BIO 240 Notes Week 7
BIO 240 Notes Week 7 BIO 240
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This 4 page Class Notes was uploaded by Miriam Valenzuela on Thursday March 12, 2015. The Class Notes belongs to BIO 240 at San Francisco State University taught by Dr. Andrew Swei and Dr. Dennis Desjardin in Spring2015. Since its upload, it has received 69 views. For similar materials see Second Semester Biology in Biology at San Francisco State University.
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Date Created: 03/12/15
Biology 240 Notes for Week 7 Origin of the Seed Carboniferous period warm and wet climate dominated by seedless plants seeds developed in dry habitats Progymnosperms ancestors of seeds Permian Period habitat became dry radiation of seed plants favored plants due to dry conditions Mesozoic Era forests dominated by conifers and cycads Diversification of Plants Heterosporous female sporangium and male sporangium increased genetic variability Gametophytes develop on sporophyte gametophytes develop on parent sporophyte where for protection and food Nonmotile sperm development of pollen grain vascular tissue gives way to the development of wood through the production of the cambium layer Evolutionary Advantage of Seeds Seeds are multicellular seeds contain baby plant seeds contain nutrients Gymnosperms Naked seed plant exposed seed on surface oldest fossils Phylum Ginkgophyta Gingko Ginkgo Biloba one species exists today deciduous and dioecious deciduous sheds leaves once a year dioecious male plants and female plants unisex in different individuals Phylum Cycadophyta Cycads 185 Species in 11 genera circinate vernation arrangement of leaves around a bud in a fern like structure male and female cones evergreen and dioecious evergreen never sheds their leaves dioecious male and female parts in d Phylum Gnetophyta Gnetophytes 3 genera Gnetum 35 species monoecious and dioecious Monoecious having both male and female structures in different structures Dioecious male and female parts in different individuals Ephedra branches and scale like leaves dry areas prefered dioecious male and female parts in different individuals Welwitschia one species roots below ground dioecious male and female parts in different individuals Phylum Coniferophyta Conifers woody stems trees and shrubs male cones and female cones needleshaped leaves mostly monoecious few dioecious mostly evergreens few deciduous dominate forests sunken stomata closed cones thick bark Seed and Ovule megagametophyte is a source of nutrition for embryo seed coat derived from integument Angiosperms Enclosed Seed Plants Phylum Anthophyta Flowering Plants Evolved from Gnetophytes Cretaceous Era 130 mya continents beginning to form cooling period extinction event Evolution of Enclosed Seed carpel enclosement tissue of the seed in Angiosperms rapid speciation seed dispersal fruit geographically isolated populations stigma development Flowers Pollination movement of pollen from stamen to stigma nonselective random large population needed not ensured pollination metabolically expensive to produce pollen Animal Pollinated beetle pollinated first animals visited for food development of fruit as food resources Flower Morphology sepals form the calyx which provides protection to the flower petals form the corolla which attracts pollinators stamen are the male reproductive organs anthers are the microsporangia filaments elevate anthers for dispersal of the pollen grains carpels are the female organs used for the production of seeds ovary contains ovules which are megasporangia style rises the stigma for successful collection of pollen stigma collects pollen Double Fertilization sperm nuclei migrate down the pollen tube towards the ovule The are two sperm present Double Fertilization Two sperm one of them fuses with egg nucleus development of the embryo through the zygote second one fuses with the central nuclei to produce the endosperm nucleus Distinct Features of Angiosperms ovules enclosed in ovary reduction of gametophytes unique double fertilization seed develops and matures in months animal pollination vessels in xylem
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