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.

This CBSE Class 12 Biology practice quiz has 11 multiple-choice questions on Respiration, and 11 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz 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
   Show answer

   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
   Show answer

   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
   Show answer

   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
   Show answer

   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.

More questions in this quiz

Answers and explanations are in the full quiz.

1. What is the role of surfactant in the alveoli?
2. Explain the role of hemoglobin in oxygen transport.
3. How does the respiratory system regulate blood pH?
4. Discuss the role of the respiratory centers in the brainstem in regulating breathing.
5. What is the difference between vital capacity and total lung capacity?
6. How does the partial pressure of oxygen (PO2) and carbon dioxide (PCO2) influence gas exchange in the alveoli?

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