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Questions and Answers
What is the shape of the Amylum stars formed in vegetative reproduction?
What is the function of the pedicel in sexual reproduction?
What is the type of reproduction in which Oogamy occurs?
What is the number of sterile cells surrounding the ovum in the Oogonium?
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What is the shape of the aggregation of cells formed on the rhizoids in vegetative reproduction?
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What is the function of the shield cells in the Antheridium?
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What is the number of primary capitulum cells that bear antheridial filaments?
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What is the result of the fusion of an antherozoid with the ovum?
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What is the characteristic of the main axis of Chara?
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What is the function of rhizoids in Chara?
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What is the characteristic of the internode in Chara?
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What is the type of growth observed in the branchlets of Chara?
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What is the characteristic of the chloroplasts in Chara?
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What is the stage that develops from a germinated zoospore in Chara?
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What is the characteristic of the node in Chara?
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What is true about the life cycle of Chara?
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What is the composition of the cell wall in Cladophora?
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How do the zoospores of Cladophora emerge from the parent cell?
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What is the type of conjugation that occurs between gametes produced in two adjacent cells of the same filament?
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What is the characteristic of the filaments in Cladophora?
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How do the diploid and haploid filaments of Cladophora differ?
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What is the characteristic of the storage food material in Charophytes?
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What is the type of reproduction that occurs when a filament of Cladophora fragments into two or more pieces?
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What is the characteristic of the zoospores formed in Cladophora?
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What is the type of alternation of generations exhibited by Cladophora?
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Where does the scalariform conjugation occur in Cladophora?
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Study Notes
Reproduction in Charophyta
- Reproduces vegetatively and sexually
Vegetative Reproduction
- Involves formation of aggregates of cells: Amylum stars, bulbils, and tubers
- Each of these structures can withstand adverse environmental conditions and give rise to new plants during the growth season (August to March)
Sexual Reproduction: Oogamy
- Plant is usually monoecious (Antheridia and Oogonia) on the same plant
- Organs are borne in proximity to each other on the same node of a lateral branch
- Antheridium is globose, surrounded by a wall with shield cells, and supported by a stalk (pedicel) with primary capitulum
- Each antheridial filament can produce a single spiral antherozoid (male gamete) with two sub-apical flagella
- Oogonium contains a single ovum (female gamete) surrounded by sterile cells (tube cells) that twist and form a crown-like structure (corona)
Features of Charophyta
- Thallus has an erect axis with whorled branches and rhizoids, with nodes and internodes, and apical and unlimited growth
- Zoospores germinate to form an intermediate stage (protonema) before growing into a new plant
- Sexual organs have complexity due to the presence of many sterile cells
Classification
- Division Charophyta includes a single class Charophyceae with one order Charales
- Order Charales includes few genera such as Chara, Nitella, Nitellopsis, and Tolypella
Chara
- Grows in fresh water, stagnant or slowly running, and is fixed to the muddy bottom or stones through rhizoids
- Thallus has an internode composed of one long multinucleate cell in the center, surrounded by corticating cells
- Node is composed of uninucleate cells with some cells behaving as apical cells, leading to the formation of branchlets in a whorled fashion
- Chloroplasts are present in cells as a large number of ellipsoidal chloroplasts streaming in the peripheral cytoplasm
- Rhizoids are filamentous, uniseriate, devoid of chloroplasts, and branched structures
Reproduction in Chara
- No asexual life cycle, reproduces by conjugation between two conjugating filaments
- Conjugation results in the formation of a zygote, which subsequently affords a dark thick wall and rests for a time before germinating
Cladophora
- Cells are multinucleate and placed end to end
- Widespread in fresh or marine water habitats
- Filaments are branched, and the branching is lateral near the upper end of the cell
- Cell wall is composed of three layers: chitin, pectin, and cellulose
Reproduction in Cladophora
- Vegetative (by fragmentation), asexual (by zoospores), and sexual
- Asexual reproduction involves the release of quadriflagellate zoospores from pores in the cell walls
- Sexual reproduction involves the fusion of biflagellate isogametes from (+) and (-) haploid strains
Alternation of Generations in Cladophora
- The life cycle reveals isomorphic alternation of generations
- Two distinct individuals alternate with each other: the diploid filament (asexual plant) and the haploid individual (sexual plant)
- The diploid plant reproduces asexually by zoospores, while the haploid plant reproduces sexually by gametes
- The two plants resemble each other but differ in cytological details and function, with the diploid plant having 2N chromosomes and the haploid plant having 1N chromosomes
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Description
This quiz covers the vegetative reproduction process in plants, including the formation of amyllum stars, bulbils, and tubers. Understand the characteristics and functions of these structures.
