Which of the following statement is/are correct regarding digestive system of cockroach ?

1. Mouth opens into a short tubular pharynx, leading to a narrow tubular passage called oesophagus.
2. Gizzard helps in grinding the food particles.
3. A ring of 6-8 blind tubules called hepatic or gastric caecae is present at the junction of foregut and midgut, which secrete digestive juice.
4. At the junction of midgut and hindgut is present another ring of 100-150 yellow coloured thin filamentous malphigian tubules which help in removal of excretory products from haemolymph.

Correct Answer : D.

Digestive system of cockroach is divided into - foregut, midgut and hindgut. The mouth opens into a short tubular pharynx which further opens into a narrow tubular structure called oesophagus. The oesophagus opens into a sac-like structure called crop where food is stored. The crop is followed by gizzard and proventriculus. The gizzard helps in grinding the food particles. The entire foregut is lined by cuticle. At the junction of foregut and midgut, a ring of 6 - 8 blind tubules are present. These are called gastric or hepatic cecae which secrete digestive juice. The hindgut is broader than the midgut. The hindgut is differentiated into ileum, colon and rectum. The rectum opens through anus. Malpighian tubules are the excretory organs which absorb nitrogenous wastes and convert them into uric acid. Uric acid is excreted out through the hindgut.