. Question 3 · Easy

   Roughly what share of carbon dioxide is carried in blood as bicarbonate?

   1. AAbout 97 per cent
   2. BAbout 7 per cent
   3. CAbout 20-25 per cent
   4. DAbout 70 per cent

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   Answer: D · About 70 per cent

   About 70 per cent of CO₂ goes as bicarbonate, about 20-25 per cent as carbamino-haemoglobin, and about 7 per cent dissolved in plasma.

   • A: This is the share of oxygen carried by RBCs.
   • B: This is the share dissolved in plasma.
   • C: This is the carbamino-haemoglobin share.

   Remember this

   Oxygen is 97 per cent via RBCs; CO₂ is 70 per cent via bicarbonate.

4. Question 4 · Hard

   The pO₂ difference across the alveolar membrane is about 64 mm Hg, but the pCO₂ difference is only about 5 mm Hg. Even so, CO₂ diffuses adequately because

   1. Aits solubility is 20-25 times that of oxygen
   2. Bits molecules diffuse only through the plasma
   3. Cthe membrane is thinner on the side where CO₂ leaves
   4. Dhaemoglobin carries it across the membrane

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   Answer: A · its solubility is 20-25 times that of oxygen

   The amount that can diffuse depends on solubility as well as the pressure gradient. CO₂ is 20-25 times more soluble than O₂, so more CO₂ can cross per unit difference in partial pressure.

   • B: This gives no reason for greater transfer.
   • C: The same thin membrane serves both gases.
   • D: Haemoglobin does not cross the membrane.

   Remember this

   Diffusion across the membrane depends on the pressure gradient, solubility and membrane thickness.

5. Question 5 · Easy

   A thin, elastic cartilaginous flap prevents food from entering the larynx during swallowing. This flap is the

   1. Aglottis
   2. Bepiglottis
   3. Cpleura
   4. Dtertiary bronchus

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   Answer: B · epiglottis

   The epiglottis covers the glottis during swallowing, which keeps food out of the larynx.

   • A: The glottis is the opening, not the flap.
   • C: Pleura is the double membrane around the lungs.
   • D: A bronchus is an air passage in the lungs.

   Remember this

   Glottis is the opening; epiglottis is the flap that closes it during swallowing.

6. Question 6 · Medium

   Given below are two statements: Statement I: Contraction of the diaphragm increases the thoracic volume in the antero-posterior axis. Statement II: The pneumotaxic centre in the pons can reduce the duration of inspiration. Choose the correct answer.

   1. AStatement I is correct but Statement II is incorrect
   2. BBoth Statement I and Statement II are correct
   3. CStatement I is incorrect but Statement II is correct
   4. DBoth Statement I and Statement II are incorrect

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   Assertion A: Oxygen dissociates from oxyhaemoglobin readily in the tissues. Reason R: Low pO₂, high pCO₂, high H⁺ concentration and higher temperature prevail in the tissues. Choose the correct answer.

   1. ABoth A and R are correct and R is the correct explanation of A
   2. BA is not correct but R is correct
   3. CA is correct but R is not correct
   4. DBoth A and R are correct but R is not the correct explanation of A

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8. Question 8 · Medium

   Arrange these structures in the order in which inhaled air passes through them. A. Primary bronchi B. Larynx C. Terminal bronchioles D. Nasopharynx

   1. AB, D, A, C
   2. BD, B, C, A
   3. CD, A, B, C
   4. DD, B, A, C

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9. Question 9 · Medium

   Match List-I with List-II. List-I (site) A. Atmospheric air B. Alveoli C. Oxygenated blood D. Deoxygenated blood List-II (typical pO₂ in mm Hg) I. 95 II. 40 III. 159 IV. 104

   1. AA-III, B-I, C-IV, D-II
   2. BA-IV, B-III, C-I, D-II
   3. CA-III, B-IV, C-I, D-II
   4. DA-III, B-IV, C-II, D-I

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10. Question 10 · Medium

    The lung volumes of an adult are: tidal volume 500 mL, inspiratory reserve volume 2500 mL, expiratory reserve volume 1000 mL, residual volume 1200 mL. Find the functional residual capacity.

    1. A4000 mL
    2. B5200 mL
    3. C2200 mL
    4. D3000 mL

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11. Question 11 · Medium

    Under normal conditions, every 100 mL of oxygenated blood delivers about 5 mL of O₂ to the tissues. If a person's cardiac output is 5000 mL/min, about how much O₂ reaches the tissues each minute?

    1. A250 mL
    2. B2500 mL
    3. C25 mL
    4. D200 mL

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12. Question 12 · Medium

    Spirometry of an adult gives: tidal volume 450 mL, inspiratory reserve volume 2600 mL, expiratory reserve volume 1050 mL and residual volume 1150 mL. What is the total lung capacity?

