Free Human Respiratory System MCQs with Answers
146 Human Respiratory System MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The human respiratory system conducts air to the alveoli, where oxygen and carbon dioxide exchange occurs across thin respiratory surfaces. Questions cover the nasal passage, trachea, bronchi, lungs, diaphragm and intercostal muscles, ventilation mechanics and gas transport, while distinguishing breathing and gaseous exchange from cellular respiration.
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146 questions · page 7 of 8
121. Which one of following factors is directly proportional to oxygen carrying capacity of haemoglobin:
- A. Carbon dioxide
- B. Temperature
- C. pH
- D. Light
Explanation: Option [A] the greater the carbon dioxide the lesser the capacity to carry oxygen, as Co2 increases more H+ ions are produced in…
Correct answer: pH- A. Contraction of lungs
- B. Contraction of intercostal membrane
- C. Relaxation of intercostal and diaphragm muscles
- D. Contraction of diaphragm muscles
Explanation: Option [a] Lungs do not contractOption[b] Internal intercostal muscles contractOption [c] During expiration External intercostal muscles…
Correct answer: Relaxation of intercostal and diaphragm muscles- A. 6.7 litres
- B. 2.5 litres
- C. 7 litres
- D. 5-6 litres
Explanation: In an adult human being when the lungs are fully inflated the total inside capacity of lungs is about 5-6 litres.
Correct answer: 5-6 litres- A. Amino group of haemoglobin
- B. Iron is part of haemoglobin
- C. heme portion of haemoglobin
- D. Plasma proteins
Explanation: Carbaminohemoglobin is a stable complex of carbon dioxide and hemoglobin that forms in red blood cells upon contact with carbon dioxide.
Correct answer: Amino group of haemoglobin- A. 1.2 cm
- B. 1 cm
- C. 1 mm
- D. 1.2 mm
Explanation: When the smaller bronchi attain a diameter of one mm or less, then they are called bronchioles.
Correct answer: 1 mm- A. Respiratory distress syndrome
- B. Emphysema
- C. Bronchitis
- D. Asthma
Explanation: The key feature of respiratory distress syndrome (RDS) is the insufficient production of surfactant in the lungs.Emphysema is a lung…
Correct answer: Respiratory distress syndrome- A. Inspiration is an active process
- B. Expiration is a passive process
- C. Inspiration is a passive process
- D. Both expiration and inspiration are passive processes
Explanation: Inspiration is an active process because it involves the contraction of the diaphragm and intercostal muscles, which results in the…
Correct answer: Inspiration is an active process- A. Trachea
- B. Bronchi
- C. Bronchioles
- D. Alveoli
Explanation: Bronchi are larger airway passages in the respiratory system, and they are primarily lined with cartilage for structural support.
Correct answer: Alveoli- A. 5-6 liter.
- B. 8-9 liter
- C. 10-11 liter
- D. 12-13 liter
Explanation: The normal lung capacity of an average adult human is about 5 to 6 liters.
Correct answer: 5-6 liter.- A. Chest wall is raised and diaghram is lowered
- B. Chest wall is raised and diaghram is also raised
- C. Chest wall is lowered and diaghram is raised
- D. Chest wall is lowered and diaghram is also lowered
Explanation: Ok we will go through inspiration and expiration on a conceptual basis During inspiration, air moves in the lungs, so atmospheric pressure…
Correct answer: Chest wall is raised and diaghram is lowered- A. Fibrous
- B. Hyaline
- C. Elastic
- D. Neurotic
Explanation: Hyaline cartilage is found at the ends of long bones and in the nose at the larynx and trachea.
Correct answer: Hyaline- A. Digestive
- B. Circulatory
- C. Respiratory
- D. Excretory
Explanation: Instead of nostrils, grasshoppers breathe through openings in the thorax and abdomen called spiracles.
Correct answer: Respiratory- A. Fishes
- B. Amphibians
- C. Birds
- D. Mammals
Explanation: Alveoli, small air sacs in the lungs where gas exchange occurs, are present in fishes.
Correct answer: Fishes- A. Birds
- B. Crocodiles
- C. Fishes
- D. Toads
Explanation: Correct Answer: BirdsThe presence of a diaphragm in birds allows for effective respiration by assisting in lung function.
Correct answer: Birds- A. Birds
- B. Crocodiles
- C. Fishes
- D. Toads
Explanation: Mammals are characterized by a well-developed diaphragm that separates the thoracic chamber from the abdominal cavity.
Correct answer: Crocodiles- A. The cardiac center
- B. Ventilation center
- C. Pons
- D. Carotid sinus
Explanation: The rhythmicity of respiration is primarily maintained by the respiratory centers located in the pons region of the brainstem.
Correct answer: Pons- A. 44 times/minute
- B. 40 times/minute
- C. 25 times/minute
- D. 20 times/minute
Explanation: The breathing rate decreases with age. Some average breathing rates are given below: 2-5 years= 25-30 breaths/min 5-12 years= 20 to 25…
Correct answer: 25 times/minute- A. Trachea
- B. Bronchus
- C. Bronchioles
- D. Tracheoles
Explanation: The correct answer is Bronchioles. Bronchioles do not contain cartilage, unlike the trachea and bronchi, which have cartilage to maintain…
Correct answer: Bronchioles- A. 19.4 ml
- B. 19.6 ml
- C. 20 ml
- D. 21 ml
Explanation: In 100 ml of blood, there is about 15 g of hemoglobin, which can bind approximately 20.1 ml of oxygen.
Correct answer: 20 ml- A. 77%
- B. 90%
- C. 87%
- D. 97%
Explanation: Red blood cells (also known as erythrocytes) contain a protein called hemoglobin, which carries oxygen from the lungs to all parts of the…
Correct answer: 97%