250+ TOP MCQs on Human Respiratory System and Answers

Biology Multiple Choice Questions on “Human Respiratory System – 1”.

1. Which of the following is not part of the human respiratory system?
a) Pharynx
b) Alveoli
c) Trachea
d) Lumen
Answer: d
Clarification: Lumen is not a part of the human respiratory system whereas it belongs to the digestive system. Lumen increases the surface area for the absorption of food. Pharynx, alveoli, and trachea are part of respiratory system.

2. The common passage for both food and air is called the esophagus.
a) True
b) False
Answer: b
Clarification: It is a wrong statement. The pharynx is a common passage for both food and air. Esophagus also is known as food pipe is part of the digestive system, that allows passage of food from mouth to stomach.

3. Which of the following part is known as the soundbox of our body system?
a) Vocal gland
b) Pharynx
c) Larynx
d) Nasopharynx
Answer: c
Clarification: Larynx is known as the soundbox of our body system. It is made of cartilage and helps in production of sound, hence the name soundbox. The larynx is guarded by epiglottis. Also, larynx helps in regulation of our pitch and volume.

4. ________ prevents the food from entering into the glottis during swallowing.
a) Larynx
b) Peri glottis
c) Post glottis
d) Epiglottis
Answer: d
Clarification: Epiglottis prevents the food from entering into glottis during swallowing. It is a thin elastic cartilaginous flap. And if the food enters into the glottis, then it can lead to severe coughing or choking.

5. At which thoracic vertebrae does the trachea branch?
a) Sixth
b) Fourth
c) Fifth
d) Second
Answer: c
Clarification: The trachea is a straight tube that extends up to the mid-thoracic cavity. It divides at the fifth thoracic vertebra into left and right bronchi. The first division of the respiratory system occurs through trachea.

6. Trachea, bronchi, and bronchioles are all supported by _______
a) incomplete cartilaginous rings
b) complete cartilaginous rings
c) in-cartilaginous rings
d) bones
Answer: a
Clarification: Trachea, bronchi, and bronchioles are all supported by incomplete cartilaginous rings. They are actually hyaline cartilage and this is strong enough to hold the mentioned parts. They are also supported by a small smooth muscle at the end of the trachea.

7. Which of the following is not a characteristic of alveoli?
a) Thick
b) Thin
c) Irregular walled
d) Vascularized
Answer: a
Clarification: Alveoli is a thin, irregular walled and vascularized bag-like structure. It is the main site for diffusion of gases. Terminal bronchioles give rise to alveoli. Lungs without alveoli is a dead lung as they play a major role in respiration.

8. Which network comprises the lung?
a) Bronchi and bronchioles
b) Trachea, tracheoles
c) Bronchi, bronchioles, and alveoli
d) Trachea only
Answer: c
Clarification: Bronchi, bronchioles, and alveoli together comprise the lung. They are the main vital organs compared to other secondary parts. They have a perfect network for respiration to take place.

9. Trachea is a straight tube extending up to the ________
a) end of pharynx
b) middle of larynx
c) posterior of the thoracic cavity
d) anterior of the thoracic cavity
Answer: d
Clarification: Trachea is a straight tube extending up to the anterior part of the thoracic cavity. It is also known as the windpipe. The trachea connects the soundbox to the bronchi. Also, it provides the passage for air.

10. Pleura is _______ layered.
a) Not
b) Single
c) Double
d) Triple
Answer: c
Clarification: Pleura is doubled layered. It protects the lungs. Also, there is a fluid called pleural fluid present between the pleura. It reduces the friction between the surfaces of the lungs.

11. In which respiratory part does the diffusion of gas take place?
a) Alveoli
b) Bronchi
c) Bronchioles
d) Trachea
Answer: a
Clarification: Alveoli is the part where the diffusion of gases takes place. It exchanges oxygen and carbon dioxide between the bloodstream. They are arranged as small balloon clusters throughout the lungs.

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