Question

Assertion: Tracheae, primary, secondary and tertiary bronchi are supported by incomplete cartilaginous rings.
Reason: These rings of cartilage make the wall non-collapsible.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: In humans, the lungs are the organ of respiration and breathing. The lungs are connected with the larynx through a cartilaginous tube-like structure which is known as the trachea. The trachea is also referred to as the windpipe.

Complete answer:
The trachea extends from the larynx and moves up to the bronchi of the lungs. The bronchi are branched into primary, secondary and tertiary bronchi. It facilitates the passage and movement of air into the lungs. The trachea consists of various numbers of cartilaginous rings. The rings are horseshoe shaped and are incomplete. They are made up of cartilaginous tissues. The rings are joined together with the help of ligaments. The rings encircle the front portion of the trachea and they open where the trachea are present just next to the esophagus.
These cartilages are also known as hyaline cartilage and are 16 to 20 in numbers. They are C shaped and form an incomplete ring structure. The main function of the rings is to support the internal structure of the breathing pipe. The arrangement of the rings allows the stretching of the trachea so that it can stretch and descend while the breathing movements.
 The non-collapsible nature of the rings are formed by the cartilaginous tissues. The cartilaginous rings are further joined by the ligaments which support them. The lower end of the incomplete rings are connected to a muscle that is known as trachealis muscles. The trachealis muscles run along the back wall of the trachea. The inner layer of the rings are made up of mucous membrane and muscle fibres move alongside the cartilage. This arrangement of the rings makes the rings non collapsible and aid in the process of respiration.
Thus, in this particular case, both the assertion and reason are correct. The reason is the correct and appropriate explanation of the assertion.
Thus, the right option is A.

Note: The trachea is the connection between the larynx to that of the bronchi of the lungs. It is also known as the windpipe. The trachea is connected to the primary, secondary as well as tertiary bronchi by incomplete, C shaped like structures which are known as the incomplete rings. They are made up of cartilaginous tissues and are non-collapsible in nature.