Respiration Quiz - CBSE Class 12 Biology

Free practice quiz: Respiration (CBSE Class 12 Biology). 11 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following is the primary site of gas exchange in the human respiratory system?

   1. Trachea
   2. Bronchi
   3. Alveoli
   4. Larynx
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   Answer: C. Alveoli

   Alveoli are tiny air sacs in the lungs where oxygen from inhaled air diffuses into the blood and carbon dioxide from the blood diffuses into the air to be exhaled.

2. What is the approximate volume of air inhaled or exhaled in one breath during normal breathing?

   1. 500 ml
   2. 1500 ml
   3. 2500 ml
   4. 3500 ml
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   Answer: A. 500 ml

   This volume is known as tidal volume.

3. What is the Bohr effect?

   1. Increased pH reduces hemoglobin's affinity for oxygen
   2. Decreased pH reduces hemoglobin's affinity for oxygen
   3. Increased pH increases hemoglobin's affinity for oxygen
   4. Decreased pH increases hemoglobin's affinity for oxygen
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   Answer: B. Decreased pH reduces hemoglobin's affinity for oxygen

   The Bohr effect describes how a decrease in blood pH (increased acidity) reduces hemoglobin's affinity for oxygen, promoting oxygen release in tissues.

4. Explain the differences between internal and external respiration.

   1. They are the same process
   2. Internal respiration is gas exchange in lungs and external is gas exchange in tissues
   3. Internal respiration is gas exchange in tissues and external is gas exchange in lungs
   4. Internal respiration is oxygen utilization and external is carbon dioxide removal
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   Answer: C. Internal respiration is gas exchange in tissues and external is gas exchange in lungs

   External respiration is gas exchange between the lungs and blood, while internal respiration is gas exchange between the blood and tissues.

5. Explain the mechanism of hypoxia-induced hyperventilation and its physiological significance.

   1. Hypoxia causes slower breathing
   2. Hypoxia causes no change in breathing
   3. Hypoxia causes increased breathing to compensate for lower oxygen levels
   4. Hypoxia causes decreased breathing to conserve oxygen
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   Answer: C. Hypoxia causes increased breathing to compensate for lower oxygen levels

   Hypoxia (low oxygen levels) triggers hyperventilation (increased breathing rate and depth) to increase oxygen uptake and compensate for the low oxygen levels.

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