Plant Diversity: Colonization of Land

Chapter 29: Plant Diversity I - How Plants Colonized Land

• Note cards are recommended for derived traits, the four traits for what makes a plant a plant, gametophyte/sporophyte, antheridium/archegonium and seedless vascular and nonvascular plants.

• Green algae called charophytes, within the phylum Archaeplastida, are the closest relatives of land plants

• Similarities between algae and plants are examples of analogous structures

  • Blade equals leaves.
  • Stipe equals stem.
  • Holdfast equals roots

• Alternation of Generation has two portions: meiosis and fertilization.

• Meiosis leads to the production of gametes which come together by fertilization to make a zygote.

• The process includes haploid in some phases and diploid in others.

• Chapter objectives include describing the evolution of land plants from algae, high points of life cycles of nonvascular plants, and traits of seedless vascular plants along with related examples.

• Earth is estimated to be 4.5 billion years old.

• Cyanobacteria and protists likely existed on land 1.2 billion years ago.

• Small plants, fungi, and animals emerged on land around 500 million years ago.

• Plants supply oxygen and are the ultimate source of food eaten by land animals.

• Without plants, other organisms would be unlikely to survive.

• Understand that land plants are not descended from modern charophytes, but they share a common ancestor.

• They are arranged on the phylogenetic tree to show this relationship.

• Fossil evidence indicates that plants were on land at least 475 million years ago.

• Land plants can be informally grouped based on the presence or absence of vascular tissue.

  • Vascular tissue consist of cells joined into tubes that transport water and nutrients, vascular plants have this.

• Nonvascular plants are commonly called bryophytes.

  • Bryophytes are not a monophyletic group.

Derived Traits of Plants

• Four key traits appear make a plant a plant:

  • Alternation of generations
  • Walled spores produced in sporangia
  • Multicellular gametangia
  • Apical meristems
    • Localized regions of cell division (aka growth) at tips of roots and shoots

• Nonvascular plants (bryophytes), then Seedless vascular plants, Angiosperms, and Gymnosperms.

Alternation of Generation

• Adult plants alternate between two multicellular stages, a reproductive cycle called alternation of generations.

• The gametophyte is haploid (n) and produces haploid gametes by mitosis.

  • Gametes equal sex cells

• Fusion of the gametes gives rise to the diploid sporophyte (2n), which produces haploid spores (n) by meiosis.

• Know that spores grow (by mitosis) into gametophytes, which produce gametes.

• Know that two gametes come together to produce a diploid zygote which grows (by mitosis) into a sporophyte,

• Know that meiosis is the generation of haploid spores, and understand that this process is a cycle

• The sporophyte produces spores in organs called sporangia.

• Spores are haploid, and result when diploid cells called sporocytes (2n) undergo meiosis

  • These spores grow to form a gametophyte through mitosis

• Gametes (both egg and sperm) are produced within organs called gametangia.

  • Gametangia called archegonia produce eggs and are the site of fertilization
    • The singular form is archegonium
  • Gametangia called antheridia produce and release sperm.
    • The singular form is antheridium

• Sperm travels to archegonium and fertilizes the egg which develops into a diploid embryo.

• Bryophytes are represented today by three phyla of vascular tissue, roots, and true leaves

  • Liverworts, phylum Hepatophyta
  • Mosses, phylum Bryophyta
  • Hornworts, phylum Anthocerophyta

• These groups are thought to represent the earliest lineages to diverge from the common ancestor of land plants.

Seedless Vascular Plants

• Ferns and other seedless plants were the first to grow tall.

• Bryophytes were prominent types of vegetation during the first million years of plant evolution

• The earliest fossils of vascular plants date to 425 million years ago

• Vascular tissue allowed these plants to grow tall.

• Seedless vascular plants have flagellated sperm and are usually restricted to moist environments.

• Vascular plants make up 96% of known species .

• They have the well developed transport system and true roots, stems and leaves.

• There are two clades of seedless vascular plants

  • "The Lycophytes”: Phylum Lycophyta Consist of mainly club mosses Look like bigger, sturdier mosses. Have leaves are called microphylls
  • "The Monilophytes”: Phylum Monilophyta Consist of mostly ferns and their relatives Have large, complex leaves called megaphylls

Significance of Seedless Vascular Plants:

• The ancestors of modern lycophytes and monilophytes grew to great heights, forming the first forests.
• Increased growth and photosynthesis removed CO₂ from the atmosphere and contributed to global cooling.
• Decaying plants from these forests eventually became coal.

Chapter 30 Concept 1: Seeds and Pollen as Adaptations for life on land

• Note cards are recommended for pollination, gymnosperm, angiosperm, structures of flower and function, and four main traits of seed plants

• Seed plants originated about 360 million years ago.

• A seed consists of an embryo and nutrients surrounded by a protective coat

• Seeds can disperse over long distances by wind or other means.

Common Characteristics of Seed Plants

• Reduced gametophytes

• Heterospory

• Ovules

• Pollen

• Seedless plants demonstrate homospory.

  • This is production of a single kind of sperm that forms a bisexual gametophyte

• The gametophytes of seed plants are microscopic.

  • They obtain nutrients from the parent plant

• Heterospory: The Rule Among Seed Plants

  • The early ancestors of seed plants were likely homosporous seedless plants, but seed plants have evolved to be heterosporous.
    • Seed plants produce a single kind of sperm that forms a bisexual gametophyte
  • Megasporangia produce a single megaspore that produces female gametophytes
  • Microsporangia produce many microspores that gives rise to male gametophytes

• An ovule consists of a megasporangium, a megaspore, and one or more protective integuments.

