Questions - Evolution Video Lecture - NEET

hello friends this video on evolution
part 19 is brought to you by exam feel
calm no more fear from exam so now we
have reached towards the end of this
lesson and let us look at some of the
questions to see if you have got the
lesson right question number one it's
clean antibiotic resistance
observed in bacteria in light of
Darwinian selection theory now what did
we learn in Darwinian theory so in
diving in theory we saw that nature
always selects the fittest and nature
always support the fittest so whichever
trade groups of survival advantage
nature supports that so that was the
basic information given by the Darwinian
theory now what happens when bacteria is
grown in a medium with antibiotics let's
see so when bacteria was grown in
antibiotic it was seen that most of them
died because they cannot grow in a
medium with antibiotics amplified in
kills bacteria so that is really on time
but there were very few of them which
were resistant to the antibiotic and
while there they resistant that was just
a matter of chance which would have
happened due to mutation due to some
change in the genetic makeup so they
were resistant to the antibiotic and
that is why they survived
now these small number of bacteria which
survive this resistance gave a survival
advantage to bacterium so it could help
the bacterium to survive better in
adverse conditions so that means I knew
it
this trait had a survival advantage and
that is why as for natural selection
this trait would be supported by nature
so as a result on further reproduction
there are chances that more and more
resistance bacteria will be produced so
as a result antibiotic resistance will
be observed in bacteria because more and
more resistant bacteria and
due to natural selection so as I said in
that minion theory we saw that nature
selects the fittest so the fittest here
in these terms would be the one which
are resistant to antibiotic and
therefore they can grow better and it
has imitates the inferior ones inferior
ones are the ones which died so they are
all born so only the resistive one will
remain and that is why one further
reproduction they will produce the
resistant variety of bacteria so nature
supports only the advantageous genetic
mutations
therefore resistant bacteria will
multiply and their population will
gradually increase question number two
attempt giving a clear definition of the
term species so when we talk about
species it is always a group of
organisms that can reproduce amongst
themselves so this is the most important
criteria to call a group of organism as
species if they can introduce up they
can interbreed amongst themselves
that means they belong to the same
species however two organisms of
different species cannot interpret so if
you remember that I have been skin just
you saw the finches which came at the
beginning to the island they all belong
to the same species therefore they could
reproduce amongst themselves even though
they have short opaque and raga beat
they could reproduce among themselves
but later when Scott's own limitations
happened then what happened
a lot of different finches we're reduced
and all these finches were not belonging
to the same species so they could not
interfere with each other
so they all belong to different species
so eigen isms belonging to two different
species do not interview so they cannot
make amongst themselves question number
three try to trace the various
components of human evolution for
example brain size and function skeletal
structure dietary preference etcetera so
how all these things changed in
different stages of human evolution so
let us look at the important components
so one of the important components would
the brain capacity because brain is one
of the very important part of human
beings which is not present in all other
animals so it all the story started with
we started with drive to think this so
in DRI of the thickest and dramatic
thinkers it was even less than 400 CT CC
with Australian thickness it increase to
450 then with Homo habilis it increased
to around 700 Homo erectus it went up to
800 to 1100 and finally Homo sapiens
have 1200 to 1600 CC so if you compare
it with dry up Whitaker's it has
improved a lot and that is why the brain
has gradually developed so this is how
it increased with time and with
evolution the next thing which we'll
talk about is the food habit so
initially they ate only fruits or seeds
but gradually with time they started
eating different types of stuffs
initially it was only fruits then seeds
and nerves then herbivorous that is they
ate grass roots and plants and all those
kind of vegetables then nature they
became only kind of orders that is they
could eat only flesh but when Homo
erectus come into picture from there on
they became omnivorous metals they could
eat grass and clients at the same time
they could eat meat as well the third
thing we'll discuss is the posture as I
said initially they were not erect the
more human they became they became
smooth the moon Dilek today we can see
here in this picture you can may 3 as
you see here it is completely bent and
it was almost in ik here also his erect
but slightly bent here it is completely
hidden and here also it is completely in
this portion using it was slightly bent
before but later in Homo sapiens this
was also getting so it was completely
getting so the question was initially
ape-like then semi erect and then
finally healing but however it was it
since Australopithecus they were all
erect but then I changed initially the
hiatus on
one meters then it was 1.5 meters then
1.5 to 1.8 meters so the height also
gradually increased over time so this is
how the evolution took place and as I
said evolution is a continuous process
so evolution is happening even now so
even now in human beings there are some
small small changes which are not
getting noticed but those changes are
taking place so maybe over a period of
another thousand years or so some
changes would have already taken place
question number four can we call human
evolution as adaptive litigation so
first and try to remember what is
adaptive radiation so adaptive radiation
is a process where from one species it
revolution happens and it gives rise to
multiple species so probably you start
with one disease and you end up having
many species but in human evolution that
doesn't happen human beings are always
they all belong to homo sapien so they
all belong to the same species so it is
not that you ended up having multiple
species of human beings all the human
beings whether they are short they are
tall their fact they are thin they are
dark they're fair they all belong to the
same species in that has homo sapiens
and they can all interbreed they can all
have reproduce amongst themselves so
they belong to the same species so it is
not at all an example of adaptive
radiation because an active regulation
refers to a pollution of different
species with time and in this case
different species do not evolve so if
you talk about adaptive radiation the
darwin's finches are the good examples
where you see that only one species of
Finch enter the island and then litter
it give rise to around 13 to 15 species
of the finches
so this is an example of adaptive
radiation then you mind us then what
kind of evolution happens with human
beings human evolution is rather an
example of energy in essence so what
does the meaning of imagine
like how your biogenesis that means
formation of life
Eugene essence is always about formation
and what is Ana all about it is about
rapid evolution in ancestral form
without giving rights to new species so
in imaginations what happens is that
from the ancestors changes keep
happening and the entire structure and
form everything keeps on changing but it
doesn't give rise to a new species the
species remain the same it is just that
it keeps on changing and gradually the
ancestral form vanishes off the
ancestral form becomes extinct and new
form exists so that is how that is why
you would have seen that right now Homo
sapiens exists so all the human beings
that exist on the earth they all belong
to Homo sapiens so even the previous
generation the generation which was
there before Homo sapiens like the
Neanderthals or the Homo habilis the
Homo erectus all of them have gone so at
one particular period of time only one
particular stage would exist in case of
Ana Genesis so you will not have by the
Homo habilis and the Homo sapiens all
existing together so gradually as new
forms will be formed the older form will
keep on vanishing vanishing in the sense
they will keep on dying so the ones
those qualms dying so the new form which
is being formed they will carry forward
the changes to the next generation and
that is how this process will take place
so no new species will be formed it will
always belong to the same species but
there will always be some rapid changes
happening in the ancestral form so with
this we have reached towards the end of
this lesson and I hope that this lesson
on evolution would have helped you and
you would have actually gained knowledge
about how evil you should happen and why
evolution happens so with this
let's end this lesson and see you all in
the next lesson thank you
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