Final answer:
The abnormal development of the first pharyngeal arch can produce defects in the mouth, such as cleft palate.
Step-by-step explanation:
The abnormal development of the first pharyngeal arch can produce defects in the Mouth. One such defect is cleft palate, which affects the hard palate. The hard palate is the bony structure that separates the nasal cavity from the oral cavity and is formed during embryonic development. In severe cases of cleft palate, the bony gap can continue into the anterior upper jaw, resulting in a cleft lip as well.