Question

Anus in Cockroaches occurs on
A. Tenth sternum
B. Dorsal surface of 10th tergum
C. Ventral surface of 10th tergum
D. Ninth sternum

Answer 1

Hint: The anus is the opening through which the gastrointestinal canal ends and exits outside the body. Through the anus, the organisms remove their digestive waste. In organisms the process of food digestion starts in the stomach as it is treated by the digestive enzyme produced by the gastric caeca. The body absorbs required nourishments and the unwanted or undigested material is discharged through the anus.

Complete answer:
The body of a cockroach is divisible into three distinct regions which are the head, thorax, and abdomen.

In cockroach, the alimentary canal is divided into three parts, which are the foregut, midgut, and hindgut. The alimentary canal starts with the foregut which comprises the mouth which leads into a pharynx which in turn falls into a narrow passage which is known as the oesophagus. The oesophagus opens into a sac-like structure called a crop. Food is stored in the crop. It is followed by gizzard and proventriculus.

A cuticle lines the entire foregut. Midgut creates real gut viz. The midgut or mesenteron is about one-third middle part of the alimentary canal. The midgut is a short, tubular structure and it is lined with glandular endoderm. At the anterior end of the midgut, there are eight blind glandular hepatic caeca. The last part of the alimentary canal is the hindgut. It is a coiled structure. The hindgut consists of three parts which are anterior ileum, middle colon, and posterior rectum. The hindgut is broader than the midgut.

There are some long tubules known as Malpighian tubules at the junction of midgut and hindgut. They function to remove the excretory products from the body. The rectum opens to the exterior of the body through the opening called the anus.

The abdomen consists of ten segments. In females, three sterna namely, the seventh, eighth and ninth sterna form a genital pouch. Whereas, in male cockroaches, the hind end of the abdomen bears the genital pouch. In the male cockroach thread-like anal styles are present which are not found in the female cockroach. In both male and female cockroaches, the tenth segment contains a filamentous structure called the anal cerci.

Hence, the correct answer is option (C).

Note: The three main body parts in cockroaches are the head, thorax, and abdomen. The abdomen of a cockroach is divided into a total of ten segments. In both male and female cockroaches, end part of the alimentary canal is opened through a filamentous structure, which is called the anal cerci.