Questions on Breathing: mechanisms, regulation, and related concepts
Multiple-Choice Questions: Breathing
1. What is the process of taking air into the lungs called?
A) Exhalation
B) Respiration
C) Inhalation
D) Circulation
E) Photosynthesis
2. Which muscle plays a key role in the breathing process by contracting and relaxing?
A) Deltoid
B) Diaphragm
C) Biceps
D) Pectoral
E) Trapezius
3. What happens to the diaphragm during inhalation?
A) Relaxes and moves upward
B) Contracts and flattens
C) Contracts and curves upward
D) Becomes inactive
E) Is pushed by the heart
4. Which gas stimulates the brain to increase the breathing rate?
A) Oxygen
B) Nitrogen
C) Carbon monoxide
D) Carbon dioxide
E) Helium
5. What is the scientific term for breathing?
A) Inhalation
B) Respiration
C) Ventilation
D) Circulation
E) Diffusion
6. Which of the following structures helps protect the lungs during breathing?
A) Kidneys
B) Ribs
C) Pelvis
D) Femur
E) Skull
7. Breathing is primarily controlled by which part of the brain?
A) Cerebellum
B) Cerebrum
C) Medulla oblongata
D) Hypothalamus
E) Thalamus
8. What happens to the chest cavity during inhalation?
A) It contracts and shrinks
B) It collapses
C) It expands
D) It becomes rigid
E) It remains unchanged
9. During exhalation, the diaphragm:
A) Contracts and lowers
B) Contracts and expands
C) Relaxes and rises
D) Thickens and stretches
E) Splits in two
10. What is the correct path air follows to reach the lungs?
A) Nose → Pharynx → Larynx → Trachea → Bronchi
B) Nose → Esophagus → Bronchi → Lungs
C) Mouth → Larynx → Stomach → Alveoli
D) Nose → Trachea → Bronchi → Liver
E) Nose → Bronchi → Diaphragm
11. Which of the following terms refers to the amount of air taken in and out during normal breathing?
A) Vital capacity
B) Residual volume
C) Tidal volume
D) Expiratory reserve
E) Inspiratory reserve
12. How does breathing help in cellular respiration?
A) Produces energy directly
B) Filters oxygen
C) Supplies oxygen and removes carbon dioxide
D) Increases glucose
E) Activates enzymes
13. What is the role of intercostal muscles in breathing?
A) Regulate heartbeat
B) Expand and contract the rib cage
C) Pump blood
D) Secrete mucus
E) Support digestion
14. Which of these increases when you hold your breath for a long time?
A) Blood pH
B) Oxygen concentration
C) Lung elasticity
D) Carbon dioxide concentration
E) White blood cell count
15. Which of the following occurs during exhalation?
A) Lung volume increases
B) Air pressure inside lungs drops
C) Rib cage expands
D) Diaphragm contracts
E) Air is pushed out of the lungs
16. What is the breathing rate of an average adult at rest?
A) 4–8 breaths per minute
B) 8–12 breaths per minute
C) 12–20 breaths per minute
D) 20–28 breaths per minute
E) Over 30 breaths per minute
17. The exchange of gases in the lungs occurs in the:
A) Trachea
B) Bronchi
C) Alveoli
D) Pleura
E) Bronchioles
18. What does an increase in carbon dioxide in the blood trigger?
A) Decreased respiratory rate
B) Increased oxygen storage
C) Reduced blood flow
D) Increased respiratory rate
E) Lower lung pressure
19. What is the main reason we breathe faster during exercise?
A) To increase heart rate
B) To improve muscle growth
C) To eliminate more carbon dioxide and bring in more oxygen
D) To digest food faster
E) To warm the lungs
20. Which of the following best defines external respiration?
A) Use of oxygen by cells
B) Breathing in air
C) Gas exchange between alveoli and blood
D) Muscle contraction
E) Movement of food through esophagus
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Answers with Explanations
1. C – Inhalation refers to drawing air into the lungs.
2. B – The diaphragm is the primary breathing muscle.
3. B – The diaphragm contracts and flattens, increasing lung volume.
4. D – High CO₂ levels signal the brain to increase breathing.
5. C – "Ventilation" is the technical term for the act of breathing.
6. B – The rib cage protects the lungs and aids breathing.
7. C – The medulla oblongata controls automatic breathing.
8. C – The chest cavity expands during inhalation.
9. C – The diaphragm relaxes and moves upward during exhalation.
10. A – This is the correct sequence of air passage.
11. C – Tidal volume is the air exchanged in normal breathing.
12. C – Breathing provides oxygen for and removes CO₂ from cells.
13. B – Intercostal muscles move the ribs during breathing.
14. D – CO₂ builds up if you hold your breath.
15. E – Exhalation involves forcing air out of the lungs.
16. C – Normal adult breathing rate is 12–20 breaths/minute.
17. C – Gas exchange occurs in the alveoli.
18. D – High CO₂ triggers increased breathing to expel it.
19. C – Faster breathing during exercise supplies oxygen and removes CO₂.
20. C – External respiration is gas exchange between air and blood.
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