Angiosperm Reproduction

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Angiosperm Reproduction and Life Cycle Ch. 19
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Life Cycles The Alternation of Generations
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Non-vascular plants mosses, liverworts, hornworts
Spores are released w/ mitotic divisions the
gametophyte develops
Gametophytes produce gametes (sperm and
egg) Fertilization creates zygote With mitotic
divisions the sporophyte develops Sporophytes
remain dependent upon the gametophytes.
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Vascular Seedless Plants (club mosses, ferns,
horsetails)

• -Spores are released w/ mitotic divisions the
  gametophyte develops
• -Gametophyte remains independent of sporophyte
• Gametophytes produce gametes (sperm and egg)
• Fertilization creates zygote
• With mitotic divisions the sporophyte develops
• Sporophytes become independent, gametophytes die
  off

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Sporophylls contain sporangia
horsetails
Club mosses
A sporangium at base of a sporophyll
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Sporophylls contain sporangia
ferns
Sprangia on the underside of a leaf (technically
sporophyll)
Sprangia protected in reduced, scale-like
sporophylls of some ferns
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Seed plants sporophylls still contain sporangia
Pine gymnosperm
Cycad gymnosperm
Spores are retained Gametophyte is dependent upon
sporophyte Megagametophyte embryo sac (7
cells) Microgametophyte pollen grain (2 cells)
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Carpel a megasporophyll that is folded and fused
(ovary)
ovules
ovary formed by fused carpels
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The Flower

• Sporophylls
• Stamens (Androecium)
• Carpels/Pistils (Gynoecium)
• Sporangia
• -microsporangium
• -megasporangium

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Microsporangium (pollen sac) microsporogenesis ?
microspore microgametogenesis ?
microgametophyte (pollen)
Anther x-section
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Microgametophyte pollen grain
immature
Pollen walls - outer (exine) sporopollenin
- inner (intine) pectin, cellulose
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(No Transcript)
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Mature microgametophyte
tube cell
sperm cells
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Megasporangium Megasporogenesis ? megaspore
Megagametogenesis ? megagametophyte (embryo sac)
Carpel is megasporophyll
Megasporophyll contains 1 or numerous
megasporangia (ovules)
Megasporangia each contain a megasporocyte
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Ovule
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megasporocyte
meiosis
4 haploid megaspores (3 aborted)
Remaining megaspore undergoes 3 mitotic
divisions (8 haploid nuclei)
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Megagametophyte embryo sac (7-celled, 8-nucleate)
nucellus (2n)
integument (2n)
egg (1n)
1 of the 2 polar nuclei (the others obscured
from view) (1n 1n)
2 synergids (1n)
3 antipodals (1n)
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Double fertilization
2n zygote ? embryo
2n integuments ? seed coat 2n ovary/carpel ? fruit
3n endosperm
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Angiosperm Life Cycle
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Angiosperm Life Cycle
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Angiosperm Life Cycle
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Angiosperm Life Cycle
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Angiosperm Life Cycle
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Angiosperm Life Cycle
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• Characteristics of Angiosperms
• Extremely reduced gametophyte
• Indirect pollination
• Double fertilization
• Ovules/seeds contained within carpels
• Carpels develop into fruit