Question

With reference to external features of Cockroach, which among the following statement is not correct
A.It has pulvillus between claws
B.Hind wings are protective and are not useful in flight
C.Fore wings are elytra
D.Gonapophysis help in copulation

Answer 1

Hint: Periplaneta americana is the common species of cockroach. An adult cockroach is about 34 – 53 mm long. Wings extend beyond the tip of the abdomen in males. The body is segmented into three distinct regions, viz. head, thorax and abdomen.

Complete answer:
Cockroaches also called roaches are one of the most primitive living winged insects. They possess flat-oval body, antennae, shining black/brown leathery integument. Their head is bent downwards and mouthparts point backward. Male cockroaches have two pairs of wings, while females are sometimes wingless or possess vestigial wings.
Cockroaches commonly inhabit damp and warm places. They are mostly found in kitchens, hotels, bakeries, restaurants, etc. They are nocturnal and omnivorous. They are dioecious, oviparous and exhibit parental care.

External features:
The body is elongated and segmented and dark brown in colour.
The exoskeleton is thick, hard made from calcareous plates called sclerites. Exoskeleton is coated with wax impermeable to water which protects body from loss of water and provides rigidity and surface for attachment of body muscles.
The adjacent segments are joined by a thin, soft and versatile arthrodial membrane.
They possess three pairs of jointed appendages and two pairs of wings.
The fore wings are mesothoracic and are called wing covers or tegmina or elytra. They cover the hindwings which are protective in function.
The hind wings are large, thin, membranous and transparent. they're kept folded below the tegmina and are used for flying.

Hence, the correct answer is option (B)

Note: They have three endocrine glands, out of which two are related to ecdysis and growth. Before each moult a neurosecretory hormone from the inter-cerebral gland cells of the brain (brain or prothoracicotropic hormone) stimulates prothoracic glands to release a hormone ecdysone or moulting hormone into the hemolymph which induces growth and moulting. This hormone also stimulates body tissues to grow and differentiate towards adulthood.