Gymnosperms: Reproduction, life cycle, uses Video Lecture - NEET

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let us talk about the reproduction in
general so let us see how reproduction
takes place in case of gymnosperms now
the gymnosperms are heteros porous we
some type AK spoke about heterosporous
and hohos polar site hetero means
different scorers and spores so the
sporangia here will produce two type of
spores one is microspores the other is
Magus course so the micro spores are
small in size and they will give rise to
this pores will germinate to form the
male gametophyte and omega spores are
large in size and they will germinate to
give rise to the female gametophyte now
the spores are spirally arranged to form
compact structure called strawberry or
cones now in case of gymnosperms the
strawberry are more commonly known as
cones so we often refer it as male cone
and female cones so that is how the
structure looks like so if you look at
the picture of a pine tree you actually
see a cone-shaped structure so those
cones are noting by the male cones and
the female cones so here we have two
types of spores and we also have two
types of cones so each type of cone will
produce the respective type of spores
for example I mean the microspores will
get spirally arranged to form the
compact structure called the male cone
similarly the mega spores will form the
female cone so microscope microscope
will form the male cone and make up
spores will form the female cone so now
what will happen so something like this
will happen when I talk about the male
strawberry this male strawberry will
have the micro sporangia
and this microsporangia will have the
male strawberry or the male
on with micro sporophyll i stoled you
write what is strawberry it is nothing
but the sporophylls connected together
so here also the male strawberry will
have the micro sporophylls now this will
then produce the micros force so this
will produce micro spores this
microspores will develop into the male
gametophyte and this male gametophyte
will then produce the male gametes or
which is also referred as spunk so this
is how the male gametes are produced
similarly in case of the female
strawberry the female strawberry
contains the mega sporangia t'
megasporangium is consist of the mega
sporophylls these mega sporophylls will
then produce the mega spores which will
germinate to form the female gametophyte
and this female gametophyte will then
produce the female gametes now all
niggas course will not form the female
gametophyte though one of these mega
spores will form the female gametophyte
and then female gametophyte will produce
the female gamete
so now here we see that the male and the
female gametophyte
do not have an independent free living
existence so this male gametophyte and a
female gametophyte which we spoke about
just now so none of them have an
independent existence what do I mean by
three living existence that means they
cannot exist without each other I mean
they are not
independent in their existence they are
dependent so what do I mean by that let
us have a look at that
also the male and female cones can be
present on the same tree or they can be
present on different trees so example of
same tree would be fine so in a pine
tree you can see both the male cone and
the female cones are present whereas in
case of a plant like cycles if a Cypress
plant can either be male or it can be
female so if it is a male plant it will
have the male cones if it is a female
planted it will have the female cones
okay one more thing to be explained here
is that now why did I say that the male
and female gametophyte cannot exist
independently now here this gametophyte
switch I spoke about the always remain
inside the sporangium so they do not
come out of the sporangia and grow and
form an independent organism it will
always remain inside the sporangium that
is why it is said that they do not have
an independent existence okay so now let
us look at the life cycle of a
gymnosperm so this is a gymnosperm
and which is the dominant stage of algae
nose bump so here also sporophyte is the
dominant phase so what happens here this
is my gymnosperm so this is the
sporophyte so it will have the spores
subhead so now if you see the male and
the female sports so from this plant
this plant will have both the male bones
as well as the female pods now here I am
trying to show you the male cones and
Here I am trying to show you the female
cones now inside the male cones you will
have the male sporangium and the male
sporangium will consist of the male
sports so it is suppose this fears are
the male spores and these fears are the
females force which are present inside
the archegonium or the female speranza
so archegonium is a name for the female
sporangium senility and 3d
is the name for the mail sporangium so
now meiosis will happen and these balls
wicked released so the spores which are
released from the male sporangium they
are the micro spores and those released
from the female they are the makers
force so megaspores are larger in size
that the microspores now one of these
mega spores which I have denoted here as
little big so one of these maker spores
will actually form the female
gametophyte so one of these megaspores
form the female gametophyte and these
microspores form the male gametophyte so
now we have both female gametophyte and
nail gametophyte
so these gametophyte will now produce
the gametes so here if you see this is
female gametophyte it produced the
archegonium where the female where the
