Question

The hinder end of male Ascaris is
A. Straight
B. Thickened
C. Coiled
D. Curved

Answer 1

Ascaris lumbricoides is a parasitic nematode found in our small intestine. They are the most common parasites found in human beings, pigs, cattle. They have small and thin males and large and wide females.

Complete answer:
Ascaris lumbricoides is an internal obligate parasite with no free living stages throughout its life cycle. It lives in the small intestines of human beings specifically in the jejunum region. It protects itself from pepsin enzymes that can digest it along with food by secreting pepsin inhibitors. It also takes advantage of the muscular activity to prevent itself from being excreted. They release their eggs loaded into the faecal material from where they pass to the soil and then to plants. Any organism who consumes those plants having eggs of Ascaris will get the infection. The released fertilized eggs require 3 weeks of embryonation in soil before they get infective and after that they can live up to 10 years in the soil when provided with moist and warm conditions.

It is the largest intestinal nematode which produces a disease called Ascariasis. Males and female have distinctive features in them like –
-Females are 25-30 cm in length and 4-6 mm in width, whereas males are 15-22 cm in length and 2-4 mm in diameter. Males are smaller than females.
-Both of them have cylindrical bodies which are tapered at both the ends. The tail is the distinctive feature as males have a ventrally curved tail and females have a straight tail.
-Females have vulva opening which is present on the ventral side of the body and males have papillae which are grouped pre and post anally.
-Males have spike-like pineal extensions near the posterior opening which are not present in females.
-Females have two reproductive tubes that join and form a Y like structure whereas male have only one reproductive tube.

Hence, the correct answer is option (D).

Note: Three forms of eggs are produced by them – fertilized golden brown, oval eggs, decorticated which don’t have external mammillated layer and are thick and unfertilized eggs which are elongated in structure and much larger than the other eggs, but they are unorganised internally and have a thin outer layer.