Question

Ascaris is a specialised and not a degenerated parasite as it is
A. With a straight alimentary canal
B. Dioecious
C. Without respiratory organ
D. Covered by cuticle resistant to digestive juices of host

Answer 1

Hint: Ascaris lumbricoides, commonly known as Ascaris, is an intestinal parasite. This roundworm resides in the small intestine and causes a disease known as Ascariasis. These parasites possess certain adaptive features that help them against the harsh environment of the digestive system.

Complete answer:
So, Ascaris is a specialized and not a degenerated parasite as it is covered by a cuticle that is resistant to the digestive juices of the host. This thick cuticle also provides resistance against the antitoxins of the host.
Additionally, the Ascaris also secretes a few anti-enzymes against the enzymes of the digestive tract.

The correct answer is option ( D ) that is Covered by cuticle resistant to digestive juices of host.

Additional information:
Some of the other parasitic adaptations of Ascaris lumbricoides are:
The mouth is made up of three lips that facilitate the attachment of the worm to the mucous membranes of the tract.
A muscular pharynx helps in digesting the food through a sucking action.
There is no storage organ due to the abundance of food at all times.
Anaerobic respiration helps these worms to survive in the intestines where there is no free oxygen.
The eggs are minute and covered by a chitinous shell that protects them against the harsh environment of the digestive system. The small-sized eggs even facilitate the widespread distribution of the parasite.

Note: Ascariasis is an intestinal infection that is caused by the ingestion of the eggs of Ascaris lumbricoides. The eggs are found either in contaminated soil or in uncooked food that is contaminated by soil. Mostly, the infections are not serious, however, heavy infestations can lead to complications like intestinal blockage, duct blockage, and nutrient deficiency.