30-Plant Diversity II-The Evolution of Seed Plants.ppt -...

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Plant Diversity II: ThePlant Diversity II: TheEvolution of Seed PlantsEvolution of Seed PlantsChapter 30Chapter 30
Concept 30.1: Seeds and pollen grainsare key adaptations for life on landCharacteristics common to all seed plants1.Seeds- housing for the embryo2.Reduced gametophytes (size)- sporophyte is larger thangametophyte3.Heterospory- being able to produce both male and femalespores4.Ovules- eggs5.Pollen- vehicle for sperm
Gametophyte/sporophyte relationshipsGametophytes of seed plants develop within the walls of spores retainedwithin tissues of the parent sporophyteNo longer dependent on water for fertilizationFigure 30.2
Ovules and Production ofEggsAn ovule consists of a megasporangium (tissue that makes the megaspore),megaspore (eventually becomes the egg), and protective integuments (hair, nails,skin in humans; acts as a barrier)Figure 30.3a
Pollen and Production of SpermMicrospores (sperm) develop into pollen grainsContain ♂ gametophytePollen can be dispersed by water, air or animals, eliminates the need forwater in fertilization )means transporting egg from one plant to that ofanotherSperm is smaller than the egg
If a pollen grain germinates,It gives rise to a pollen tube that discharges sperm into the ♀ gametophyte within theovuleGermination- development into something more complexPollen tube releases sperm into female gametophyteFigure 30.3b
A SeedDevelops from the whole ovuleIncludes sporophyte embryo, food supply, protective coatEvery seed contains a plant embryoSporophyte is the dominant generationSome seeds are going to be harder than othersSeeds can survive even when eaten by animals and stays whole throughout the digestive system, come outthrough defecation and seed is now dispersedFigure 30.3cPine seed

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Term
Spring
Professor
GREGG
Tags
Biology, Plants, Evolution, Pollen, Pinophyta, pollen grains, Seed bearing plants

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