Answer :
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1. The esophagus is muscular and moveable because its primary function is to transport food from the mouth to the stomach through a process called peristalsis. Peristalsis is the wave-like muscle contractions that push food down the esophagus. The muscular walls of the esophagus allow it to contract and relax, enabling the movement of food without being voluntary.
2. On the other hand, the trachea is hard and unmovable to maintain its structure and prevent collapse during breathing. The trachea needs to stay open at all times to ensure the passage of air into the lungs. If it were soft and moveable, it could collapse easily, obstructing the airflow and causing breathing difficulties.
In summary, the structures of the esophagus and trachea are adapted to their specific functions. The esophagus needs to be muscular and moveable for food transport, while the trachea must remain rigid and unmovable to facilitate uninterrupted airflow during breathing.