NEET 2025 MCQ with Answer Explanation : Breathing and Exchange of Gases.

MCQ 31:
What structure divides the nasal cavity from the oral cavity?

A) Uvula

B) Epiglottis

C) Hard palate

D) Soft palate

Answer: C) Hard palate

Explanation: The hard palate separates the nasal cavity from the oral cavity, facilitating breathing and eating simultaneously.

MCQ 32:
Which respiratory condition is primarily characterized by wheezing and difficulty in breathing due to airway constriction?

A) Pneumonia

B) Asthma

C) Bronchitis

D) Emphysema

Answer: B) Asthma

Explanation: Asthma is characterized by wheezing and difficulty breathing due to inflammation and constriction of the airways.

MCQ 33:
The respiratory system helps regulate which of the following?

A) Blood glucose levels

B) Blood pH levels

C) Blood pressure

D) Body temperature

Answer: B) Blood pH levels

Explanation: The respiratory system plays a critical role in regulating blood pH by controlling the levels of carbon dioxide in the blood.

MCQ 34:
The air we breathe is predominantly composed of which gas?

A) Carbon dioxide

B) Nitrogen

C) Oxygen

D) Argon

Answer: B) Nitrogen

Explanation: The atmosphere is approximately 78% nitrogen, making it the most abundant gas we breathe.

MCQ 35:
What is the primary role of the alveolar epithelium?

A) To filter air

B) To facilitate gas exchange

C) To produce surfactant

D) To regulate airflow

Answer: B) To facilitate gas exchange

Explanation: The alveolar epithelium is primarily responsible for the exchange of oxygen and carbon dioxide between the air and the blood.

MCQ 36:
Which term refers to the volume of air remaining in the lungs after a maximal exhalation?

A) Tidal volume

B) Residual volume

C) Vital capacity

D) Inspiratory reserve volume

Answer: B) Residual volume

Explanation: Residual volume is the amount of air that remains in the lungs after a forceful exhalation, preventing lung collapse.

MCQ 37:
Which of the following structures is NOT part of the conducting zone of the respiratory system?

A) Trachea

B) Bronchi

C) Alveoli

D) Nasal cavity

Answer: C) Alveoli

Explanation: The conducting zone includes structures that transport air but do not participate in gas exchange. The alveoli are part of the respiratory zone.

MCQ 38:
In the human respiratory system, gas exchange occurs primarily through what type of diffusion?

A) Simple diffusion

B) Facilitated diffusion

C) Active transport

D) Osmosis

Answer: A) Simple diffusion

Explanation: Gas exchange occurs by simple diffusion, where oxygen and carbon dioxide move from areas of higher concentration to areas of lower concentration.

MCQ 39:
Which of the following is the most effective method for increasing lung capacity?

A) Breathing through the mouth

B) Deep breathing exercises

C) Rapid shallow breathing

D) Holding breath for long periods

Answer: B) Deep breathing exercises

Explanation: Deep breathing exercises help to expand the lungs and increase lung capacity by fully utilizing the respiratory system.

MCQ 40:
What is the primary function of the nasal cavity?

A) To produce sound

B) To warm and moisten inhaled air

C) To filter blood

D) To facilitate gas exchange

Answer: B) To warm and moisten inhaled air

Explanation: The nasal cavity helps to warm and humidify the air before it reaches the lungs, as well as filter out particles.