Chapter 28 Notes
Chapter 28 Notes Life103
Popular in Biology of Organisms-Animals and Plants
Popular in Entomology
This 6 page Class Notes was uploaded by Courtney Potter on Thursday October 29, 2015. The Class Notes belongs to Life103 at Colorado State University taught by Shane Kanatous; Graham Peers in Summer 2015. Since its upload, it has received 42 views. For similar materials see Biology of Organisms-Animals and Plants in Entomology at Colorado State University.
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Date Created: 10/29/15
Chapter 29 How Plants Colonized Land Land Plants Evolved From Green Algae 0 290000 plant species Are found in all environments Plants Are Complex 0 Physiologically and morphologically exible 0 Complex biochemistry 0 Complex ecology 0 History of Plant Evolution 0 Cyanobacteria a photosynthetic prokaryote creates atmospheric oxygen 0 Oldest known eukaryotic cells appear 0 Marine algae are abundant and plants begin to colonize land 0 Vascular plants form and rst seed plants appear Morphological and Molecular Evidence 0 Characteristics shared with algae eukaryotic multicellular photosynthetic autotrophs 0 Cell wall composed of cellulose dino agellates green algae and brown algae o Chloroplasts with chlorophylls green algae euglenids and dino agellates Charophytes group of green algae and Embryophytes plants share a common ancestor o Embryophytes evolved morphological features to adapt to land and became very diverse Multicellularity evolved independently many times in both green algae and plants Traits shared by Embryophytes and Charophytes 0 Rings of cellulose synthesizing proteins Protein rings that synthesize cellulose micro brils of the cell wall The protein rings stick together in groups of six called Rosette subunits 0 Completely Different Way of Cell Division Cleavage microtubules Phragmoplast and micro laments line perpendicularly and form the cell wall before they split 0 Structure of Flagellated Sperm Resembles Charophyte sperm Adaptations Enabling the Move to Land 0 Problems plants faced when moving to land 0 Dehydration avoided by forming a cuticle waxy layer around plant and sporopollenin also found in some Charophytes o Motile sperm physical support hydrostatic support getting nutrients temperature locomotion Five Derived Traits of Land Plants not found in Charophytes 1 Alteration of Generations o Gametophytemitosis of haploid gametes eggs and sperm fused forming diploid zygotes o Mitotic division of this zygote produces a multicellular diploid sporophyte o Sporophyte produces unicellular haploid spores 0 Spore products of meiosis in diploid sporophyte develop into new haploid organism without fusing with another cell 0 Spore undergoes mitosis forming a new multicellular haploid gametophytes 2 Multicellular Dependent Embryos 0 Why land plants are known as Embryophytes zygote retained within maternal tissue of female parent and given nutrients through placental transfer cells 3 Walled Spores Produced In Sporangia o Sporophyte contains multicellular organs called sporangia Within the sporangia there are diploid cells sporocytes that undergo meiosis to generate the spores 4 MulticellularGametangia o Multicellular organs within gametophytes that produce gametes o Archegonium produce and house the eggs 0 Antheridia produce the sperm 0 These structures have been lost in seed plants 5 Apical Meristems 0 Regions in the shoots and roots that are active sites of cell division 0 They help nd nutrients from the sun and carbon dioxide in the shoots and nutrients and water in the roots Stomata pores that allow oxygen out of the plant and let carbon dioxide in 0 Can close to minimize water loss 0 Plants without roots formed symbiotic relationships with mycorrhizal fungi that form laments in the soil extracting nutrients for the plant Origin and Diversi cation of Plants Spores found around 470 Mya with chemical composition of plants and structural composition of plants some date back to 450 Mya in plant cuticles Cooksonia found 425 Mya to resemble larger plant structures 0 Distinguishing Plants 0 Vascular plants have vascular tissue cells joined in tubes transporting water and nutrients to body Nonvascular plants or Bryophytes grade don t have this tissue liverworts mosses hornworts Vascular Plant Groups Lycophytesclub mosses and relatives clade Monilophytesferns and relatives clade Seedless Vascular plants grade Seed plants clade oz Gymnosperms seeds not enclosed in chambers oz Angiosperms seeds develop in chambers and are owering plants Grades are unlike clades since they do not have to share an ancestor they are grouped according to anatomical features Mosses and Other Nonvascular Plants Have Life Cycles Dominated by Gametophytes o Bryophytes nonvascular plants have three phyla o Phylum Hepatophyta Liverworts o Phylum Bryophyta Mosses o Phylum Anthocerophyta Hornworts Earliest lineages to emerge from common ancestor of land plants 0 Spores of liverworts mosses and hornworts appeared before the spores of vascular plants Bryophyte Cade Gametophytes Longer living and larger gametophytes than sporophytes