Seed Plant Quiz PDF

Chapter 26 : The Seed Plants: Gymnosperms & Angiosperms Be able to: Describe and explain significance of the key reproductive adaptations in seed plants. Describe the characteristics and diversity of the gymnosperms. Explain how their adaptations have made them successful. Describe the characteristi...

Chapter 26 : The Seed Plants: Gymnosperms & Angiosperms Be able to: Describe and explain significance of the key reproductive adaptations in seed plants. Describe the characteristics and diversity of the gymnosperms. Explain how their adaptations have made them successful. Describe the characteristics and diversity of the angiosperms. Explain how their adaptations have made them successful. warmer again & dry Evolutionary History of Seed Plants cooler & drier wet & warm flowering plants begin to diversify flowering plants appear Age of Dinosaurs cycads & conifers dominate landscape gymnosperm forests replace lycophyte & fern forests first gymnosperms forests of seedless vascular plants dominate swampy land first seed plants first vascular plants first land plants Seeds and Pollen as an Evolutionary Adaptation to Dry Land Female gametophyte: The egg Endosperm-producing cell (supports the growth of the embryo) ▪ Embryo – produced from the diploid zygote, grows into the sporophyte when seed germinates ▪ Seed - offers the embryo protection, nourishment, and a mechanism to maintain dormancy, allow plants to disperse the next generation through both space and time Male gametophyte: Pollen grains (contain the sperm of the plant) Protected from dessication Not dependent on water to reach the female organs Gametophyte-sporophyte relationship in seedless plants dispersed spore grows into → dispersed spore grows into → Reproductive Adaptations of Seed Plants (Reduced Gametophyte) megaspore grows into → microspores grow into → Reproductive Adaptations of Seed Plants Reduced & Retained Gametophytes Seed plants are heterosporous: megaspores (grow into female gametophytes) microspores (grow into male gametophytes) Both gametophytes mature within sporangia highly reduced in size protected from drying & UV Reproductive Adaptations of Seed Plants Ovule = integument + megasporangium + megaspore Megaspore germinates within ovule, develops into tiny female gametophyte – produces egg which will eventually be fertilized Reproductive Adaptations of Seed Plants Seed Develops from fertilized ovule includes: embryo, food supply, seed coat Pollen grains: male gametophyte surrounded by pollen wall (partly secreted by sporophyte) Capable of long dispersal, tough & resistant, & sperm nuclei does not require external H2O for fertilization Sporopollenin in the pollen wall protects pollen grains Pollination: transfer of a pollen to a part of the seed plant that contains the ovule Pollen grain germinates Pollen tube Sperm discharged into female gametophyte Gymnosperms Characteristics: ‘Naked’ seeds (partially sheltered by sporophylls) Separate male and female gametes Pollination by wind Tracheids Life cycle involves alternation of generations Reduced male and female gametophytes Dominant sporophyte All are heterosporous Male and female reproductive organs can form in cones or strobili Monoecious or Dioecious Life cycle of a Conifer (gymnosperm) Five Phyla of Extant Seed Plants Coniferophyta Cycadophyta Gnetophyta Ginkophyta Anthophyta Gymnosperms No o eri Naked seed o i ers y ads i Ginkgos kos Angiosperms lo eri o ered seed all o eri pla ts Gymnosperms: Coniferophyta Phylum Coniferophyta – conifers Most diverse gymnosperms today “ o e-bearers” ▪ male pollen cone (sperm not motile) ▪ female ovulate cone dominate high altitudes & latitudes in N. Hemisphere most are evergreen with needle-like leaves examples include: pine, fir, spruce, sequoias Gymnosperms: Cycadophyta Phylum Cycadophyta – cycads fern-like or palm-like fronds radiate from central stem central female & male cones with flagellated sperm beetles are involved in pollination of some cycads Gymnosperms: Ginkgophyta Phylum Ginkgophyta - ginkgos one extant tree: Ginkgo biloba herbal medicine with flagellated sperm flagellated sperm female sporophylls, not cones male sporophylls, in strobili unique fan-shaped leaf & veins Gymnosperms: Gnetophyta Phylum Gnetophyta: gnetophytes 3 distinct genera: Gnetum in tropics, Welwitschia in SW Africa deserts, Ephedra in U.S. deserts male & female strobili; sperm not motile Ephedra - herbal medicine (Ephedrine) Angiosperms - > 300,000 spp., almost every habitat Angiosperms Stigma Stamen Anther Key innovations are flowers & fruits Carpel Style Filament Ovary 1. Flower – structure specialized to facilitate sexual reproduction ▪ Success mainly due to coevolution with pollinators Petal Sepal Ovule Sepals – green leaf-like appendages that enclose the rest of the flower Petals – brightly colored appendages that aid in attracting pollinators 1. Stamen: Filament – stalk that holds up pollen-producing sac Anther – terminal sac that produces pollen 1. Carpel (aka “pistil”): Stigma – sticky tip of carpel that receives pollen Style – long tube leading from stigma to ovary Flower structure Ovary – structure at base of the carpel that produces ovules Ovules develop into seeds if fertilized Angiosperms: Life Cycle Microsporangia Male sporocytes (2n) meiosis Microspores (n) mitosis Pollen grains: 1 generative cell 1 tube cell Ovule Megasporangium Pollen grains Megasporocyte (2n) meiosis Only large megaspore survives 4 Megaspores (n) Mitosis x3 8 nuclei distributed among 7 cells of female gametophyte 3 cells at one pole become egg and 2 synergids (remaining 3 cells become antipodal cells) Center cell 2 polar nuclei Angiosperm Life cycle Angiosperms: Life Cycle Microsporangia Male sporocytes (2n) meiosis Microspores (n) mitosis Pollen grains: 1 generative cell 1 tube cell Ovule Megasporangium Pollen grains Megasporocyte (2n) meiosis Only large megaspore survives 4 Megaspores (n) Mitosis x3 8 nuclei distributed among 7 cells of female gametophyte 3 cells at one pole become egg and 2 synergids (remaining 3 cells become antipodal cells) Center cell 2 polar nuclei Angiosperm Life cycle Angiosperms: Life Cycle double fertilization with 2 sperm nuclei: one fuses with egg, forming zygote(2n) one fuses with 2* central nuclei (polar nuclei), forming endosperm (3n*) food supply in seed Female Antipodal cells Pollen *most often! 2. Fruit – mature ovary of a flower, thickens around seeds - may include some additional tissues as well - may be fleshy or dry protects seeds main function is enhancing seed dispersal Angiosperm Phylogeny and Diversity of Angiosperms Mesozoic Phylum Anthophyta Basal Angiosperms The 2 big groups of angiosperms are the Monocots (~60,000 spp.) & the Eudicots ( ~ 175,000 spp.) Mo o ots i lude or hids palms lilies rasses… Di ots i lude… lots! (oaks peas roses potatoes et.) A number of distinctive characteristics generally make Monocots & Eudicots fairly easy to distinguish True woody tissue is rarely found in monocots Eudicots can be herbaceous (non woody) or produce woody tissues – tough walled xylem cells Seed Plants & People Almost all food & beverages & spices (80% calories globally!) Wood products, including paper Fuel Fiber for clothing, rope cotton, linen, jute, hemp Secondary compounds: countless drugs & medicines perfumes latex rubber Ornamental plants Examples of Plant-Derived Medicines - Plants are a direct source of medicinal compounds - In the United States, about 25% of prescription drugs contain an active ingredient from plants No less important to organisms around the world, at least in terrestrial habitats