Q. Which of the following mouth parts of cockroach are unpaired?

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Solution:

The anterior end of the head of cockroach bears appendages forming biting and chewing type of mouth part. It consists of labrum, a pair of mandible, a pair of maxillae and a labium. Within the cavity enclosed by the mouth parts, a median flexible lobe acting as tongue (hypopharynx) is present. "Labium"or lower lip (Fused 2nd maxillae)
l Form floor of preoral cavity (Ventral side) and provides a platform for food materials.
(5) Hypopharynx :- or "lingua"
l Small, non-chitinous flexible structure that lies on the floor of preoral cavity.
l It bears several sensory setae at its free end, and the common salivary duct opens at the base of hypopharynx,
threrefore it is also considered as tongue of cockroach.