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Breathing and respiration: NEET MCQs with answers

144 questions on this topic of Human Physiology (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. On average, a healthy human breathes how many times per minute?

  1. 4–6 times
  2. 30–40 times
  3. 12–16 times
  4. 60–72 times
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Answer: (C) 12–16 times

A healthy human breathes 12–16 times per minute; the volume of air involved can be estimated using a spirometer.

medium

2. The part of the respiratory system starting from the external nostrils up to the terminal bronchioles is called the:

  1. Conducting part
  2. Respiratory or exchange part
  3. Diffusion membrane
  4. Alveolar part
Show answer and explanation

Answer: (A) Conducting part

The conducting part (nostrils to terminal bronchioles) transports air, clears it of foreign particles, humidifies it and brings it to body temperature; the alveoli and their ducts form the respiratory or exchange part.

hard

3. How many of the following are correctly matched? (i) Pneumotaxic centre – pons (ii) Rhythm centre – medulla (iii) Emphysema – inflammation of bronchi (iv) Asthma – damaged alveolar walls (v) Carbonic anhydrase – RBCs

  1. Two
  2. Three
  3. Four
  4. Five
Show answer and explanation

Answer: (B) Three

(i), (ii) and (v) are correct. Emphysema involves damaged alveolar walls and asthma involves inflammation of bronchi and bronchioles, so (iii) and (iv) are wrong.

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4. The conducting part of the respiratory system, from the nostrils to the terminal bronchioles:

  1. Produces blood cells
  2. Transports, cleans, humidifies and warms the inhaled air
  3. Is the site of gas exchange
  4. Contains only alveoli
Show answer and explanation

Answer: (B) Transports, cleans, humidifies and warms the inhaled air

The conducting part transports atmospheric air to the alveoli, clears it of foreign particles, humidifies it and brings it to body temperature. The exchange part (alveoli and ducts) is the site of diffusion.

NCERT Class 11

easy

5. Tidal volume = 450 mL, inspiratory reserve volume = 2900 mL and expiratory reserve volume = 1000 mL. The vital capacity is:

  1. 1450 mL
  2. 3900 mL
  3. 4350 mL
  4. 3350 mL
Show answer and explanation

Answer: (C) 4350 mL

VC = TV + IRV + ERV = 450 + 2900 + 1000 = 4350 mL.

hard

6. Total lung capacity (TLC) is the total volume of air accommodated in the lungs at the end of a forced inspiration. It equals:

  1. TV + IRV
  2. RV + ERV + TV + IRV, i.e. vital capacity + residual volume
  3. ERV + RV
  4. VC − RV
Show answer and explanation

Answer: (B) RV + ERV + TV + IRV, i.e. vital capacity + residual volume

TLC includes RV, ERV, TV and IRV; it is vital capacity plus residual volume.

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7. The thin elastic cartilaginous flap that prevents the entry of food into the larynx during swallowing is the:

  1. Epiglottis
  2. Glottis
  3. Uvula
  4. Trachea
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Answer: (A) Epiglottis

During swallowing the glottis is covered by the epiglottis, a thin elastic cartilaginous flap that prevents food entering the larynx.

medium

8. About 97 per cent of oxygen is transported in blood by:

  1. Platelets
  2. RBCs, as oxyhaemoglobin
  3. Plasma in dissolved form
  4. Bicarbonate ions
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Answer: (B) RBCs, as oxyhaemoglobin

About 97 per cent of O2 is carried by RBCs bound to haemoglobin; the remaining 3 per cent is dissolved in plasma.

NCERT Class 11

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9. The solubility of CO2 is how many times higher than that of O2?

  1. 100 times
  2. 2–3 times
  3. 20–25 times
  4. Equal
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Answer: (C) 20–25 times

CO2 is 20–25 times more soluble than O2, so the amount of CO2 that can diffuse through the diffusion membrane per unit difference in partial pressure is much higher.

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10. In industries involving grinding or stone breaking, so much dust is produced that the body's defences cannot fully cope. Long exposure can cause:

  1. Asthma only due to pollen
  2. Inflammation leading to fibrosis (proliferation of fibrous tissues) and serious lung damage
  3. Emphysema only due to smoking
  4. Diabetes insipidus
Show answer and explanation

Answer: (B) Inflammation leading to fibrosis (proliferation of fibrous tissues) and serious lung damage

Occupational respiratory disorders arise from long exposure to dust, causing inflammation and fibrosis; workers in such industries should wear protective masks.

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11. The trachea, bronchi and initial bronchioles are supported by:

  1. Complete bony rings
  2. Smooth muscle only
  3. Elastic fibres only
  4. Incomplete cartilaginous rings
Show answer and explanation

Answer: (D) Incomplete cartilaginous rings

The trachea, primary, secondary and tertiary bronchi, and initial bronchioles are supported by incomplete cartilaginous rings, which keep the airways open.

NCERT Class 11

medium

12. The pleural fluid between the two layers of pleura covering the lungs:

  1. Reduces friction on the lung surface
  2. Exchanges gases
  3. Produces surfactant
  4. Carries oxygen to blood
Show answer and explanation

Answer: (A) Reduces friction on the lung surface

The lungs are covered by a double-layered pleura with pleural fluid between the layers, which reduces friction on the lung surface.

NCERT Class 11

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