Breathing and Exchange of Gases – Daily Practice Problem (DPP)

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🎯 NEET 2026 Daily Practice Problem (DPP)

Topic: Breathing and Exchange of Gases | 20 High-Yield MCQs

Q1. Earthworms use which of the following for respiration?

  1. Tracheal tubes
  2. Moist cuticle
  3. Gills
  4. Lungs
✅ View Answer & Explanation

Correct Answer: (2) Moist cuticle
Explanation: Earthworms breathe through their moist skin (cuticle), while insects use tracheal tubes and aquatic arthropods use gills.

Q2. The structure which prevents the entry of food into the larynx is:

  1. Glottis
  2. Epiglottis
  3. Pharynx
  4. Bronchi
✅ View Answer & Explanation

Correct Answer: (2) Epiglottis
Explanation: During swallowing, the glottis is covered by a thin elastic cartilaginous flap called the epiglottis to prevent food from entering the larynx.

Q3. The volume of air inspired or expired during a normal respiration is called:

  1. Inspiratory Reserve Volume (IRV)
  2. Residual Volume (RV)
  3. Tidal Volume (TV)
  4. Expiratory Reserve Volume (ERV)
✅ View Answer & Explanation

Correct Answer: (3) Tidal Volume (TV)
Explanation: Tidal volume is approximately 500 mL in a healthy man, totaling about 6000 to 8000 mL per minute.

Q4. Vital Capacity (VC) is equal to:

  1. TV + IRV + ERV
  2. TV + IRV + RV
  3. ERV + RV
  4. TV + ERV
✅ View Answer & Explanation

Correct Answer: (1) TV + IRV + ERV
Explanation: Vital capacity is the maximum volume of air a person can breathe in after a forced expiration.

Q5. What is the partial pressure of $O_2$ ($pO_2$) in alveolar air?

  1. 40 mm Hg
  2. 95 mm Hg
  3. 104 mm Hg
  4. 159 mm Hg
✅ View Answer & Explanation

Correct Answer: (3) 104 mm Hg
Explanation: Alveolar $pO_2$ is 104 mm Hg, while $pCO_2$ is 40 mm Hg. This gradient allows $O_2$ to diffuse into the blood.

Q6. About 70% of $CO_2$ is transported in the blood as:

  1. Carbamino-haemoglobin
  2. Bicarbonate ions
  3. Dissolved in plasma
  4. Carbonic acid
✅ View Answer & Explanation

Correct Answer: (2) Bicarbonate ions
Explanation: 70% of $CO_2$ is carried as bicarbonate, 20-25% as carbamino-haemoglobin, and 7% dissolved in plasma.

Q7. The oxygen dissociation curve is:

  1. Linear
  2. Sigmoid
  3. Hyperbolic
  4. Parabolic
✅ View Answer & Explanation

Correct Answer: (2) Sigmoid
Explanation: The sigmoid shape is due to the cooperative binding of oxygen to haemoglobin.

Q8. Which of the following factors shifts the oxygen-haemoglobin dissociation curve to the right?

  1. Low pCO_2
  2. High pH
  3. High H+ concentration
  4. Low temperature
✅ View Answer & Explanation

Correct Answer: (3) High H+ concentration
Explanation: Conditions in tissues (High pCO_2, High H+, High temp) favor dissociation of O_2 from haemoglobin, shifting the curve to the right.

Q9. The pneumotaxic centre, which can moderate the functions of the respiratory rhythm centre, is located in:

  1. Medulla oblongata
  2. Pons varolii
  3. Cerebellum
  4. Cerebrum
✅ View Answer & Explanation

Correct Answer: (2) Pons varolii
Explanation: The respiratory rhythm centre is in the medulla, while the pneumotaxic centre is in the pons.

