Question

Infective stage of Ascaris is
A. Adult worm
B. Second juvenile
C. Fourth juvenile
D. Egg

Answer 1

Hint:-Ascaris is a human intestinal parasite. It is the infection of the most common human worm. In the small intestine, the larvae and adult worms live and can cause intestinal illness. Parasitic worms referred to as soil-transmitted helminths (STH) are Ascaris, hookworm, and whipworm. Together, they account for a significant parasitic disease burden worldwide.

Complete Answer:-The pig roundworm (Ascaris suum) can also infect humans. It is indistinguishable from Ascaris lumbricoides (human roundworm) and Ascaris suum (pig roundworm). Ascaris lives in the gut, and in the faeces of infected individuals, Ascaris eggs are passed around. Eggs are collected on the soil if the infected person defecates outside or if an infected person's faeces are used as fertiliser. Then they will grow into a shape that is infectious. Ascariasis is caused by infected eggs being swallowed.
In the lumen of the small intestine, adult worms live. Up to thousands eggs per day that are passed through the faeces can be produced by a female. Depending on the environmental conditions, fertile eggs become embryonic and become contagious after days to several weeks. The larvae hatch, invade the intestinal mucosa, and are transported through the portal, then systemic circulation to the lungs after infective eggs are swallowed. In the lungs, the larvae develop further, penetrate the alveolar walls, climb to the throat of the bronchial tree and are swallowed. They turn into adult worms when they enter the small intestine. Between months from the ingestion of the infectious eggs to the oviposition of the adult female is needed. Adult worms are capable of surviving for one to two years.
Ascaris is monogenetic since it has only one host, the man directly in whom infection occurs. Spiral, determinate, and holoblastic are cleavage. Few days after cleavage, the first larvalis developed and is called the rhabditiform larva or first larva, which is not an infectious stage. It moults into a second larva in another week, which is capable of infecting the host. By directly ingesting Ascaris eggs along with contaminated food or water, man acquires infection.

Hence, the correct answer is (b) Second Juvenile

Note:- The eggs have a lipid layer which makes them, as well as other chemicals, resistant to the effects of acids and alkalis. This resilience helps to explain why this nematode is a parasite that is so ubiquitous. The vulva is situated at the anterior end and accounts for approximately one third of the length of its body. Uteri can produce up to million eggs at a time.