22.3_Seed_Plants

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1.
2.
3.
Apply Concepts Pollination is a process that occurs
only in seed plants. What process in seedless plants
is analogous to pollination
Review Describe how fertilization takes place in a
gymnosperm
Classify Make a table with two columns labeled
haploid and diploid and assign each of the
following structures from the pine life cycle to the
appropriate column: Pollen tube, Seed cone, Embryo,
Ovule, Seedling
CH 22 INTRODUCTION TO PLANTS
22.3 Seed Plants
The Importance of Seeds

Adaptations of seeds
 Plants
reproduce without open water
 Transfer of sperm by pollination
 Protection of embryos in seeds.
Seed


Plant embryo and a food supply encased in a
protective covering
Living plant within a seed is diploid and represents
the sporophyte phase.


Male gametophytes and the female gametophytes
grow and mature directly within the sporophyte
Gymnosperms
 Bear

seeds directly on the scales of cones
Angiosperms
 Bear
seeds in flowers inside a layer of tissue that
protects the seed.
Pollen Grains



Contains entire male gametophyte
Carried to the female reproductive structure by
wind or animals
Pollination
 Transfer
of pollen from the male reproductive structure
to the female reproductive structure.




Zygote contained within a seed grows into a tiny
plant- the sporophyte embryo
Embryo begins to grow under right conditions
Uses nutrients stored in the seed until it can carry out
photosynthesis on its own
Seed coat
 Surrounds
and protects the embryo and keeps the
contents of the seed from drying out.


Seed cones produce female gametophytes
Female gametophytes develop in two ovules at base
of scale.


Pollen cones produce pollen grains, which make up
the entire male gametophyte stage
One haploid nuclei will divide later to produce two
sperm nuclei.
Development Inside Seeds

Pollen tube
 Structure
containing two haploid sperm nuclei.
Development Inside Seeds



Pollen grain lands ovule
Splits open and begins to grow a pollen tube
Reaches the female gametophyte
 One
sperm nucleus disintegrates
 Other fertilizes the egg.


Fertilization produces a diploid zygote
Grows into an embryo.

Seed is an encased embryo that is ready to be
scattered by the wind and grow into a plant.

Reproduction in conifers occurs in cones from the
mature sporophyte plant.
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