Q1. Which structure in the respiratory system is responsible for the exchange of oxygen and carbon dioxide in the lungs?
a) Alveoli
b) Trachea
c) Bronchi
d) Diaphragm
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Correct Answer: a) Alveoli
Explanation: Alveoli are small, air-filled sacs located at the ends of bronchioles in the lungs. They are the site of gas exchange, where oxygen from inhaled air diffuses into the bloodstream and carbon dioxide from the bloodstream diffuses into the alveolar air for exhalation.
Q2. What is the main function of the trachea in the respiratory system?
a) Gas exchange
b) Production of mucus
c) Passage of air to and from the lungs
d) Protection of the lungs from foreign particles
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Correct Answer: c) Passage of air to and from the lungs
Explanation: The trachea, also known as the windpipe, serves as a passageway for air to travel between the larynx and the bronchi of the lungs. It contains ciliated cells that help to remove mucus and foreign particles, protecting the lungs.
Q3. Which of the following is the correct pathway for air during inhalation in the human respiratory system?
a) Pharynx → Larynx → Trachea → Bronchi → Alveoli
b) Bronchi → Trachea → Larynx → Pharynx → Alveoli
c) Larynx → Trachea → Bronchi → Pharynx → Alveoli
d) Pharynx → Larynx → Bronchi → Trachea → Alveoli
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Correct Answer: d) Pharynx → Larynx → Bronchi → Trachea → Alveoli
Explanation: During inhalation, air enters the respiratory system through the nostrils or mouth, travels through the pharynx, passes the larynx, enters the trachea, then branches into the bronchi, and finally reaches the alveoli in the lungs for gas exchange.
Q4. What is the function of the diaphragm in the respiratory system?
a) To regulate airflow in the bronchi
b) To produce mucus for air filtration
c) To protect the lungs from infection
d) To help in breathing by contracting and relaxing
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Correct Answer: d) To help in breathing by contracting and relaxing
Explanation: The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. During inhalation, it contracts and flattens, increasing the volume of the thoracic cavity and causing air to be drawn into the lungs. During exhalation, it relaxes, allowing the lungs to deflate.
Q5. Which respiratory structure is responsible for filtering, warming, and humidifying inhaled air?
a) Bronchioles
b) Nasal cavity
c) Pharynx
d) Alveoli
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Correct Answer: b) Nasal cavity
Explanation: The nasal cavity contains mucous membranes and cilia that help to filter out dust, pollen, and other particles from inhaled air. Additionally, the nasal cavity warms and humidifies the air before it reaches the lungs, making it more suitable for gas exchange.
Q6. What role does surfactant play in the respiratory system?
a) It helps to regulate blood pH.
b) It prevents the collapse of alveoli during exhalation.
c) It aids in the production of mucus.
d) It assists in the absorption of oxygen into the bloodstream.
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Correct Answer: b) It prevents the collapse of alveoli during exhalation.
Explanation: Surfactant is a substance produced by type II alveolar cells in the lungs. It reduces surface tension within the alveoli, preventing them from collapsing during exhalation. This ensures that the alveoli remain open and facilitates gas exchange.
Q7. Which of the following structures is responsible for producing sound in humans?
a) Alveoli
b) Larynx
c) Pharynx
d) Trachea
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Correct Answer: b) Larynx
Explanation: The larynx, also known as the voice box, contains vocal cords that vibrate as air passes over them. These vibrations produce sound, allowing humans to speak and produce various vocalizations.
Q8. What is the function of the epiglottis during swallowing?
a) To close off the trachea and prevent food from entering it
b) To facilitate gas exchange in the lungs
c) To produce mucus for lubrication
d) To regulate airflow in the bronchi
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Correct Answer: a) To close off the trachea and prevent food from entering it
Explanation: The epiglottis is a flap of tissue located at the entrance to the trachea. During swallowing, it closes over the trachea, preventing food and liquids from entering the airway and directing them toward the esophagus instead.
Q9. Which part of the brain controls the basic rhythm of breathing?
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Hypothalamus
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Correct Answer: c) Medulla oblongata
Explanation: The medulla oblongata, located in the brainstem, contains respiratory centers that regulate the basic rhythm of breathing. It receives input from chemoreceptors and other sensory receptors to adjust breathing rate and depth as needed to maintain homeostasis.
Q10. What is the primary function of the bronchi in the respiratory system?
a) Gas exchange
b) Production of mucus
c) Passage of air to and from the lungs
d) Protection of the lungs from infection
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Correct Answer: c) Passage of air to and from the lungs
Explanation: The bronchi are the main airways that branch off from the trachea and extend into the lungs. They carry air to and from the lungs, branching further into smaller bronchioles that terminate in the alveoli, where gas exchange occurs.