Ch. 30_Plant Diversity II_The Evolution of Seed Plants.docx...

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Ch. 30: Plant Diversity II: The Evolution of Seed PlantsAdaptations of Seed PlantsReduced GametophytesoGametophytes develop within the walls of spores that are retained within tissues of theparent sporophyte.oThe majority of the plant you see is the sporophyte.oIt is beneficial for the gametophyte to be in a controlled environment.HeterosporyoSeed plant ancestors were likely homosporous, while seed plants areheterosporous.oMegasporangiaproduce megaspores that give rise to female gametophytes.oMircosporangiaproduce microspores that give rise to male gametophyes.Ovules and the Production of EggsoAn ovule consists of a megasporangium, megaspore and one or more protectiveinteguments.oA female gametophyte develops from the megaspore and produces 1 or more eggs.Pollen and Production of SpermoInside microsporangium, microspores develop into pollen grains that contain the malegametophytes (which produce sperm).oPollen are covered in a tough coat and can be dispersed great distances by air oranimals.Advantages of SeedsoSpores were the way that plants spread over the earth for the first 100 million years oflife.

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Term
Spring
Professor
dr.wolin

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