  • Gymnosperm megasporangia have one integument
  • Angiosperm megasporangia usually have two integuments

• Seed plants uniquely retain the megasporangium and megaspores within the sporophyte

  • Inside the ovule, the female gametophyte develops from the megaspore and produces eggs.

• Microspores develop into pollen grains, which contains the male gametophyte enclosed within the pollen wall

• Pollination is the transfer of pollen to the part of a seed plant containing the ovules.

  • If a pollen grain germinates, it produces a pollen tube that discharges two sperm (double fertilization) into the female gametophyte within the ovule

• A seed develops from the whole fertilized ovule

• A seed sporophyte embryo, along with its food supply, packaged in a protective coat.

• Seeds include some evolutionary advantages over spores

  • They may remain dormant for days to years, until conditions are favorable for germination.
  • Seeds have a supply of stored food.
  • They may be transported long distances by wind or animals.

• Two types of Vascular Seed Plants include Gymnosperms and Angiosperms

• Gymnosperms means "naked seeds."

  • The seeds usually form cones.
  • There are four phyla
  • Cycads-woody plants that look like palms
  • Ginkgo with only one species: Ginkgo biloba
  • Guetophytes
  • Conifers, the most diverse gymnosperms including pines, firs and redwoods

• Angiosperm seeds are found in fruits, which are mature ovaries.

Chapter 30 Concept 2: Reproductive Adaptations of Angiosperms

• Angiosperms are seed plants with reproductive structures known as flowers and fruits.

• They are the most widespread and diverse of all plants.

  • However, this is a very young phylum, and compose ~90% of all plant species

• A flower is a specialized angiosperm structure specialized for sexual reproduction.

• Many species are pollinated by insects or animals, while some species are wind-pollinated.

• A flower is a specialized shoot with up to four types of modified leaves called floral organs:

  • Sepals, which enclose the flower
  • Petals, which are brightly colored and attract pollinators
  • Stamens, which produce pollen or male organ
    • This consists of pollen (aka MICROspores), and a stalk and a filament
  • Carpels, which produce ovules or a female organ.
    • Ovules aka MEGAspores

• A carpel consists of:

  • An ovary at the base
  • Style leading up to a stigma, where pollen is received -If a fertilized ovary turns into a seed, it may turn into fruit.

• Angiosperm Life Cycle

  • flower of the sporophyte consists of both the male structures as well the female structures.

• Male gametophytes are produced by the microsporangia of anthers, which are contained within the pollen grains

• female gametophyte develops, or embryo sac, within an ovule contained within an ovary at the base of a stigma

• most flowers include certain mechanisms to ensure that there is cross-pollination between different flowers from the same species Pollen grain lands on a stigma, it germinates, and begins tube of the male gametophyte grows to the ovary.

• Double fertilization occurs when tube discharges two sperm to the female gametophyte located within that ovule.

• One sperm can fertilize the egg; while others combine by having two nuclei in the central cell in cells in initiating storage. -Triploid edosperm the developing embryo.

• Within a seed that consists embryo; which has developed from the seed leaves known.

Chapter 31, Concept 1: Fungal Structures

• Cards are recommended for budding, mycorrhizae, hyphae, plasmogamy, and karyogamy

• Objectives

  • Be able to identify the main fungal anatomy
  • Know how fungi reproduce.

• Understand the fungal phylogeny.

• Fungi are heterotrophs that feed by absorption.

  • Despite their diversity, fungi share key traits, most importantly the way in which they derive nutrition.

• Fungi represent a monophyletic group containing heterotrophs; that often help absorb nutrients outside their body.

  • Digest then eat

• Fungi exhibit diverse lifestyles.

  • Decomposers
  • Parasites
  • Mutualists

Body Structure:

• Most common body is multicellular filaments.

• There are also single cells also known as yeast.

• Multicellular species are made up of small filaments; also which include tubular wall cells known to contain hyphae.

• Morphology with multicellular fungi; helps improve their ability in the absorption nutrition..

  • Fungi consist mainly with mycelia; which includes mat.

• Cells with can contain strong with a flexible containing polysaccharide with arthropods

• Most fungi contains hyphae divided as cells which consist of porta’s cells movement with organelles.

• Mycorrhizae; are well beneficial with relationship to the roots/fungi.

  • Mycorrhizal fungi; can help often deliver well minerals within plants .
  • Vascular plants often have microhizae.
  • Colonizing soils mostly occur by cells as spores.

Concept 2: Fungal Reproduction

• Fungi production:spores though sexual / asexual life

• Fungi often propagate mostly with producing vast mainly numbers spore weather

• Fungi well produce spores many with different cycle

• Individual who reproduce sexual with also partner with

Sexual Reproduction:

• Usually well helps provide a large genetic section and relation

• Fungi are very short

• Sexual production

• Fungi with molecuels

• Plasmogamy: is the of joining of cytoplasm*

• Fusion with karyogamy

genetic reproduction. Sporse by mitosis.

• Asexually
• Yeast single cells
• Asexual with butting production

Concept 3: How fungi fit into the phylogenetic Tree

• Animals are closer to fugi. -Animals relation with photist family .
• Evolves with a cell- DNA*
• -5 phyla:* -Chytrids -Zygomycetes -Glmeronyete -Ascommyyetes (sac Fungi) -Basidimicyetes Have fruity bodies Important decompose