Reproduction 2, gymnosperms cone structure and reproductive cycle Flashcards
whats a disadvantage of homospory
new sporophyte, while developing from the zygote, is temporarily dependent
on a tiny gametophyte for its start in life.
advantage of having a sporophyte
embryo uses resources and protection
Megagametophyte is retained inside the
maternal sporophyte; an ovule
Oldest known seeds lived
350 million years ago
First seed plants
were gymnosperms, but fernlike
An early seed plant resembling
a fern
Medullosa
In most conifers, where are seeds contained
seeds are in cones
and are naked–> not contained in fruit
how many cone types do MOST conifers have
2
pollen cone and seed cone
Where do seeds develop on pine seed cones
seeds develop on
woody scales
-Pollen cone where are microspores produced
-what do the microspores develop into
microsporangia
microgametophytes
Pines produce vast quantities of pollen in the
spring
in pine seed cones, Each scale bears
2 ovules
parts of ovule
microphyle
integuement
Megasporangium in ovary
Nucellus
urethra in ovary
microphyle
outer layer of ovary
haploid or diploid?
integuement
diploid
layer containing egg in ovary
archegonium
Egg
haploid or diploid
haploid
female gametophyte haploid or diploid
haploid
the nutritious tissue is the
female gametophyte
what do some conifers require to release their seeds
fire–> forest fires
Conifer reproduction after fertilization
haploid or diploid
- zygote develops into the embryo of a seed
- wings develop
- young sporophyte (seedling)
- sporophyte–> tree
- develops male and female cones micro and macro sporangium
- megasporocyte and microsporocyte that are contained within cones undergo meiosis
diploid
Conifer reproduction after meiosis, megaspores
haploid or diploid
1.contained in the megasporangium, 3 megaspores degenerate.
2. one megaspore develops into female gametophyte
3. contained in archegonium
haploid
Conifer reproduction after meiosis, microspores
haploid or diploid
1.microspores released(pollen)
2. generative cell divides producing 2 more cells(pollen tube and sprematogenous cell? idk)
3. spermatogenous cell divides producing 2 sperms
4.pollen tube grows towards archegonium, and unites with egg.
5.Zygote(2n) formed in archegonium
haploid
fleshy seedy cones
juniper berries
fleshy seed coat
aril
red fleshy aril
yew
seeds enclosed in fleshy seed coat with nauseating colour
Ginkgo biloba
