Breathing and exchange of gases MCQs

By: Prof. Dr. Fazal Rehman Shamil | Last updated: February 5, 2025

  1. Which of the following structures is responsible for the exchange of gases in the human body?
    a) Lungs
    b) Trachea
    c) Alveoli
    d) Bronchi
    ✔️ Answer: c) Alveoli
  2. Which of the following is the main component of air that is utilized by humans during breathing?
    a) Nitrogen
    b) Oxygen
    c) Carbon Dioxide
    d) Water vapor
    ✔️ Answer: b) Oxygen
  3. What is the process by which oxygen from the lungs enters the bloodstream?
    a) Inhalation
    b) Exhalation
    c) Diffusion
    d) Filtration
    ✔️ Answer: c) Diffusion
  4. Which of the following gases is mainly expelled during exhalation?
    a) Oxygen
    b) Nitrogen
    c) Carbon dioxide
    d) Hydrogen
    ✔️ Answer: c) Carbon dioxide
  5. In which part of the brain is the control center for breathing located?
    a) Cerebellum
    b) Medulla oblongata
    c) Pons
    d) Thalamus
    ✔️ Answer: b) Medulla oblongata
  6. Which of the following occurs during inhalation?
    a) The diaphragm relaxes and moves upward
    b) The chest cavity decreases in volume
    c) The ribs move downward
    d) The diaphragm contracts and moves downward
    ✔️ Answer: d) The diaphragm contracts and moves downward
  7. What is the function of the hemoglobin in the red blood cells?
    a) To carry oxygen from the lungs to the tissues
    b) To transport nutrients to the tissues
    c) To remove carbon dioxide from the blood
    d) To fight infections
    ✔️ Answer: a) To carry oxygen from the lungs to the tissues
  8. The process by which oxygen and carbon dioxide are exchanged between the blood and alveoli is called:
    a) Respiration
    b) Diffusion
    c) Ventilation
    d) Circulation
    ✔️ Answer: b) Diffusion
  9. Which of the following is a waste product produced during cellular respiration?
    a) Oxygen
    b) Nitrogen
    c) Carbon dioxide
    d) Glucose
    ✔️ Answer: c) Carbon dioxide
  10. The main function of the respiratory system is to:
    a) Circulate blood throughout the body
    b) Bring oxygen into the body and expel carbon dioxide
    c) Digest food
    d) Maintain body temperature
    ✔️ Answer: b) Bring oxygen into the body and expel carbon dioxide
  11. Which of the following occurs during exhalation?
    a) The diaphragm contracts
    b) The chest cavity expands
    c) The diaphragm relaxes and moves upward
    d) The intercostal muscles relax
    ✔️ Answer: c) The diaphragm relaxes and moves upward
  12. The process of exchanging gases between the atmosphere and the blood is called:
    a) External respiration
    b) Internal respiration
    c) Cellular respiration
    d) Diffusion
    ✔️ Answer: a) External respiration
  13. The gas that stimulates the breathing center is:
    a) Oxygen
    b) Carbon dioxide
    c) Nitrogen
    d) Hydrogen
    ✔️ Answer: b) Carbon dioxide
  14. What is the primary reason for breathing?
    a) To get rid of excess nitrogen
    b) To supply the body with oxygen
    c) To regulate the body temperature
    d) To excrete wastes from the body
    ✔️ Answer: b) To supply the body with oxygen
  15. Which of the following is a part of the lower respiratory tract?
    a) Nasal cavity
    b) Trachea
    c) Pharynx
    d) Larynx
    ✔️ Answer: b) Trachea