Download gymo and angio plants 2

Gymnosperms and Angiosperms
AP Biology
2007-2008
Overview
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Gymnosperm: conifers
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Cones & naked seeds
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First seed plants
 Gymnosperm: conifers

Have vascular tissue
 ROOTS, XYLEM, PHLOEM

heterospory
 Separate male/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
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What is heterospory?
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Pollen Grain
 Male gametophyte
is carried through
a pollen grain
 Pollen eliminated
the requirement
for water for
fertilization

spread through
wind & animal
Where can
conifers live?
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What are seeds?
 Produced when egg and sperm become
fertilized.
 For gymnosperms

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Contain baby sporophyte (2n) and food
(n)
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Advantages of Microscopic
Gametophytes
 Gametophytes can live inside the
sporophyte and be protected from
environmental stresses
protected from UV radiation
 protected from drying out
 Get food from sporophyte

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Angiosperm: flowering plants
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First flowering plants
 Angiosperm: flowering plants


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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Flower
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What the parts of the flower do?
 Modified shoot with 4 rings
of modified leaves
sepals
 petals
 Stamen (male)

 Filament
 anther

Carpel (female)
 Stigma
 style
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Double Fertlization
 See step 5:
one sperm (n) fertilizes the egg (n)
forming a zygote (2n)
 the other fertilizes the central cell (2n)
form endosperm (3n) which is food
supply

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Seed & Plant embryo
 Seed offers…



protection for
embryo
stored nutrients
for growth of
embryo
Are spread by
wind, insects, or
birds. NO NEED
FOR WATER
cotyledons = “seed” leaves,
first
leaves of new plant
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endosperm
(3n)
cotyledons
embryo (2n)
seed coat
Monocots & dicots
 Angiosperm are divide into 2 classes

dicots (eudicot)
 2 cotyledons (seed leaves)
 leaves with network of veins
 woody plants, trees, shrubs, beans

monocots
 1 cotyledon
 leaves with parallel veins
 grasses, palms, lilies
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Comparisons Between Gymnosperm
Angiosperms
 POLLINATION:
Angiosperms rely on plants and animals-this helped with the
evolution of flowers to entice the insects and animals to spread
their pollen
 Gymnosperms rely on wind as their main source of pollination,
which leads to trees with very similar genotypes in a very
concentrated area (think of dense pine forests)
TIME FROM POLLINATION TO FERTILIZATION
 Angiosperms pollinate and fertilize almost simultaneously
 Gymnosperms-pollen can often sit for a period of up to 15 months
or more before fertilization occurs. The pollen grains sit within the
cone for this time.
DOUBLE FERTILIZATION
 Angiosperms-one sperm fertilizes the egg while the other combines
to form an endosperm
 Gymnosperms-No double fertilization
FRUIT
 Angiosperms-produce fruit-evolve with mammals to entice animals
to spread seeds
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 Gymnosperms-seeds without fruit

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
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