Origins of Seeds Flashcards
are seed plants a clade
yes
what are two benefits of seeds
- provide the embryo with more protection
- water is now no longer needed to complete fertilization
what does a seed consist of
- embryo
- nutrients
- surrounding protective coat
what are 6 morphological synapomorphies for seed plants
- seeds
- pollen
- all lack antheridia
- all have ovules
- all show heterospory
- reduced gametophytes
what three things are associated with ovules
- megaspores
- megasporangia
- integument(s)
ovules in gymnosperms vs angiosperms
gymnosperms = megaspores are in a strobilus (cone)
Angiosperms = megaspores are in flowers
nutrients for embryos in gymnosperms vs angiosperms
gymnosperm = megagametophyte tissue (haploid)
angiosperm = endosperm (3n)
spores make ____
gametophytes
how do megaspores become eggs
megaspore -> mitosis -> megagametophyte ->egg
what are two key adaptions to life on land
- pollen
- seeds
dominant stage in nonvascular plants
gametophyte
sporophyte in nonvascular plants
reduced and dependent on gametophyte for nutrients
gametophyte in seedless vascular plants
reduced and independent (photosynthetic and free-living)
dominant stage in seedless vascular plants
sporophyte
gametophyte in seed plants
reduced and dependent on surrounding sporophyte tissue for nutrition
dominant stage of seed plants
sporophyte
is gametophyte micro or macroscopic in seed plants
microscopic
is gametophyte micro or macroscopic in seedless vascular plants
macroscopic
is gametophyte micro or macroscopic in nonvascular plants
macroscopic
where do gametophytes remain in seed plants
within the sporangia of parental sporophyte
what is the gametophyte in seed plants dependent on
sporophyte for nutrition
the gametophyte is retained within
sporangia walls
megasporangium- ______ - _____________
megaspore to female gametophyte
microsporangium - ____________ - _______
microspore to male gametophyte
female gametophyte develops within
an ovule
male gametophytes develop within
a pollen grain
can the pollen grain be considered the microgametophyte
yes
fertilization of ______ with ______ leads to the development of a _____
ovule with pollen grain = seed
gymnosperm megaspores have ____ integument(s)
one
angiosperm megaspores have ____ integument(s)
2
a woody cone in gymnosperms is male or female
female cone
is an ovule in a cone an angiosperm or a gymnosperm
gymnosperm (angio is in a flower)
what contains the male gametophytes
pollen grains
_____ is transfer of pollen to part of a seed plant containing ovules
pollination
what grows out of the pollen grain to deliver the sperm to the egg
pollen tube
what makes gymnosperm sperm different than angiosperm sperm
gymnosperms have sperm with Micky mouse-like ears
a seed develops from
the whole ovule
a seed is a ______ embryo with its food supply and protective coat
sporophyte
gymnosperm seeds are (haploid, diploid or both)
part diploid and part haploid
what part of a gymnosperm seed is haploid
megagametophyte
what part of a gymnosperm seed is diploid
- parental sporophyte (integument)
- new sporophyte
why is seed dormancy advantageous
some seeds can remain dormant for a very long time - allows release in optimal conditions
how can seeds be dispersed
abiotic - wind, water
biotic - animals
the archegonia in seed plants are
temporarily containing sporophyte embryos
the megaspore forms the
female gametophyte which gives new embryo food
what stage of the gymnosperm lifecycle is this
seed
what stage of the gymnosperm lifecycle is this
fertile ovule
what stage of the gymnosperm lifecycle is this
unfertilized ovule
spore wall ploidy
2n
what does the integument become
seed coat
the seed coat ploidy
2n
the food source is the
megagametophyte
what becomes the new sporophyte
embryo