Tag: introduction to reproduction

(A) Phallomere - The external genitalia

Sexual dimorphism is the differences in appearance between males and females of the same species. The adult males have full wings covering their body, while females have only tiny wing stubs, their tegmina (forewings) being around a fourth of their body length.
Therefore, the correct answer is option D.

Sex pheromones are released by an organism to attract an individual for mating. Cockroaches form the dominance hierarchies based on pheromone badges, while females use the same pheromone for male choice.
Therefore, the correct answer is option B.

The intersegmental membrane between the 5th and 6th terga is depressed on either side of the stink gland. These glands are present in both male and female cockroaches and produce a secretion with a characteristic odour. The secretion is a pheromone which helps to attract the opposite sex.
Therefore, the correct answer is option C.

Eggs of cockroach are centrolecithal. During cytokinesis, centrolecithal zygotes undergo meroblastic cleavage, where the cleavage plane extends only to the accumulated yolk and is superficial. This is due to the large dense yolk found within centrolecithal eggs and helps in delayed embryonic development.

The colleterial glands open into the vestibulum and secrete most of the protein and tanning agent. The protein may not be directly concerned with ootheca formation, while the latter probably secretes the alkali-resistant outer layer of the ootheca.
The anterior and posterior parts of cockroach secreting the structural protein which produces most of the material used in the formation of the ootheca.

Cockroach eggs hatch because of the combined pressure of the hatchlings within. Upon emerging from the egg case, or ootheca, this immature form of cockroach is known as a nymph or baby cockroach. Nymphs are bright white in color initially. Cockroach nymphs are grayish-brown in color and darken with each progressive molt.  Cockroach nymphs undergo a series of molts. They emerge as full adults from their final molt.

The abdomen is made up of 10 segments. The 7th, 8th and 9th sterna form a genital pouch in females. In males, the genital pouch is present at the hind end of the abdomen. The male cockroach has thread-like anal styles, which are missing in the female cockroach. Hence, Male Cockroach is identified by the presence of anal style.

In cockroaches, the sperm is stored in the seminal vesicles and are glued together in the form of bundles called spermatophores and discharged during copulation. Seminal vesicles are the part of the ejaculatory duct.