Question

Which of the following are pseudocoelomate? (a) Roundworm (b) Hookworm (c) Filarial worm (d) All of these

Short answer

All of the listed organisms (roundworms, hookworms, and filarial worms) are pseudocoelomates.

Step-by-step solution

Identify the Characteristics of a Pseudocoelomate

First, review what it means for an organism to be a pseudocoelomate. Pseudocoelomates are organisms that have a body cavity called a pseudocoelom, which is only partially lined by mesoderm.

Examine Each Species Individually

Next, examine the organisms listed in the exercise options: roundworms, hookworms, and filarial worms. All three of these organisms are types of nematodes, a phylum of pseudocoelomate organisms.

Confirm that All Options are of the Same Phylum

Finally, check once more to confirm that all the organisms listed are indeed nematodes. If they are, then it can be deduced that they must all be pseudocoelomates.

Key concepts

Nematodes

Nematodes, commonly known as roundworms, are a diverse phylum of organisms that play a crucial role in various ecosystems, as well as in agriculture and human health. Featuring a simple structural design, these worm-like creatures have a tubular digestive system that runs from the mouth to the anus. One of the most distinctive characteristics of nematodes is their pseudocoelom, a fluid-filled body cavity that lies between the digestive tract and the outer body wall.

This cavity is not entirely lined with tissue from the mesoderm layer, unlike true coeloms in other organisms. It serves as a hydrostatic skeleton, giving the worms a flexible yet sturdy structure that aids in movement and distributing nutrients. Notably, nematodes can be free-living or parasitic; the latter can affect humans, animals, and plants, causing various diseases. Familiar examples of parasitic nematodes include the hookworm and the filarial worm, the causative agent of diseases such as elephantiasis.

Phylum of pseudocoelomate organisms

Pseudocoelomates are a unique group of animals within the animal kingdom. They possess a pseudocoelom, which is essentially a body cavity that originates from the blastula's blastocoel, rather than a true coelom that arises entirely surrounded by mesodermal tissue. Pseudocoelomates are classified within the phylum Nematoda, but there are several other phyla such as Rotifera and Acanthocephala that also exhibit this attribute.

The presence of a pseudocoelom has important implications for the physiology of these animals. It allows for a simpler circulation of fluids within the body, providing a means for distributing nutrients and waste products. The fact that such a cavity is only partially lined by mesoderm distinguishes pseudocoelomates from true coelomates, where the cavity is fully lined. This distinction is not merely academic—it relates to developmental patterns and the structural organization of these organisms.

Biology for NEET

The National Eligibility cum Entrance Test (NEET) is an important examination for students in India aspiring to pursue medical and dental undergraduate courses. Biology is a crucial part of the NEET syllabus, as it accounts for half of the question paper. Within biology, understanding the diversity of life, including the phylum Nematoda, is essential.

Candidates are expected to familiarize themselves with various life forms, their classifications, and body structures. For nematodes, recognizing their pseudocoelomate nature is important for several questions related to animal taxonomy and physiology. NEET aspirants should be able to distinguish between different levels of body organization among animals, their life cycles, and their impacts on human health, all of which could be potential examination topics. A solid grounding in the concepts of pseudocoelomates ensures a comprehensive preparation for any questions biology may pose in the NEET examinations.