BIOL 152 1st Edition Lecture 11 Outline of Last Lecture I The green algae are the closest relatives of the land plants a Green algae and land plants share many features b Green algae are NOT monophyletic c The Caryophyceans are sister to the land plants II The colonization of Earth presents many challenges a Consider the habitat s of the ancestors of land plants b Review the major challenges III A series of key innovations permit colonizing Earth a Reflect upon the synapomorphies of land plants b Leaf morphology illustrates some of the solutions to desiccation c Stoma or stomates regulate water loss in many plants IV One clade of land plants evolved complex vascular tissues a Xylem is a complex tissue that functions to transport water b Energy is not required to move water c Phloem is a complex tissue that functions to transport the product of photosynthesis d Energy IS required for phloem to move sugars via bulk flow Outline of Current Lecture I Summary of plant transport systems a Water nutrients b Bulk flow II The move to land a Preventing desiccation b Confronting gravity c Exploring complex habitats III Alteration of generations a Generic b Humans IV Diploid haploid organisms V Plant life cycle summary a Examples VI Gymnosperms a Homospory b Heterospory These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Current Lecture Summary of plant transport systems Water and nutrients pulled up by xylem o Driven by transpiration Bulk flow of photosynthesis from sucrose to sink through phloem o Driven by hydrostatic pressure The move to land Preventing desiccation o Sporopollenin o Cuticle Confronting gravity o Lignin stiff cell walls xylem Exploring complex habitats o Alteration of generations o Multicellular haploid diploid phases Alteration of generations 2n diploid Meiosis reduction division n haploid Fertilization fusion sperm egg Humans Ovary testes Meiosis gametes are unicellular sperm egg Fertilization Mitosis fetus 2n mitosis Diploid haploid organisms Meiosis changes a diploid to a haploid Fertilization changes a haploid to a diploid Human diploid complex and multicellular Human haploid unicellular not really a generation In plants both diploid and haploid generations are MULTICELLULAR Diploid sporophyte sporangia by mitosis meiosis spore Multicellular haploid mitosis sperm egg FERTILIZATION zygote mitosis Plant Life Cycle Summary Diploid generation sporophyte Haploid generation gametophyte o Sporophyte mitosis sporangia o Sporangia mitosis spores o Spores mitosis gametophytes o Gametophytes mitosis gametes o Gametes fertilization egg sperm zygote Ex Moss Sporophyte multicellular Sexual reproduction o Gametophytes maturation gametongial shoots o Sperm swims in film of water to egg o Zygote 2n mitosis sporophyte shoot Ex Ferns Diploid haploid generations that become independent plants Diploid 2n meiosis spores dispersal of spores by wind germination fertilization sperm swims to egg water required gametophyte mature sporophyte Gymnosperms Gametophyte is now dependent on sporophyte Homospory vs heterospory Homosporous plants are ferns and moss o Sporophyte one sized spores by meiosis bisexual gametophyte by mitosis egg or sperm Heterosporous plants are seed plants o Sporophyte megaspores or microspores by meiosis female gametophyte or male gametophyte by mitosis egg or sperm Female cone vs Male cone Female cone megaspore ovule Male cone microspore pollen o Pollen is dispersed by wind pollination does not require water
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