Question:

Third moulting in the life cycle of Ascaris takes ^ place in

Updated On: Jul 27, 2022
  • soil
  • water
  • lungs
  • intestine
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The Correct Option is C

Solution and Explanation

Ascaris belongs to a group of organisms called helminthes or worms (roundworms). It is an endoparasite of small intestine of human beings. It is more common in children. This parasites have a direct life cycle with no intermediate hosts. Third moulting in the life cycle of Ascaris takes place in lungs (alveoli). In intestine through trachea 4th stage larva Young Ascaris Embryonated eggs being swallowed in contaminated food or drink 4th stage larva Intestine Adult male Ascaris 3rd stage larva In lung through pulmonary artery In heart through postcaval vein Egg capsules Anus In liver through hepatic portal vein Egg capsule in faeces For its close resemblance with the nematode genus Rhabditis, found in soil and human faeces, the juvenile is also termed rhabditoid or rhabditiform larva offirst stage. It is not infective. In another week?? time, it moults within the egg shell and becomes the second stage rhabditoid, which is capaple of infecting the host. Man acquires infection by directly ingesting Ascaris eggs, containing the infective second stage rhabditoid larva, with contaminated food or water. In the small intestine, by the action of host?? digestive juices, the egg shells dissolve and the juveniles (second stage larvae) hatch out and performs active thrashing movements and bores through the epithelium of host?? intestine and starts its migration in host?? body. Larva enters the hepatic portal circulation which carries it to the liver and it finally reaches the heart through post-caval vein. From heart it is transported to the lung via pulmonary artery. After about 6 day?? stay in alveoli, the second stage larva moults to become the third stage larva. Another moult after 4 days results in the fourth stage larva. In the intestine, it moults for the fourth and the last time to become an adult. Adult attains sexual maturity within 8-10 weeks.The average life-span of Ascaris lumbricoides in the host is 9 - 12 months.
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Notes on Classification Of Animals

Concepts Used:

Classification of Animals

Classification of Animal Kingdom:

One of the most fundamental forms of classification of animals is the presence or absence of the notochord. Hence, two major groups exist, namely: Chordates and Non-chordates

Non-chordates and the Chordates-

  • The notochord is a flexible rod made out of a material similar to cartilage. If an animal has a notochord during any stage of its life, it is classified as a chordate. Contrary to popular belief, chordates do not exclusively include vertebrates.
  • There are invertebrates that possess a notochord during some point in their lives and hence, are classified as chordates. Thus all vertebrates are chordates but not all chordates are vertebrates.

Non-chordates-

  • Non-chordates are animals without a notochord – the rod-like elastic structure that supports the body. This phylum consists of a small group of worm-like, marine species with an organ-system level of organization.
  • Members of phylum Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata fall under Non-chordates

Vertebrates Classification:

The subphylum Vertebrata is divided into five classes of vertebrates. These five classes of vertebrates comprise of all the species of animals and have developed vertebral column as well as an internal skeleton.

Other characteristic features of vertebrates are-

  • Presence of a true vertebral column and internal skeleton with muscle attachment points for body movement.
  • A front-side muscular heart with two, three or four chambers.
  • Kidneys for excretion and osmoregulation
  • A paired appendages which may be fins or limbs.
  • Possess notochord during the embryonic stage.
  • Vertebrates are the only chordates to possess a brain as a part of the central nervous system.

Classification of Vertebrates-

  • Pisces
  • Amphibia
  • Reptilia
  • Aves
  • Mammalia