Q10. Asthma is caused due to:

  1. Inflammation of bronchi and bronchioles
  2. Infection of the lungs
  3. Bleeding in the pleural cavity
  4. Damage to the diaphragm
✅ View Answer & Explanation

Correct Answer: (1) Inflammation of bronchi and bronchioles
Explanation: Asthma is a respiratory disorder characterized by wheezing due to inflammation and narrowing of the airways.

Q11. Every 100 mL of deoxygenated blood delivers approximately how much $CO_2$ to the alveoli?

  1. 2 mL
  2. 4 mL
  3. 5 mL
  4. 10 mL
✅ View Answer & Explanation

Correct Answer: (2) 4 mL
Explanation: Every 100 mL of oxygenated blood delivers 5 mL of $O_2$ to tissues, and 100 mL of deoxygenated blood delivers 4 mL of $CO_2$ to alveoli.

Q12. Occupational respiratory disorders like Silicosis are common in:

  1. Chemical industries
  2. Stone breaking and grinding industries
  3. Food processing plants
  4. Textile mills
✅ View Answer & Explanation

Correct Answer: (2) Stone breaking and grinding industries
Explanation: Prolonged exposure to dust leads to fibrosis (proliferation of fibrous tissue), causing serious lung damage.

Q13. What is the site of actual gaseous exchange in humans?

  1. Nostrils
  2. Trachea
  3. Bronchioles
  4. Alveoli
✅ View Answer & Explanation

Correct Answer: (4) Alveoli
Explanation: Alveoli and their ducts form the respiratory or exchange part of the respiratory system.

Q14. The conducting part of the respiratory system ends at:

  1. Trachea
  2. Primary bronchi
  3. Terminal bronchioles
  4. Alveoli
✅ View Answer & Explanation

Correct Answer: (3) Terminal bronchioles
Explanation: The system from nostrils up to terminal bronchioles is the conducting part; alveoli and ducts are the exchange part.

Q15. Emphysema is characterized by:

  1. Damage to alveolar walls
  2. Fluid accumulation in lungs
  3. Bacterial infection of bronchi
  4. Spasm of smooth muscles
✅ View Answer & Explanation

Correct Answer: (1) Damage to alveolar walls
Explanation: Chronic smoking is a major cause of emphysema, where the respiratory surface is decreased due to alveolar wall damage.

Q16. During inspiration, the diaphragm:

  1. Relaxes and becomes dome-shaped
  2. Contracts and becomes flattened
  3. Remains unchanged
  4. Moves upwards
✅ View Answer & Explanation

Correct Answer: (2) Contracts and becomes flattened
Explanation: Contraction of the diaphragm increases the volume of the thoracic chamber in the antero-posterior axis.

Q17. The amount of air that remains in the lungs after a normal expiration is:

  1. Residual Volume
  2. Expiratory Capacity
  3. Functional Residual Capacity (FRC)
  4. Total Lung Capacity
✅ View Answer & Explanation

Correct Answer: (3) Functional Residual Capacity (FRC)
Explanation: FRC = ERV + RV. It is the air left after a normal, passive breath out.

Q18. The diffusion membrane consists of how many layers?

  1. Two
  2. Three
  3. Four
  4. Five
✅ View Answer & Explanation

Correct Answer: (2) Three
Explanation: The membrane has 3 layers: Alveolar squamous epithelium, capillary endothelium, and the basement substance in between.

Q19. Carbonic anhydrase is found in high concentration in:

  1. Plasma
  2. RBCs
  3. WBCs
  4. Platelets
✅ View Answer & Explanation

Correct Answer: (2) RBCs
Explanation: Erythrocytes contain a high concentration of carbonic anhydrase to facilitate the formation of bicarbonates. Tiny amounts are present in plasma.

Q20. Which gas has the highest solubility in the blood?

  1. O_2
  2. N_2
  3. CO_2
  4. CO
✅ View Answer & Explanation

Correct Answer: (3) CO_2
Explanation: The solubility of CO_2 is 20-25 times higher than that of O_2, allowing it to diffuse faster through the membrane.

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