Test: Ascaris - 1 (Old NCERT) - NEET MCQ

They have a pseudocoelom, where the body cavity is not lined by the mesodermal layer. The body cavity of phylum Aschelminthes is called pseudocoelom. It is filled with pseudocoelomic fluid. The body cavity is not lined by the mesodermal layer.

Dorsal, ventral and lateral longitudinal nerves arise from the brain and extend posteriorly in the epidermal cords. A small lateral nerve cord is present in each lateral epidermal cord. Ascaris has no amphids.

A muscle fiber is composed of many fibrils, packaged into orderly units. The striated appearance of skeletal muscle tissue is a result of repeating bands of the Non contractile proteins actin and myosin that are present along the length of myofibrils. Myofibrils are composed of smaller structures called myofilaments.

Saprozoic nutrition is the mode of nutrition of an animal by absorption of dissolved salts and simple organic nutrients from surrounding medium and species of Ascaris infect intestine of various mammals including humans, also referred to as round worm and cause a disease known Ascariasis, get their nutrition from absorbing the nutrients from their surroundings

Skeletal muscle tissue is composed of cells called muscle fibers. When the nervous system signal reaches the neuromuscular junction a chemical message is released by the motor neuron. The chemical message, a neurotransmitter called acetylcholine, binds to receptors on the outside of the muscle fiber.

Ascaris is an intestinal parasite of humans. It is the most common human worm infection. The larvae and adult worms live in the small intestine and can cause intestinal disease.

Ascaris belongs to the phylum aschelminthes. Digestion in aschelminthes is extracellular therefore digestion in ascaris will also be extracellular.

In ascaris, each pineal sac contains a needle like penial structure, composed of chitin, called pineal setae.

The lateral ganglia are taken to be composed of those cell bodies, including the amphidial cells, in the lateral quadrants, and the ventral ganglion of those cell bodies located in the ventral quadrant and clustered about the ventral posterior extension of the nerve ring neuropil.

The mouth is having three distinct lips. The position of angle of mouth in Ascaris is one ventral and two dorso lateral.

It's a fact. That is why many people there suffer from Ascariasis or Filariasis. Thus most commonly found in Philippines.

Hemoglobin or haemoglobin, abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein in the red blood cells of almost all vertebrates as well as the tissues of some invertebrates. The eggs can then mature into a form of the parasite that is infective. Ascariasis is caused by ingesting eggs. Heavy infections can cause intestinal blockage and impair growth in children. Other symptoms such as cough are due to migration of the worms through the body.

Circular muscles are absent in the round worms. The longitudinal muscles form single layer of spindle-shaped cells below the epidermis. The longitudinal muscles are interrupted at four places by longitudinal epidermal chord. The muscle layer is divided into four longitudinal columns and two ventro-lateral columns.
Each muscle cell has a fibrillar, contractile muscular portion and a granular non-contractile protoplasmic portion projecting into body cavity. The contractile muscular portion contains longitudinal contractile fibres arranged at intervals.

Metamerism: In some animals, the body is externally and internally divided into segments with a serial repetition of at least some organs. For example, in earthworm, the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism or true segmentation. Metamerism is found in 3 animal phylums - Annelida, Arthropoda and Chordata.

Microvilli are most often found in the small intestine, on the surface of egg cells, as well as on white blood cells. In the intestine, they work in conjunction with villi to absorb more nutrients and more material because they expand the surface area of the intestine.
A brush border is the microvilli-covered surface of simple cuboidal epithelium and simple columnar epithelium cells found in certain locations of the body. The brush borders of the small intestinal lining are the site of absorption.

Dorsal, ventral and lateral longitudinal nerves arise from the brain and extend posteriorly in the epidermal cords. Of these the ventral nerve cord is most important and is a double ganglionated cord.

Ascaris is an intestinal parasite of humans. It is the most common human worm infection. The larvae and adult worms live in the small intestine and can cause intestinal disease.
The pseudocoelom is a fluid-filled body cavity lying inside the external body wall of the nematode (Ascaris) that bathes the internal organs, including the alimentary system and the reproductive system. The coelozoic parasite lives within the cavities of the host's body.

It is parasite which lives in intestine and you must know that the pH of intestine is harsh. So, for the survival of ascaris, they possess thick cuticle as an essential for self-defense to prevent the medium from digesting ascaris as well.

The excretory system consists of one or two large renette gland cells lying ventrally in the pseudocoel near the junction of the pharynx and intestine, a dust arises from each renette cell, these ducts join and open by an excretory pore mid- ventrally.

The pharynx of the nematode Ascaris suum: structure and function. The pharyngeal muscle of nematodes consists of a syncytium of radial muscle whereby feeding occurs by the process of pharyngeal pumping.

 The cuticle is separated from the epidermis by a basement membrane. This is a thin, syncytial, ectoderm layer.

Nematodes move by contraction of the longitudinal muscles. Because their internal pressure is high, this causes the body to flex rather than flatten, and the animal moves by thrashing back and forth. No cilia or flagellae are present.
The nematode cuticle is an extremely flexible and resilient exoskeleton that permits locomotion via attachment to muscle, confers environmental protection and allows growth by molting.

Syncytia : An epithelium or tissue characterized by cytoplasmic continuity, or a large mass of cytoplasm not separated into individual cells and containing many nuclei. Supplement. Syncytium may be formed by the fusion of two or more cells, forming a giant cell.
Somatic muscle cells of Ascaris lumbricoides consist of three differently specialized components referred to as the fiber, which contains the contractile apparatus (described previously), the belly, and the arm. The belly is shown to be a sac of glycogen, which is depleted during starvation of the animal.

A cuticle, or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homologous, differing in their origin, structure, function, and chemical composition.

The mouth of the ascaris has three lips with small teeth which are called denticulate. On the inner surface, they are dented. So, the correct answer is Option B.

In Ascaris muscle mitochondria the major respiratory chain- linked phosphorylation activity is accomplished by a NADH- linked reduction of fumarate to succinate. The end products are butyric acid, valerianic acid and caproic acid.

Parasitic animals show a number of parasitic adaptations. The presence of though, thick and resistant cuticle. This cuticle covers entire body and gibes protection against the action of the digestive enzymes and antitoxins of the host. On the other hand Ascaris itself also secreted several anti-enzymes to protect itself from digestive enzymes of host.
Anaerobic mode of respiration and extremely low metabolic rate helps the worms live inside the intestine of the host where there is no availability of free oxygen.
Muscle cells of its body wall contract against the pressure of pseudocoelomic fluid to bring about undulations of the body that counteract the force of peristalsis of host intestine . Thus pseudocoelomic fluid is well adapted for hydrostatic skeleton.
Since, pseudo segmentation has no role in parasitic adaptation of ascaris.

Nematodes thrive in a plethora of environments, although many are parasitic. The muscular system of nematodes is very simple. Long muscles stretch the entire length of the body and are found underneath the epidermis, and the muscles are controlled by the ventral and dorsal nerves that run the entire length of the roundworm.

Cytochromes are the part of haemoprotein,which help out in cellular respiration and hemoglobin are very bonded to oxygen . that's why they both carry out the aerobic respiration.

The nervous system of the nematode worm Ascaris contains about 250 nerve cells; of these, the motoneurons consist of five segmental sets, each containing 11 cells.