Question

What closes at the time of swallowing to protect the respiratory tract from food particles?

Answer 1

Food must enter the food pipe, not in the wind pipe/trachea. Both the pipes open in pharynx. During swallowing, a cartilagenous flap called epiglottis closes the entrance of wind pipe.

Explanation:

Epiglottis prevents choking of wind pipe by preventing food from entering in the wind pipe during swallowing. Closure of glottis by epiglottis is a reflex action.