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Phase of plant life cycles in
which the gametes, i.e.,
egg and
sperm, are produced. |
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The gametophyte
is haploid, that is, each cell
contains a single complete set of chromosomes, and arises from the
germination of a haploid spore. In
many lower plants, the
gametophyte phase is the dominant plant form;
The alternate phase of the plant life cycle is the
sporophyte, the
diploid plant form, with each cell
containing two complete sets of
chromosomes. The sporophyte develops from the union of two
gametes, such as an egg fertilized
by a sperm; The sporophyte is
the diploid plant form in with each
cell containing two complete sets of
chromosomes. The
sporophyte develops from the union of two
gametes, such as an
egg fertilized by a
sperm; in turn, the
sporophyte forms
spores that develop into
gametophytes. The alternation between
haploid gametophyte and diploid
sporophyte phases, known as alternation of generations, occurs in all
multicellular plants. As plants
advanced in evolutionary development, the sporophyte became the
increasingly dominant plant form and the gametophyte form has been
correspondingly reduced. In contrast to mosses, for example, in the
advanced angiosperms the male
and female gametophytes are reduced to three-celled and seven-celled
structures, respectively, found within the reproductive
organs of the familiar
flowering plant (the
sporophyte). |
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