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Seed Development
- Ovules are produced inside an integument
- Integument--> seed coat (post-fertilization)
- Ovule is the femail sporangium and contents
- First megaspore, then female gametophyte
- Femail gametophyte produces the egg
- Pollen fertilizes the ovule
- Enters through the micopyle of integument
- Carries sperm to the egg nucleus
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Vascular seed plant advantages
- Embryo is protected from environment
- Ex: temperature, dehydration
- Seed coat can be modified
- To carry embryo away from parent
- Ex. Seed Wings
- To act a food source for animal vector
- Fruit-like seed coats
- Seed usually contains food supply
- To nourish embryo
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Gymnosperms
- Gymnosperm=Naked seed
- Seeds are not surrounded by true fruit
- Seeds often produced on cones
- Groups include:
- Cycads, Conifers, Gingkos, Gnetophytes
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Conifer Life Cycle
- Mature tree is the sporophyte
- Cones contain sporangia and spores
- Seperate male and female cones
- male & female develop inside spore walls
- Male gametophytes released
- Pollen grains will produce sperm
- Female gametophytes stay in cones
- Eggs fertilized and seed produced
- Seeds germinate to produce sporophyte
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Angiosperms
- Flowering Plants
- The most derived group of plants
- Flower is a modified shoot that can have:
- Sepals-protect the flower in the bud
- Petals- often attract pollinator animals
- Stamens- male, another produces pollen
- carpels- female, stigma receives pollen, ovary contains ovules.
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Life Cycle of Angiosperms
- Sporophyte is the visible plant with flowers
- Spores produced in another male and ovary female
- Gametophytes develop inside spores
- Male gametophytes are released (pollen)
- Female gametophytes retained in ovary
- Sperm from pollen fertilizes egg in ovary
- Embryo forms inside seed coat
- Ovary develops into fruit containing seed
- Seed germinates to produce sporophyte
- Have double fertilization
- One sperm fertilizes egg to create zygote
- One sperm leads to formation of endosperm
- Endosperm is nutritive tissue inside seed
- Fruit adaptations help seed dispersal
- Can act as food source for animal vectors
- May have wings for wind dispersal
- Some are burrs to hitchhike on animals
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Monocot (1) vs. dicot (2) in angiosperms
- Number of cotyledons (embryonic leaves - 1 vs. 2)
- Leaf venation (parallel vs. net)
- Number of flower parts (3's vs. 4's and 5's)
- Number of pollen pores (1 vs. 3)
- Stem anatomy (no pith vs. pith)
- Root morphology (fibrous vs. taproot)
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