Biology: Hornworts and Liverworts
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Questions and Answers

What is the characteristic of the spores in hornworts?

  • They have pseudo-elaters that twist and uncoil in response to changes in humidity.
  • They have a multicellular outer layer.
  • They produce cyanobacteria.
  • They have helical thickenings that change shape in response to changes in humidity. (correct)

    • What is the name of the cyanobacteria that invade the mucilage-filled cavities of hornworts?

  • Nostoc (correct)
  • Archegonium
  • Anthoceros
  • Columella

    • What is the origin of the name 'liverworts'?

  • The plant is used to treat liver diseases.
  • The plant has a liver-like function.
  • The thallus is divided into liver-shaped zones.
  • The shape of the thallus resembles a liver. (correct)

    • What is the function of the elaters in liverworts?

    <p>They help in dispersing plant spores.</p> Signup and view all the answers

    What is the shape of the sporophyte in hornworts?

    <p>Horn-like</p> Signup and view all the answers

    What is the structure from which the sporophyte grows in hornworts?

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

    What is the characteristic feature of the class Bryopsida?

    <p>Arthrodontous peristome</p> Signup and view all the answers

    Which class of bryophytes has the maximum number of genera?

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

    What is the name of the plant in which peristome teeth are present?

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

    What is the function of rhizoids in Bryopsida?

    <p>To anchor the plant to the soil</p> Signup and view all the answers

    Which class of bryophytes is characterized by the presence of pseudo-elaters?

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

    What is the term for the arrangement of leaves on the stem in Bryopsida?

    <p>Spirally arranged</p> Signup and view all the answers

    What is the function of elaters in bryophytes?

    <p>To help in the release of spores from the capsule</p> Signup and view all the answers

    Which of the following structures is considered the ancestor of vascular bundles in angiospermic plants?

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

    What is the type of sexual reproduction in the given life cycle?

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

    What is the role of the sporophyte in the life cycle?

    <p>It is totally dependent on gametophyte</p> Signup and view all the answers

    What is the mode of reproduction in which thallus breaks into pieces and each piece develops into a new thallus?

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

    What is the function of the archegonium in the life cycle?

    <p>It produces egg</p> Signup and view all the answers

    What is the name of the structure in which gemmae are produced in liverworts?

    <p>Gemma cups</p> Signup and view all the answers

    Which of the following is NOT a method of vegetative reproduction in bryophytes?

    <p>Asexual reproduction</p> Signup and view all the answers

    What is the result of the fusion of egg and antherozoid?

    <p>Formation of zygote</p> Signup and view all the answers

    What is the name of the structure that develops into a new individual in Funaria?

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

    What is the role of the protonema in the life cycle?

    <p>It breaks into small pieces to grow into new protonema</p> Signup and view all the answers

    What is the ploidy of the sporophyte in the life cycle?

    <p>Diploid (2n)</p> Signup and view all the answers

    What is the main reason for the slow decay of dead vegetative matter in bogs?

    <p>Absence of oxygen and decomposing microorganisms</p> Signup and view all the answers

    What is the primary use of peat in Ireland, Scotland, and Northern Europe?

    <p>Used as fuel</p> Signup and view all the answers

    What is the role of Sphagnum in the formation of peat?

    <p>It secretes acids that inhibit the growth of decomposing organisms</p> Signup and view all the answers

    Why are Bryophytes used as packing material for shipment of perishable fruits?

    <p>Due to their ability to hold water</p> Signup and view all the answers

    What is the benefit of using Bryophytes in nurseries?

    <p>They hold and absorb water</p> Signup and view all the answers

    What is another name for Sphagnum?

    <p>Peat moss</p> Signup and view all the answers

    Study Notes

    Gametophyte and Sporophyte Structure

    • Gametophyte can be a rosette or ribbon-like thallus.
    • Hornworts develop internal cavities filled with mucilage and inhabited by photosynthetic cyanobacteria, mainly Nostoc, giving them a blue-green hue.
    • Horn-like sporophyte emerges from an archegonium located deep within the gametophyte.

    Liverworts

    • Liverworts derive their name from the similarity of their thallus to liver lobes; "wort" means "herb."
    • The thallus in liverworts comprises distinct zones: photosynthetic zone, air chamber, and storage zone.

    Sporophyte Structures

    • In Anthoceros, the horn-shaped structure is a sporophyte, not a gametophyte.
    • The mature sporophyte contains a multicellular capsule, a central columella, and a tissue layer that produces spores.
    • Spores possess pseudo-elaters, which are multicellular and function in spore dispersal through hydroscopic movements.

    Bryopsida (True Mosses)

    • Bryopsida is the largest class of mosses, encompassing 95% of all moss species.
    • Gametophyte features a protonema and erect leafy shoots, with persistent spirally arranged leaves and rhizoids.
    • Sporophytes consist of foot, seta, and capsule, with a unique peristome architecture that aids in spore release.

    Reproductive Structures and Processes

    • Elaters in bryophytes are formed alongside spores and assist in their release during dry conditions.
    • Asexual reproduction methods include fragmentation, gemmae formation, and tubers.
    • Sexual reproduction is oogamous, involving the production of antherozoids in antheridia and eggs in archegonia.

    Life Cycle and Alternation of Generations

    • The life cycle involves fertilization of eggs by antherozoids, forming a diploid zygote that grows into a sporophyte.
    • The sporophyte releases haploid spores which germinate into the gametophyte, continuing the cycle.

    Peat Formation and Uses

    • Peat forms via the compression and carbonization of partially decomposed vegetative matter in bogs, primarily involving Sphagnum moss.
    • Sphagnum secretes acids that inhibit decomposition, allowing for significant accumulation of dead plant material.
    • Peat is utilized as fuel, in the production of various chemicals, to enhance soil texture in horticulture, as surgical dressings, and as packing material.

    Summary of Bryophyte Classes

    • Classes of bryophytes include:
      • Liverworts (Hepaticopsida)
      • Hornworts (Anthocerotopsida)
      • True mosses (Bryopsida), which are unique for their peristome teeth.

    Key Terminology

    • Elater: Structures that aid in spore dispersal through humidity changes.
    • Protonema: Initial stages of moss growth post-spore germination, capable of forming new plants.
    • Capsule: Structure of the sporophyte that releases spores.

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    Description

    This quiz covers the characteristics and features of hornworts and liverworts, including their gametophyte and sporophyte structures, and internal cavities with cyanobacteria.

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