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Respiration MCQs for MDCAT Practice

Biology section, Respiration chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 973 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    It transports oxygen from the lungs to every tissue of the body.
    • Hemoglobin (correct answer)
    • Proteins
    • Hormones
    • Lipids
    • Antibodies
    Correct answer: A
    Hemoglobin is the primary protein responsible for transporting oxygen from the lungs to tissues throughout the body.
  2. Question 2
    Considering the functional anatomy, damage to the ciliated epithelium in the initial parts of the air passage would most directly impair:
    • The exchange of gases at the alveolar surface.
    • The maintenance of the airway's structural rigidity.
    • The warming and moistening of inhaled air.
    • The clearance of trapped dust and pathogens from the airway lining. (correct answer)
    Correct answer: D
    Ciliated epithelium in the upper airways is crucial for mucociliary clearance, trapping and removing inhaled particles and pathogens.
  3. Question 3
    Large dust particles are trapped in human nostrils by which of the following:
    • Bone
    • Hairs
    • Mucus
    • Both B and C (correct answer)
    Correct answer: D
    Nostril hairs and mucus work together to trap inhaled dust particles, preventing them from reaching the lungs.
  4. Question 4
    Which one of the following acts as functional unit of lungs in man?
    • Air sac (correct answer)
    • Trachea
    • Larynx
    • Bronchioles
    Correct answer: A
    The air sacs (alveoli) are the functional units of the lungs, responsible for gas exchange via diffusion.
  5. Question 5
    People who migrated from plains to hills six months back _______________.
    • Possess more RBCs with haemoglobin of low O2 binding affinity (correct answer)
    • Possess same RBCs with haemoglobin of high O2 binding affinity
    • Lose physical fitness to play games like football
    • Suffer from altitude sickness with nausea and fatigue
    Correct answer: A
    After 6 months at high altitude, migrants adapt via increased RBC count and elevated 2,3-BPG, which shifts the Hb-O₂ dissociation curve rightward — lowering O₂ affinity to improve tissue unloading.
  6. Question 6
    How moderate grazing is helpful for ecosystem?
    • It increases soil erosion and reduces biodiversity. (correct answer)
    • It reduces competition among plant species and improves water infiltration.
    • It increases plant diversity and soil fertility.
    • It decreases plant growth and nutrient cycling.
    Correct answer: A
    Moderate grazing can enhance plant diversity and productivity by preventing the dominance of a few species and cycling nutrients, benefiting the ecosystem.
  7. Question 7
    Mechanical process which consists of two phases inspiration and expiration is called:
    • Respiration
    • Breathing (correct answer)
    • Photosynthesis
    • Translocation
    Correct answer: B
    Breathing (inspiration & expiration) is the mechanical act of gas exchange, distinct from respiration (cellular O2 use). Photosynthesis and translocation are unrelated biological processes.
  8. Question 8
    Lungs are porous due to the presence of:
    • Bronchi
    • Alveoli (correct answer)
    • Terminal bronchiole
    • Respiratory bronchiole
    Correct answer: B
    The lungs' porous structure, essential for gas exchange, is primarily due to the vast number of alveoli, tiny air sacs where oxygen and carbon dioxide transfer occurs.

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