Biology: Platyhelminthes Overview
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Questions and Answers

Which characteristic is NOT true for the phylum Platyhelminthes?

  • They have a complex respiratory system (correct)
  • They have flame cells in their excretory system
  • They can be free living or parasitic
  • All members are hermaphrodites

    • All organisms in the phylum Platyhelminthes have a respiratory system.

    False

    What is the main function of flame cells in the excretory system of Platyhelminthes?

    To collect excess water and excretory wastes

    Platyhelminthes are _____ symmetrical organisms.

    <p>bilaterally</p> Signup and view all the answers

    Match the following characteristics with the correct description:

    <p>Hermaphrodites = Organisms with both male and female reproductive organs Free living = Not dependent on a host for survival Flame cells = Cell structures involved in osmoregulation Parasitic = Dependent on a host for survival</p> Signup and view all the answers

    What is one of the characteristics of the phylum Platyhelminthes?

    <p>Acoelomate with organs</p> Signup and view all the answers

    All organisms within the phylum Platyhelminthes have a flattened body structure.

    <p>True</p> Signup and view all the answers

    What type of body structure do Platyhelminthes have?

    <p>Acoelomate</p> Signup and view all the answers

    The body wall of organisms in the phylum Platyhelminthes consists of three ______.

    <p>layers</p> Signup and view all the answers

    Match the following characteristics to their descriptions related to Platyhelminthes:

    <p>Acoelomate = Lacking a body cavity Flattened body = Distinctive shape of the organisms in this phylum Three tissue layers = Body wall composition Organs present = Organ systems developed within the body</p> Signup and view all the answers

    What structure in the excretory system is responsible for collecting excess water and waste?

    <p>Flame cells</p> Signup and view all the answers

    The nervous system has a ladder-like arrangement with longitudinal nerves connected transversely.

    <p>True</p> Signup and view all the answers

    What term describes organisms that have both male and female reproductive organs?

    <p>Hermaphrodites</p> Signup and view all the answers

    The eyespots are located near the ________ ganglia.

    <p>cerebral</p> Signup and view all the answers

    Match the following systems or structures with their descriptions:

    <p>Excretory tubules = Open to outside through excretory pores Cerebral ganglia = Located at the anterior end Flame cells = Collects excess water and wastes Eyespots = Detects light</p> Signup and view all the answers

    What is the initial host that Miracidium invades?

    <p>Lymnaea</p> Signup and view all the answers

    Cercaria is a larva that is capable of swimming.

    <p>True</p> Signup and view all the answers

    What larval stage develops from Miracidium within the snail?

    <p>cercaria</p> Signup and view all the answers

    The larva that develops from Miracidium is called _____ and is capable of swimming.

    <p>cercaria</p> Signup and view all the answers

    Match the following stages of development with their characteristics:

    <p>Miracidium = Invades aquatic snail Cercaria = Swimming larva with large tail</p> Signup and view all the answers

    What does the larva primarily do after contacting the parasite?

    <p>Starts eating liver cells</p> Signup and view all the answers

    The larva of the parasite spends several months eating the liver.

    <p>False</p> Signup and view all the answers

    How long does the larva usually browse and eat the liver?

    <p>A few weeks</p> Signup and view all the answers

    Which class includes free-living worms found in salt water or fresh water?

    <p>Class Turbellaria</p> Signup and view all the answers

    The larva finds the liver and starts eating _____ cells.

    <p>liver</p> Signup and view all the answers

    Match the following stages of the larva's behavior with their descriptions:

    <p>Initial contact = Larva starts eating liver cells A few days later = Larva continues to browse After weeks = Larva consumes liver cells</p> Signup and view all the answers

    All members of the Platyhelminthes phylum are parasitic.

    <p>False</p> Signup and view all the answers

    What are the two environments where turbelleria class worms can be found?

    <p>salt water or fresh water</p> Signup and view all the answers

    The subkingdom of Platyhelminthes belongs to the larger classification system called __________.

    <p>Metazoa</p> Signup and view all the answers

    Match the following classes with their characteristics:

    <p>Turbellaria = Free-living in aquatic environments Trematoda = Parasitic flatworms Cestoda = Tapeworms typically found in the intestines of hosts Platyhelminthes = Phylum of flatworms</p> Signup and view all the answers

    Study Notes

    Platyhelminthes

    • Phylum of acoelomate animals
    • Body wall has three layers
    • Flattened and bilaterally symmetrical
    • Hermaphrodites (except Shistosoma)
    • Free-living or parasitic
    • Respiration by simple diffusion
    • Lacking a respiratory system

    Excretory System

    • Flame cells (protonephridia)
    • Collect excess water and wastes
    • Connected to excretory tubules that exit to the outside

    Nervous System

    • Cephalized with a pair of cerebral ganglia at the anterior end
    • Two longitudinal nerve cords connected transversely
    • Ladder-like arrangement

    Sense Organs

    • Two cup-shaped eyespots near the cerebral ganglia

    Sexual Reproduction

    • Hermaphroditic (possess both male and female reproductive organs)
    • Fertilization occurs simultaneously when two worms mate
    • Eggs are laid in protective capsules

    Asexual Reproduction (Regeneration)

    • Fission occurs in some species, specifically Planaria
    • Posterior part of the worm attaches to a surface
    • Body constricts behind the pharynx
    • Anterior part moves forward, splitting the worm into two
    • Each half regenerates to become a complete Planaria

    Class Turbellaria

    • Free-living in fresh or saltwater
    • Resemble a plant leaf, covered by cilia
    • Possess suckers
    • Planaria species live in fresh water, hiding beneath rocks and water plants
    • Planaria possesses a dorsal surface that points upwards and a ventral surface directed downwards

    Class Trematoda (Flukes)

    • Leaf-like, unsegmented bodies
    • Typically have two suckers (oral and ventral)
    • Gastrovascular cavity bifurcates into two intestinal caecae
    • All are parasitic, except for Shistosoma
    • Hermaphrodites

    Fasciola gigantica Life Cycle

    • Female lays eggs in the liver of an infected human
    • Immature eggs are discharged into biliary ducts and feces
    • If eggs land in water, they develop into miracidia
    • Miracidia infect a snail (e.g., Lymnaea)
    • Develop into cercariae, which encyst on aquatic plants
    • Humans or other animals ingest the encysted metacercariae
    • Metacercariae develop into adults in the liver's bile ducts

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    Platyhelminthes PDF

    Description

    Explore the fascinating phylum Platyhelminthes, which includes acoelomate animals like flatworms. This quiz covers their unique body structure, nervous and excretory systems, as well as their methods of reproduction. Test your knowledge on these intriguing organisms and their characteristics!

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