Chapter 26_ Plant Diversity II_ The Evolution of Seed Plants.docx

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Chapter 26: Plant Diversity II: The Evolution of Seed PlantsReproductive Adaptations of Seed PlantsReduced and Retained GametophytesSeed plants are heterosporous Megaspores (grow into female gametophytes)Microspores (grow into male gametophytes)Both gametophytes mature within sporangiaHighly reduced in sizeProtected from drying and UV● OvulesThe megasporangium with retained megaspore and surroundingsporophyte tissueMegaspore grows into female gametophyteEgg produced and fertilized within ovule● PollenMicrospores retained; mature into pollen grains while within microsporangiumPollen grains - matures male gametophytes with sporopollenin protective coatingPollen grains travel (in air or by animal) to reach ovule-bearing parts - pollinationNew step in sexPollen grain then grows a pollen tube toward egg within ovuleSperm released within pollen tubeNo flagella in conifers and angiospermsFertilization occurs within ovuleNote: no rain/dew needed● SeedDevelops from fertilized ovule

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Term
Spring
Professor
Vaughn
Tags
Biology, Plants, Evolution, Pollination, Flowering plant, Pollen

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