gymnosperm & angiosperm - brookings school...
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28
2004-2005AP Biology
Gymnosperm: conifers Characteristics
vascular heterospory
male vs. female gametophytes seeds
naked seeds (no fruit) pollen
contain male gametophyte life cycle dominated by sporophyte stage
coniferous trees you are familiar with are diploid reduced (microscopic) gametophyte reduction of gametophyte protects delicate egg
& embryo in protective sporophyte protected from drought & UV radiation
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2004-2005AP Biology
Evolutionary trends in land plants Reduction in gametophyte
bryophytes pteridophytes gymnospermangiosperm
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2004-2005AP Biology
Gymnosperm (Pine) life cyclefemale
gametophytein cone
malegametophyte
in pollen
sporophytein seed
meiosis meiosis
fertilization
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2004-2005AP Biology
Angiosperm: flowering plants Characteristics
vascular heterospory
male vs. female gametophytes flower
specialized structure for sexual reproduction seeds within fruit pollen life cycle dominated by
sporophyte stage trees & bushes you are familiar
with are diploid reduced (microscopic)
gametophyte
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2004-2005AP Biology
Flower Modified shoot with 4 rings of
modified leaves sepals petals stamens
male carpals
female
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2004-2005AP Biology
Angiosperm life cycle
femalegametophyte
in ovary
malegametophyte
in pollen
sporophytein seed
fertilization
45
2004-2005AP Biology
Angiosperm Flowering plants
flowers and fruit monocots
1 seed leaf leaves with parallel
dicots 2 seed leaves leaves with net-like venation
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2004-2005AP Biology
Evolutionary trends Vascular tissue
tubes for transport non-vascular
bryophytes - mosses vascular
pteridophytes - ferns gymnosperm - conifers angiosperm - flowering plants
Evolutionary advantage? adaptation to dry terrestrial conditions allows increased size (think trees!)
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2004-2005AP Biology
Evolutionary trends Sperm dissemination
flagellate (swimming) sperm bryophytes - mosses pteridophytes - ferns
wind-blown or animal-carried pollen gymnosperm - conifers angiosperm - flowering plants
Evolutionary advantage? adaptation to dry terrestrial conditions
eliminated water requirement for fertilization
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2004-2005AP Biology
Evolutionary trends Seeds
seedless plants bryophytes - mosses pteridophytes - ferns
seed plants gymnosperm - conifers angiosperm - flowering plants
Evolutionary advantage? adaptation for reproduction in diverse
terrestrial environments resistant, dispersal stage
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2004-2005AP Biology
Evolutionary trends Reduction of gametophyte
gametophyte dominant bryophytes - mosses
sporophyte dominant, free living gametophyte pteridophytes - ferns
sporophyte dominant, reduced gametophyte gymnosperm - conifers angiosperm - flowering plants
Evolutionary advantage? adaptation for reproduction in diverse
terrestrial environments reduction of gametophyte protects delicate egg & embryo
in protective sporophyte protected from drought & UV radiation
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