CBSE Class 11-science Answered

Cockroaches belong to the class Insecta of the phylum Arthropoda.

The scientific name for cockroach is Periplaneta americana.

The length of an adult Periplaneta americana is 34–53 mm.

The body of a cockroach is segmented into the head, thorax and abdomen.

Sclerites are the hard chitinous plates which form the exoskeleton in cockroach.

Tergites cover the body of cockroach ventrally while sternites cover the body of cockroach dorsally.

Antennae in cockroaches have sensory receptors which help in monitoring the environment.

The mouthparts found in cockroach are a labrum, a pair of mandibles, a pair of maxillae and a labium.

Alimentary canal:

Alimentary canal divides the body of a cockroach into foregut, mid gut and hindgut.

Mouth opens into crop which is used for storing the food.

Crop is followed by the gizzard. It helps in grinding the food.

Gastric caecae present at the junction of foregut and mid gut secrete digestive juices.

Hind gut is differentiated into ileum, colon and rectum.

Rectum opens out through anus.

Excretory system:

100–150 Malpighian tubules are present in cockroach.

They are present at the junction of mid gut and hind gut.

Uric acid is the waste product formed at the end of the process. Hence cockroaches are uricotelic animals.

Circulatory system:

The heart of a cockroach is a long muscular tube lying along the mid-dorsal line of the thorax and abdomen.

It is differentiated into funnel-shaped chambers, and it bears ostia on either side.

Blood from the sinuses enters the heart through ostia, and it moves anteriorly in the heart and is released into the sinuses again.

Respiratory system:

The respiratory system of cockroach consists of a network of tracheae.

Tracheae open outside through 10 pairs of spiracles which are present on the lateral side of the body.

Tracheae are further divided into tracheoles which carry oxygen to all parts of the body. Exchange of gases occurs at the tracheoles by diffusion.

The openings of spiracles are regulated by the sphincters.

Male Reproductive System:

A pair of testes lying on the lateral sides of 4-6 abdominal segments.

From each testis, a thin vas deferens arise which opens into an ejaculatory duct through seminal vesicle.

Ejaculatory duct open into the male gonophore.

Phallomere represents the external genitalia of the male cockroach.

Female Reproductive System:

Female reproductive system consists of two large ovaries.

Each ovary is formed of eight ovarioles.

Oviducts of both the ovaries unite to form median oviduct.

A pair of spermatheca is present in the 6^th segment which opens into the genital chamber.

Economic importance: