Chapter 29 and 30: Plants

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Chapter 29 and 30 Plants Objectives -Understand
that land plants evolved from green algae -Mosses
and other nonvascular plants have life cycles
dominated by gametophytes -Ferns and other
seedless vascular plants were the first plants to
grow tall -Seeds and pollen grains are the key to
success for land plants -Gymnosperms bear naked
seeds (cones) -Reproductive adaptations of
angiosperms include flowers and fruit
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• Morphological and Molecular data suggests land
  plants evolved from green algae (Charophytes)
• Morphological
• Rossete shaped cellulose synthesizing proteins in
  plasma membrane
• Peroxisome enzymes that help minimize loss of
  organic products of metabolism from
  photorespiration
• Flagellated sperm
• Formation of a phragmoplast during cell division
• Genetic Sampling also indicates similarities

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2. Production of protective spores
Adaptations or derived characteristics that
allowed plants to move to land.

• 1. Alternation of Generations
• -Has a multicelluar haploid and diploid organisms
• -Plants are called embryophtes due to the
  embryonic activity in the female gametophyte
• - Analogous to mammals

4. Use of an Apical meristem for elongation
3. Multicellular Gametangia (1n)
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Current Understanding of plant evolution
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Bryophyte refers to all Nonvascular
plants -Gametophytes are longer and larger then
Sporophyte
Horwort
Liverwort
Mosses
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Seedless Vascular Plants -Sporophyte
dominant -Contain Xylem, which brings water and
minerals up from the roots Allows for
strength in stem growing tall -Contain Phloem
for transport of organic compounds
Sporophylls -Modified leaves that contain
Sporangia -Homospores one type of
spore -Heterospore male (microspore) and female
spore (megaspore)

• Leaves divided into
• Microphylls (smalll)
• Megaphylls (large extensive leaves)

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Seedless Vascular Plants
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The importance and evolutionary significance of
seeds as a derived characteristic

• 1. 2n Embryo with its food supply
• Means the embryo can survive away from mother
  plant
• Analogous to a detachable womans womb
• Dispersed in a variety of ways
• Contributions to human society
• Hunter/Gatherer
• to
• Settlers using agriculture

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Immergence of Seed plants

1. Reduced Gametophyte stage Allows for protection
   of the gametophytes within the sporangia of the
   sporophyte great success in seeded plants
2. Contain heterospores (Male and Female)
3. Seeds have advantages over spores (More
   protection, Food source, Can remain dormant
   longer, Stored food can help in germination)

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Development of seeds and pollination

1. Female (Megasporangium) is covered by a thin
   layer called integument
2. Megasporangium undergoes Meiosis and produces a
   Megaspore
3. Pollen is produced in a mircospore
4. Pollen doesnt need water to swim in like
   Flagellated sperm of seedless plants (Wind or
   hitch hike)

• Female Gametophyte grows
• Male Gametophyte is in the pollen grain
• 3. Pollination occurs (Pollen (1n) enters
  through an opening of the integument and
  fertilizes the egg
• After fertilization the integument turnes into
  the seed coat
• Embryo or new sporophyte begins to form

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• Gymnosperms
• - Naked seeds (No Fruit)
• -Four Gymnosperm Phyla
• Ginkgophyta
• Coniferophyta
• Cycadophyta
• Gnetophyta

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Pollination occurs when pollen attaches to the
Megaspore and germinates forming a pollen tube
(digests its way through the Megasporangium)
Conifers have both pollen and ovulate cones
While pollen tube extends the Megaspore undergoes
meiosis
Microspores produce pollen grains that contain
the gametophyte
Usually takes about a year from pollination to
seed and only one embryo usually survies
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Stamen produce microspores which turn in to pollen
Carpel produces megaspores
Angiosperms are flowering plants
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Fruits -Fruits are the ovary with the fertilized
seed inside -Protect and aid in dispersion
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Some flowers self pollinate while most have
mechanisms to cross pollinate
Double fertilization produces endosperm or
nutrients -Possible reason is to synchronize
development of food sources and seed
4 megaspores are formed with one surviving
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Monocots
Eudicots
Basil Angiosperms
Magnoliids