    1. A5700 mL
    2. B5250 mL
    3. C4100 mL
    4. D3050 mL

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13. Question 13 · Hard

    Here are four statements on the transport of gases. A. About 20-25 per cent of carbon dioxide is carried as carbamino-haemoglobin. B. Carbonic anhydrase is present in very high concentration in RBCs and in minute quantities in plasma. C. About 7 per cent of oxygen is carried in a dissolved state through plasma. D. Binding of oxygen with haemoglobin is favoured by high pCO₂ and high H⁺ concentration. Which of these are correct?

    1. AA, B and C only
    2. BB and D only
    3. CA, C and D only
    4. DA and B only

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14. Question 14 · Medium

    Assertion A: Binding of carbon dioxide with haemoglobin is favoured in the tissues. Reason R: Every 100 mL of deoxygenated blood delivers about 4 mL of carbon dioxide to the alveoli. Choose the correct answer.

    1. AA is correct but R is not correct
    2. BBoth A and R are correct but R is not the correct explanation of A
    3. CA is not correct but R is correct
    4. DBoth A and R are correct and R is the correct explanation of A

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15. Question 15 · Easy

    Long-term cigarette smoking can damage the alveolar walls and reduce the respiratory surface. This chronic disorder is

    1. Aemphysema
    2. Bpneumonia
    3. Casthma
    4. Doccupational fibrosis

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16. Question 16 · Medium

    Arrange these events of normal inspiration in the order in which they occur. A. Pulmonary volume increases. B. The diaphragm and external intercostal muscles contract. C. Intra-pulmonary pressure falls below atmospheric pressure. D. The volume of the thoracic chamber increases. Choose the correct order.

    1. AB, A, D, C
    2. BD, B, C, A
    3. CB, D, A, C
    4. DB, D, C, A

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17. Question 17 · Easy

    Contraction of the diaphragm increases the volume of the thoracic chamber along which axis?

    1. ANo axis, as it decreases the volume
    2. BAntero-posterior axis
    3. CDorso-ventral axis
    4. DLateral axis only

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18. Question 18 · Hard

    Read these statements about the regulation of breathing. A. The respiratory rhythm centre lies in the medulla. B. The pneumotaxic centre in the pons can reduce the duration of inspiration and so alter the respiratory rate. C. The chemosensitive area next to the rhythm centre responds mainly to a fall in O₂ concentration. D. Receptors in the aortic arch and carotid artery can recognise changes in CO₂ and H⁺ concentration. Which of these are correct?

    1. AA, B, C and D
    2. BA and B only
    3. CA, B and D only
    4. DB, C and D only

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19. Question 19 · Medium

    Given below are two statements: Statement I: Low pO₂, high pCO₂, high H⁺ concentration and higher temperature favour dissociation of oxygen from oxyhaemoglobin. Statement II: Nearly 20-25 per cent of carbon dioxide is transported by red blood cells as carbamino-haemoglobin. Choose the correct answer.

    1. ABoth Statement I and Statement II are correct
    2. BBoth Statement I and Statement II are incorrect
    3. CStatement I is correct but Statement II is incorrect
    4. DStatement I is incorrect but Statement II is correct

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20. Question 20 · Medium

    A man's vital capacity is 4600 mL, his expiratory reserve volume is 1100 mL and his tidal volume is 500 mL. What is his inspiratory capacity?

    1. A4100 mL
    2. B3500 mL
    3. C3000 mL
    4. D5700 mL

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21. Question 21 · Medium

    Match List-I with List-II for a healthy adult man. List-I (Volume) A. Tidal volume B. Inspiratory reserve volume C. Expiratory reserve volume D. Residual volume List-II (Approximate value) I. 1100-1200 mL II. 500 mL III. 2500-3000 mL IV. 1000-1100 mL

    1. AA-II, B-IV, C-III, D-I
    2. BA-II, B-III, C-I, D-IV
    3. CA-IV, B-III, C-II, D-I
    4. DA-II, B-III, C-IV, D-I

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22. Question 22 · Medium

    Given below are two statements: Statement I: About 7 per cent of carbon dioxide is carried in a dissolved state through plasma. Statement II: Under normal conditions, every 100 mL of oxygenated blood delivers about 4 mL of oxygen to the tissues. Choose the correct answer.

    1. AStatement I is correct but Statement II is incorrect
    2. BBoth Statement I and Statement II are correct
    3. CStatement I is incorrect but Statement II is correct
    4. DBoth Statement I and Statement II are incorrect

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23. Question 23 · Medium

    A person at rest breathes 15 times a minute with a tidal volume of 500 mL. How much air does the person inspire in 2 minutes?

    1. A7.5 L
    2. B30 L
    3. C15 L
    4. D1 L

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24. Question 24 · Easy

    Roughly what percentage of oxygen in the blood is transported by the red blood cells?

    1. A3 per cent
    2. B70 per cent
    3. C97 per cent
    4. D25 per cent

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25. Question 25 · Easy

    The cartilaginous box that helps in sound production is the

    1. Apharynx
    2. Blarynx
    3. Cepiglottis
    4. Dtrachea

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