life stages 0 Germinating moss spores produce thick green onecelled laments called protonema 0 Produce budlike growths in high nutrient areas with apical meristem generating a gametophore o Anchored by rhizoids long tubular cells not composed of tissue 0 Have archegonia and antheridia 0 Many found in moist habitats due to agellated sperm Bryophyte Cade Diversity o Phylum Hepatophyta Liverworts o Livershaped gametophytes 0 Can be described as thalloid because gametophytes are attened o Gametophytes hang from stalk surrounded in a capsule o Phylum Anthocerophyta Hornworts o Gametophytes cover the ground 0 Sporophytes contain sporangium and don t have a seta tall 0 Symbiotic relationship with cyanobacteria Phylum Bryophyta Mosses o Gametophytes no longer than 15cm blades one cell thick 0 Sporophytes have a capsule and seta and are around 20cm 0 Sphagnum or peat moss forms deposits of partially decayed organic material called peat Used as fuel Carbon reservoir for the globe overharvesting or loss of water could release carbon dioxide into the atmosphere Bryophyte Clade Sporophytes Sporophyte remains attached to gametophyte all its life relies on it for nutrients o The foot in Archegonium absorbs nutrients from gametophyte Setastalk leads materials to sporangium Capsule sporangium uses nutrients to create spores from meiosis o Peristome teeth looking structure on top of seta opens in dry weather Reproductive Cycle of Bryophyte Clade Spores are released into the air by the sporangiagt become multicellular haploid gametophytesgtform gametes in the Gametangia gtantheridia produces the spermgtarchegonia produces eggs 0 homosporous Carbon Dioxide Coming into Mosses o Gametophyte stagethe cuticle slowly diffuses carbon dioxide 0 Sporophytes have a stoma pore to let in carbon dioxide Mosses don t have roots they have rhizoids mosses and hornworts The Ecological and Economical Importance of Masses Inhabit extreme climates deserts mountaintops tundra Can lose most of body water and still survive Phenolic compounds can absorb suns damaging UV rays Sphagnum moss creates decayed organic matter deposits in wetland areas called peat 0 Used as fuel in some countries responsible for 30 of soils carbon Ferns and Other Seedless Vascular Plants Were the First Plants to Grow Origins and Traits of Vascular Plants 0 Lignin provides strength to the cell wall of plants and makes them inedible to many predators Branched sporophytes not dependent on gametophytes Competition for sunlight made vascular plants more diverse 0 Life Cycles With Dominant Sporophytes o Gametophytes reduced over time sporophytes more prominent 0 Transport in Xylem and Phloem o Xylem conducts water and minerals by tube shaped cells called tracheids Cells strengthened by polymer lignin o Phloem cells in tubes transporting sugars amino acids and organic products 0 Evolution of Roots 0 Roots organs that absorb water and nutrients from the soil contain vascular tissue provide support and anchor o Evolved from lowest portions of stem below the ground in sporophytes Evolution of Leaves 0 Increase surface area to get more sunlight 0 Two groups Mircophylls small spine shaped leaves Megaphyllslarger leaves supported by highly branched vascular system Sporophylls and Spore Variations o Sporophylls modi ed leaves that bear sporangia Fern Sporophylls form sori clusters of sporangia on undersides of Sporophylls Lycophytes and most gymnosperms form strobili conelike structures of sporangia o Homosporous one type of sporangium producing one type of spore that develops into a bisexual gametophyte o Heterosporous two types of sporangia make two types of spores Megasporangia and megasporophylls make megaspores that develop into female gametophytes Microsporangia and microsporophylls make male gametophytes Classi cation of Seedass Vascular Plants 0 Two types of seedless vascular plants Phylum Lycophyta and Phylum Monilophyta o Lycophyta club mosses spike mosses and quillworts o Monilophytes ferns horsetails and whisk ferns o Phylum Lycophyta o Grow on tropical trees nonparasitic use them as a substrate 0 Some grow on the ground 0 Gametophytes above ground are photosynthetic below use symbiosis with fungi 0 Club and spike mosses clustered into strobili quillworts live in aquatic areas 0 Club mosses homosporous spike mosses and quillworts are heterosporous o Phylum Monilophyta O 0 More complex structures in sporophytes on the bottom of their leaves they have sporangia which produce spores by meiosis gtspores undergo mitosis to produce multicellular haploid gametophytesgtproduces Archegonium eggsgt produces antheridium sperm Growth of embryo and young plant is not independent Ferns have Megaphylls Sporophytes live separately when gametophyte die Homosporous Horsetails Homosporous Stems contain joints Whisk Ferns Sporophytes have stems but no roots Yellow knobs no leaves consist of three sporangia Signi cance of Seedass Vascular Plants 0 Early forests in Carboniferous and Devonian periods contributed to large drops in carbon dioxide levels made glaciers and coal
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