Algae Order II: Chlorococcales
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Questions and Answers

How many families are represented in the Order II: Chlorococcales?

  • Four
  • Five
  • Two
  • Three (correct)

    • Which of the following is a characteristic of Pediastrum?

  • Colonial forms
  • Unicellular and uninucleate
  • Multinucleate
  • Peripheral cells with protrusions (correct)

    • What is the method of asexual reproduction in Pediastrum?

  • Formation of autocoenobia (correct)
  • Spore formation
  • Budding
  • Binary fission

    • What happens to the autocoenobia in Pediastrum after they are released from the mother cell wall?

    <p>They grow into new coenobia</p> Signup and view all the answers

    What type of reproduction is seen in Pediastrum?

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

    What is the meaning of the name Hydrodictyon?

    <p>Water net</p> Signup and view all the answers

    What is the shape of the chloroplast in Ulothrix?

    <p>Ring- or girdle-shaped</p> Signup and view all the answers

    How does Ulothrix grow?

    <p>Attached to solid objects</p> Signup and view all the answers

    What is the method of asexual reproduction in Ulothrix?

    <p>Through fragmentation and zoospores</p> Signup and view all the answers

    What is the shape of the cells in Ulothrix?

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

    How do members of the family Ulothricaceae reproduce sexually?

    <p>Through isogametes</p> Signup and view all the answers

    What is the shape of the filament in Ulothrix?

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

    What is the characteristic of an oogonium?

    <p>It is spherical and bright orange</p> Signup and view all the answers

    What is the term for species that produce small, flattened antheridia?

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

    What is the function of the distal end of the filament?

    <p>It functions as the antheridium</p> Signup and view all the answers

    What is the term for the small filamentous structure?

    <p>Dwarf male plant</p> Signup and view all the answers

    What happens to the androspores after they swim towards the oogonium?

    <p>They become attached to the oogonial wall</p> Signup and view all the answers

    What is the outcome of the germination of the zygote?

    <p>Production of zoospores</p> Signup and view all the answers

    What happens to hypnospores when they are exposed to unfavorable environmental conditions?

    <p>They acquire thick walls and dark pigments</p> Signup and view all the answers

    What is the characteristic of the gametes in isogamous reproduction?

    <p>They are biflagellate</p> Signup and view all the answers

    What is the fate of the zygote in the life cycle of Ulothrix?

    <p>It produces 4 or more quadriflagellate zoospores</p> Signup and view all the answers

    What is the characteristic of the chloroplasts in Oedogonium?

    <p>They have many pyrenoids</p> Signup and view all the answers

    What is the location of the nucleus in Oedogonium cells?

    <p>At the periphery of the cell</p> Signup and view all the answers

    What is the purpose of the holdfast in Oedogonium?

    <p>To attach to a substratum</p> Signup and view all the answers

    What is the characteristic of the scars on the Oedogonium filament?

    <p>They are of a certain shape known as caps</p> Signup and view all the answers

    What is the type of sexual reproduction in Oedogonium?

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

    Study Notes

    Order II: Chlorococcales

    • Families: Chlorococcaceae, Protosiphonaceae, and Hydrodictyaceae
    • Hydrodictyaceae:
      • Examples: Pediastrum and Hydrodictyon
      • Pediastrum:
        • Unicellular, planktonic, and flat colony
        • Peripheral cells have one or two protrusions
        • Asexual reproduction: formation of autocoenobia
        • Autocoenobia can grow into new coenobia if released from the enclosing mother cell wall
      • Hydrodictyon:
        • Name means "water net"
        • Nets are cylindrical with closed ends
        • Cells are cylindrical with many nuclei in the peripheral cytoplasm
        • Chloroplast is reticulate with pyrenoids
        • Asexual reproduction: mainly through autocoenobia formation
        • Sexual reproduction: isogamous

    Order III: Ulothricales

    • Family: Ulothricaceae
    • Members: found in various habitats, including freshwater, marine, and soil
    • Ulothrix:
      • Unbranched, uniseriate, cylindrical filament
      • Mostly grows attached to solid objects
      • Cells have single chloroplast, ring- or girdle-shaped, with one or many pyrenoids
      • Nucleus is enclosed in the chloroplast
      • Reproduction:
        • Vegetative: through fragmentation
        • Asexual: by zoospores, aplanospores, and hypnospores
        • Sexual: isogamous
      • Zoospores:
        • Either biflagellate or quadriflagellate
        • When at rest, they attach themselves to solid objects by flagella and grow into new filaments
      • Hypnospores:
        • Aplanospores that acquire thick walls and dark pigments in unfavorable environmental conditions
      • Isogametes:
        • Biflagellate
        • Facultative gametes that can behave as zoospores if they fail to fuse
      • Life cycle: haplontic (zygote is the only diploid phase)

    Order IV: Oedogoniales

    • Family: Oedogoniaceae
    • Only family in this order
    • Comprises only three genera: Oedogonium, Bulbochaete, and Oedocladium
    • Oedogonium:
      • Unbranched, uniseriate filament
      • Cells are uninucleate
      • Occurs in freshwater, attached by means of a basal holdfast as an epilithic or epiphytic alga
      • Chloroplasts possess many pyrenoids
      • Nucleus lies in the periphery of the cell
      • Filaments are polar due to the presence of the holdfast
      • Caps are residual portions of cells that divide to bring about intercalary growth
      • Reproduction:
        • Vegetative: through fragmentation
        • Asexual: by zoospores, akinetes, or aplanospores
        • Sexual: by oogamy
      • Zoospores:
        • Flagella are numerous and crown-like (up to 120)
        • After a period of motility, they attach themselves to a substratum and give new filaments
      • Sexual reproduction:
        • Oedogonium may be heterothallic or homothallic
        • Oogonium is formed by enlargement of a cap cell, which becomes spherical and bright orange
        • Antheridium can occur in one of two ways:
          • Macrandrous: small flattened antheridia are formed by successive rapid divisions of cap cells
          • Nannandrous: swarmer released from an antheridial-like cell, which does not work as an antherizoid, termed an androspore
      • Androspores:
        • Swim towards the oogonium, but do not fuse with it
        • Instead, they become attached to the oogonial wall or a cell nearby and germinate into small two- or three-celled filaments
      • The distal end of the filament functions as the antheridium
      • Zygote develops a two- or three-layered wall and undergoes a resting period before germinating by the production of zoospores

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    Description

    This quiz covers families and characteristics of Chlorococcales order, including Chlorococcaceae, Protosiphonaceae, and Hydrodictyaceae. Focuses on Pediastrum and Hydrodictyon examples.

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