Question

Assertion (A) In normal breathing, inspiration is an active process.
Reason (R) Inspiration is facilitated by contraction of diaphragm and external intercostal muscles.

• A. If both A and R are true and R is the correct explanation of A
• B. If both A and R are true, but R is not the correct explanation of A
• C. If A is true, but R is false
• D. If A is false, but R is true

Answer 1

Answer: (B)

Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
Inspiration is an active process whereas expiration is a passive process. During inspiration, diaphragm and external intercostal muscles contract to increase the overall volume of the thoracic cavity. As a result, the pressure inside the lungs is less as compared to atmospheric pressure. Also, for this inspiration muscle uses energy for contraction, thus it is referred to as an active process.