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Questions and Answers
Which of the following ecological roles is associated with nematodes?
Which of the following ecological roles is associated with nematodes?
- Primary producers in aquatic ecosystems
- Parasitic agents in animal hosts
- Both B and C (correct)
- Decomposers of organic matter in soil
Nematodes possess a body cavity known as a coelom, which is fully lined with mesodermal tissue.
Nematodes possess a body cavity known as a coelom, which is fully lined with mesodermal tissue.
False (B)
What is the primary mechanism for circulation in nematodes?
What is the primary mechanism for circulation in nematodes?
- Diffusion through the body tissues (correct)
- An open circulatory system with hemolymph
- Specialized respiratory pigments
- A closed circulatory system with vessels and a heart
In Ascaris lumbricoides, the infective stage occurs when fertilized eggs develop into _______.
In Ascaris lumbricoides, the infective stage occurs when fertilized eggs develop into _______.
Match the following components of the Ascaris digestive system with their functions:
Match the following components of the Ascaris digestive system with their functions:
What is the significance of Ascaris larvae migrating to the lungs in a host?
What is the significance of Ascaris larvae migrating to the lungs in a host?
All species of nematodes are parasitic, relying on a host organism for survival and reproduction.
All species of nematodes are parasitic, relying on a host organism for survival and reproduction.
Explain how the lack of a specialized respiratory system in nematodes is compensated for by their body structure and lifestyle.
Explain how the lack of a specialized respiratory system in nematodes is compensated for by their body structure and lifestyle.
What is the main route of transmission for Trichinella to humans?
What is the main route of transmission for Trichinella to humans?
What primary adaptation allowed parasitic worms to thrive in environments with less competition?
What primary adaptation allowed parasitic worms to thrive in environments with less competition?
Flashcards
Phylum Nematoda
Phylum Nematoda
Roundworms belong to this phylum.
Bilateral Symmetry
Bilateral Symmetry
Having a body plan in which the left and right sides are mirror images.
Nematode Ecological Roles
Nematode Ecological Roles
The ecological role of Nematodes can be...
Body organization
Body organization
The mesoderm, ectoderm, and endoderm.
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Pseudocoelom
Pseudocoelom
A body cavity that is not completely lined by mesoderm.
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Nematode Digestion
Nematode Digestion
A complete digestive system consisting of a mouth and an anus.
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Dioecious
Dioecious
Having separate sexes; male and female individuals exist.
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Nematode Circulation
Nematode Circulation
The diffusion of oxygen into cells for respiration.
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Nematode Habitat
Nematode Habitat
Nematoda's habitat is...
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Trichinella
Trichinella
From undercooked pork which causes the disease Trichinosis.
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- Roundworms belong to the Phylum Nematoda.
- Examples of roundworms include Trichinella, hookworms, and nematodes.
Characteristics of Phylum Nematoda
- Roundworms exhibit bilateral body symmetry.
- They can be parasitic, serve as a food source, aerate soil, and break down material.
- Roundworms have a 3-layered body organization consisting of endoderm, mesoderm, and ectoderm.
- Their body cavity is a pseudocoelom.
- Roundworms have a complete digestive system featuring both a mouth and an anus, along with specialized organs.
- Roundworms reproduce sexually and are dioecious, meaning they have separate sexes; asexual reproduction is absent.
- Circulation occurs through diffusion.
- The nervous system is characterized by a brain, a ganglion, nerves and sensory organs.
- Respiration happens through diffusion via the skin.
- Excretion takes place through the anus and tubes.
- Habitats include both hosts (intestine or blood) and soil.
- Most roundworms are free-living and harmless; however, some are parasitic.
- Trichinella, acquired from undercooked pork, causes the disease trichinosis.
- Hookworms use hooks and sharp teeth to burrow into hosts.
- Parasitic worms evolved to occupy environments with less competition.
Ascaris lumbricoides Life Cycle
- Ascaris lumbricoides is a parasitic nematode and a small intestinal roundworm.
- Ascaris worms are long, slender, and giant, with males being shorter than females.
- Their body is smooth and unsegmented.
- Infections begin in the small intestine of humans, where adult Ascaris worms release fertilized eggs.
- Fertilized eggs mix with feces and are released into the environment.
- Fertilized eggs develop further, becoming infective and transforming into larvae.
- Embryonated eggs are expelled from the host through feces into the external environment.
- They live freely in soil or water.
- Hosts become infected by coming into contact with soil and water containing eggs or larvae, which then enter their stomach.
- Eggs hatch within the host, and larvae invade the intestinal mucosa before circulating and migrating to the lungs.
- In the lungs, larvae mature further over 10–14 days to penetrate the alveolar wall.
- The matured larva then moves up the bronchial tree into the throat, is swallowed, and enters the stomach.
- Returning to the small intestine, they complete their development into adult worms, which takes approximately 2–3 months.
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