female gametes are produced now the male
gametophyte will produce the male
gametes and what are the male gametes it
will pass the male gametes to the female
gametophyte what are the male gamete
they are nothing but the pollen grains
so they are passed here and the egg is
already there so now fusion will take
place so first pollination will take
place that is this transfer of pollen
grains to the female gametophyte that
has pollination then fertilization that
is fusion of the pollen grain with the
egg so this fusion will take place so as
a result as I got will be formed now
this is I got will grow gradually to
form the embryo and this embryo will
finally grow back again to form a match
your sporophyte so this is the life
cycle of a gymnosperm so here also the
dominant phase is the sporophyte so now
did you wait a to observe the seed here
what was the role of the seed here
because nouns in moss ponds are the
plants with seeds so here when I was
talking about the embryo what was the
temporal this embryo was actually
present inside this
EGH and then this seed germinates into a
plant so this is a process which all of
us see now today today like you would
have seen you would have yourself
planted so many plants with the help of
seeds so I input the seeds water it
nicely you get a plant so this is what
happening this is what is happening here
so basically your plant when it grows up
when it becomes matured it is nothing
but the sporophyte phase so it will now
contain spores so it will give out the
male spores that is micro spores are
talking about the female spots which are
Vegas pose then they have informed the
gametophyte and a process will keep on
continuing so this is about the life
cycle of a gymnosperm
so here we see that both gametophyte and
next generations new sporophyte develop
on the sporophyte parent plant so if you
see here this is my sporophyte parent
plant this is the parent plant from
where this process started so now when
the gametophyte is formed where ID is
gametophyte spawn the gametophyte are
formed in this plant itself right it is
not formed outside the planet
so both the gametophyte SAR formed on
this plant and that is why it is said
that the gametophyte does not have its
individual existent you do not see a
separate gametophyte like how we saw in
case of a fern or a moss there we saw
the gametophyte was altogether a
different small plant right but in this
case we do not have a separate
gametophyte the gametophyte do not have
their individual existence they have
present inside the parent plant of cells
now again when this seed also germinates
into a new plant so this embryo is also
formed as a part of this plant itself so
now when you take out the so the seeds
when the seeds are also there or when
the phones are also formed they are also
formed in the sporophyte and
for sporophyte itself okay so please
understand these concepts very much
clearly then what happens to the
Gallegos gametophyte and sporophyte
concept needs to be understood very very
clearly please go through the slides
over in the end and then you get until
and unless you get a very clear
understanding the gametophyte and
sporophyte rose in case of bryophytes
pteridophytes and gymnosperm they are
all different and the way it things
happen the way the lifecycle happens
it's nothing different so please try to
and once you understand the lifecycle I
have tried to explain the life cycle in
the easiest possible way you also go
through the life cycle once the life
cycle is clear everything else will
automatically be clear because life
cycle explains at all so with this I
think we have understood the life cycle
of a gymnosperm so here you can look at
this picture this is a pine tree where
you can see a male and a female hole so
these are the cones so both the male and
the female cones are present in the same
plant so the dominant stage here again
is the sporophyte now let us look at the
importance of gymnosperms or does it
have any economic use talking about
economic use one important thing is it
controls soil erosion in forests as I
told you before also that you will see a
lot of gymnosperms in the hitting areas
or in the forest like areas so there it
and there is so much of land there so if
those trees are not there you can
actually imagine vast land just like
that so during heavy rains or flood
there will be lot of soil erosion so it
actually controls the soil erosion some
of its economic uses is it helps in
making of so nail polish perfumes and
also for some food materials it also
acts as remember you would have seen
that as I said these these gymnosperms
have a lot of wood in there because
first of all the trees are quite tall so
you have so much of wood in there so
these days people have actually started
cutting down these trees just to utilize
would twitch is helpfully making
furniture and stuffs like that my daddy
that is also not good because if we end
up cutting down too many trees that will
again cause an imbalance in the
atmosphere because we actually saw how
to plant help it actually controls the
soil erosion it helps to increase the
level of oxygen in that most air so
plants give out oxygen and we need
oxygen to breathe in so if there are
less plants there will be less oxygen in
that post wave so we will get less
oxygen to breathe in so it will be
threatening our survival right so we
should not cut down too many trees so
that the atmosphere remains green and
healthy so these are some of the
economic uses of gymnosperms so with
this thank you
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