L7 : Biological Magnification - Our Environment, Science, Class 10 Video Lecture

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and what is the other conclusion from
this discussion that is going to
biological magnification so you might be
wondering what is this new term now so
let us see what it is it is nothing but
progressive accumulation of chemicals at
each trophic level so here we saw that
since the food which any of the living
organisms existing on this earth eat is
some is in some or the other way related
to one another right whatever we eat
either comes directly from plants or
from any of the animals which directly
or indirectly feed on plants let so
things are related so our food are all
related now in these food sometimes
harmful chemicals and also in turn
harmful poisonous things can also enter
the food chain so now the question is
how can these things enter for example
let me give you an example it is suppose
there are many pesticides and
insecticides which we use in the fields
for improvement in crop yield right now
these chemicals where do they go they
remain in the soil or they these
chemicals get washed away with water so
they remain either in water or in soy so
from that soil they can very easily
enter into the plants now once they
entered the plant something which has
entered plants have actually entered the
food chain because plants are the
producers so all living organisms depend
on plants directly or indirectly so
something which has entered into plants
means it has entered into the food chain
now it is seen that these harmful
chemicals if it enters into the food
chain when it passes from one organism
to another as it goes higher in the
trophic levels the amount of chemicals
or the concentration of chemical keep
increasing like we have seen that as the
tropic levels increases the amount of
energy transferred
Greece's so in a similar fashion here in
this case the amount of harmful
chemicals keep increasing
why because chemicals are something
which are not degradable that means
there is nothing that can break down
chemicals into simpler form which can be
absorbed by an organism right
so it remains unabsorbed and that is why
it keeps the actual ating so the higher
the trophic level the greater is the
concentration of chemicals even though
the amount of energy flow decreases but
the concentration of chemicals increases
let us look at an example you would have
seen that in the soil as I said in the
soil you will find many harmful
pesticides insecticides or chemicals you
would have heard of DDT Hey so this DDT
is a chemical which is gently found in
the swine because this is also used for
the purpose of crop improvement and
increase in soil fertility and all those
stuff so now suppose if this this is the
soil and you have DDT present here now
here you see in the soil you generally
see earthworms earthworms are very
common in soil
so here also you can see this artwork so
now this earthworm feed so on this swipe
so what happens that DDT enters into the
earth one now let us suppose that the
concentration of DDT in the soil was
very less it was not that too much heavy
amounts of DDT was present it was may be
very less amount of DDT was present say
for example the amount of DDT present in
the soil was 10 ppm what is ppm it is
particle per million that means for 1
million particles of soil only one
particle of DDT only 10 particles of DDT
was present that is called particle per
medium so that means 10 particles of DDT
was present in 1 million particles of
soil so it is a very low concentration
now when this soil is fed upon by the
art one what happens it was seen that
the concentration of DDT inside the art
one was around 85 ppm so it increased
now the question is how because deedie
is something
which doesn't get degraded then it
cannot be decomposed into simpler forms
which can be absorbed by the earth one
so it is it doesn't get broken down into
simpler forms so it will remain as it is
now when the earth one feeds on the soil
it will feed good quantity of soil and
that good quantity of soil will have a
lot of DDT so the concentration of DDT
inside the body of the art worm will
increase now this earthworm in turn will
be eaten by some burden so when this
body heats up this earthworm it is seen
that the concentration of DDT inside the
body of this bird reaches to around to
50 ppm because this bird is not going to
eat just one art one because I told you
the concentration as 85 ppm in one art
form but the bird is going to eat maybe
some 10 or 20 art ones so it is going to
eat many heartworms therefore the
concentration of DDT is going to
multiply inside the body of the bird now
when we start it so here what is my food
chain so if you look at the food chain
here in the soil it was very less then
it was the earthworm and then it was the
bird and the concentration oil here was
10 which was which is considered to be
very less and which is not lethal it
will it will not kill a person but when
it then it reached 85 even that was okay
but when it reach truth 50 it became
lethal for the bird in the bird legs so
that means if you have a food chain with
too many trophic levels then there are
two add one these advantages one is that
if by chance any harmful chemicals or
acid enters the food chain its effects
will be worse at the higher levels so if
you have more number of levels the
effect is going to be worst at the
higher levels and the second
disadvantage is that as the number of
levels increases as you go higher in the
trophic level the amount of energy that
is actually getting transferred to that
level becomes very less so there is very
less energy available for the higher
levels so because of such
reasons we generally see food chains
consisting of three to four level
scrolling now in a similar fashion we
also observe so this phenomenon is known
as biological magnification Magnifico
Magnifico in the word magnify means to
amplify to increase so that is why this
is defined as progressive accumulation
of chemicals at each trophic level that
means with each trophic level the
accumulation increases that is why it is
a progressive accumulation so we also
see biological magnification in the
grains pulses vegetables which we eat so
which which are good things we eat these
days for everything they will put
insecticides right so it you have
generally seen that your parents would
advise you to wash fruits before you eat
wash vegetables before you cook them so
why do we want things to be washed why
do we want these vegetables to be boiled
and cooked properly so that we can get
rid of the maximum amount of the
undesirable things which are present in
those objects however these means also
can't remove them completely sometimes
they still have some amount of pesticide
or some amount of undesirable substances
so we consume food just like that so now
the concentration of those harmful
substances as we consume them like for
example grains when I talk about veins
or pulses when you prepare pulse is it
just one grain of a pulse will you
prepare or you consume no right you just
take one bowl full of the pulses so you
have so many pulses there right so when
their food actually goes inside our body
the concentration of those pesticides or
those harmful chemicals also increase
that is why it is always advisable to
wash boil and cook things properly
before we eat so this was all about
biological magnification I think with
this I have completed my discussion on
food chains so what can we cover so far
we spoke we have talked about eCos
we have talked about the biotech
components of ecosystem and the
non-biological and the abiotic
components we have further talked about
the biotic components wearing we talked
about the different types of biotic
components producers consumers and
decomposers and the food chain thank you
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