Biology of Plants

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Chapter 12 Part Two Systematics The Science of
Biological Diversity
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Development of classification

• A. Until relatively recently organisms were
  classified as either plants or animals and two
  kingdoms were recognized. 
• 1. Non-motile autotrophs were placed in the plant
  kingdom
• 2. Motile heterotrophs were placed in the animal
  kingdom

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Many organisms didnt fit

• 1. Euglena is a unicellular, motile autotroph
• 2. Fungi (mushrooms and molds), traditionally
  classified as plants, are non-motile heterotrophs

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Technology led to better classifying cells

• 1. Prokaryotes (bacteria) - lack nuclei,
  organelles, flagella, chromosomes,
  multicellularity and sexuality
• 2. Eukaryotes (nearly all other organisms) -
  have nuclei, organelles, flagella, DNA
  associated with histone proteins to form
  chromatin/chromosomes, sexual reproduction and
  most are multicellular

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Thomas Whitaker (1969)

• 5 kingdom system
• All Prokaryotes were placed into a single
  kingdom (Monera i.e. bacteria) and the Eukaryotes
  were placed into four kingdoms Plantae, Fungi,
  Animalia and Protista (unicellular)

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Three domains

• A. Recent genetic and molecular investigations
  have demonstrated that there are two major groups
  of prokaryotes. They differ radically in the
  composition of their cell walls, membrane lipids,
  ribosomal RNA, and a variety of other biochemical
  features

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• Therefore, our text recognizes three domains
  above the rank of kingdom

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1. Domain Bacteria

• - prokaryotes with muramic acid in cell walls.
  Majority of bacteria plus cyanobacteria ("blue
  green algae")

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2. Domain Archaea (ancient bacteria)

• - prokaryotes that lack muramic acid in cell
  walls. Many inhabit "harsh" environments.
  Includes methane producers, extreme halophiles,
  extreme thermophiles, acidophiles and one group
  which lacks cell walls

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3. Domain Eukarya

• all eukaryotes, four kingdoms
• Animalia
• Plantae
• Fungi
• Protista

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Kingdom Animalia (Animals)

• - motile, multicellular, lack plastids and cell
  walls, heterotrophic via ingestion, sexual
  reproduction

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Kingdom Plantae (Plants)

• - nonmotile, multicellular, plastids and
  autotrophic via photosynthesis, cell walls made
  of cellulose, adapted for life on land, mostly
  sexual reproduction. 
• "Algae" are not included in this kingdom

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Kingdom Fungi (Mushrooms and Molds)

• - nonmotile, filamentous, lack plastids, cell
  walls are made of chitin, heterotrophic via
  absorption of nutrients from dead (saprophytic)
  or living (parasitic) matter. Virtually all are
  multicellular except yeast. Both sexual and
  asexual reproduction

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Kingdom Protista

• - lack multicellularity. Heterogeneous
  assemblage of unicellular, colonial and
  multicellular Eukaryotes that do not have the
  distinctive characters of plants, animals or
  fungi. 
• They have various types of reproduction from
  simple cell division through sexual, and various
  types of nutrition
• Includes all groups previously called protozoa as
  well as all the algae except blue greens. Also
  includes some organisms previously called fungi

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Origin of a Photosynthetic eukaryotic cell from a
heterotrophic prokaryote
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Endosymbiosis in Vorticella
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Autotrophic endosymbiotic alga
Electron Micrograph of a Vorticella
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Fungi

• Lichen
• Fungus
• mushroom

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Fungi- red blanket lichen Florida swamp
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White coral fungus Clavariacea
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Mushrooms genus Mycena Rainforest Peru
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Earthball Scleroderma citrinum
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Protist

• Plasmodium slime mold
• Postelsia palmiformis- sea palm
• Volvox- green alga
• Fauchea- red alga
• Pennate diatom

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Plasmodium slime mold
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Postelsia palmiformis- sea palm
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Volvox- green alga
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Fauchea- red alga
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Pennate diatom
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Plants

• Three phyla of bryophytes
• Sphagnum (peat moss)
• Marchantia (thallose liverworts)
• Club moss
• Seven phyla of vascular plants
• Wood Horsetail
• Maidenhair fern
• Dandelion Taraxacum officinale
• Strawberry cactus
• Foxtail barley
• Cymbidium orchids
• Sugar pine

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Bryophytes
Sphagnum (peat moss)
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Marchantia (thallose liverworts)
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Club moss
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Vascular plants
1. Wood Horsetail
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2. Maidenhair fern
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3. Dandelion Taraxacum officinale
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4. Strawberry cactus
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5. Foxtail barley
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6. Cymbidium orchids
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7. Sugar pine
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The principal types of Life cycles

• First eukaryotic organism probably haploid and
  asexual
• For plants the stage was set for diploidy
• Reproduction is primarily sexual
• Alternating haploid and diploid generations
• Unifying character of the plantae is the presence
  of a embryo during the sporophytic phase of the
  life cycle-- thus embryophyte synonymous with
  plant

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• Zygotic meiosis- Fungi, some algae- two haploid
  form diploid then split to form haploid again
• Gametic meiosis
• Sporic meiosis

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Give rise to gametes by differentiation
Divide by mitosis
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• Zygotic meiosis
• Gametic meiosis- by accident some of these
  cells undergo mitosis with a delaymeiosis
• Sporic meiosis

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4 haploid
Green/brown
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• Zygotic meiosis
• Gametic meiosis
• Sporic meiosis- results in the production
• Of spores, not gametes, spores undergo mitosis
• And produce multicellular haploid organisms these
  haploid organisms can then produce gametes that
  in turn fuse to form Zygote

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Spores Dont act as gametes and Undergo Mitotic
division
produce
4 haploid
Differentiate to form Sporophyte