hello guys welcome you are watching the
official channel of conventional
education the previous video we had
learnt about the life processes plant
nutrition and activities based on it now
in this video we'll be learning
insanely about the total structure of
the leaf and mechanism of photosynthesis
so without delay let's get into the
video here's the diagram of the
structure of a leaf the top of the
diagram you guys can see an protective
layer it is known as cuticle which helps
in covering the epidermis cells of the
leaf and the upper layer of the cuticle
is waxy and waterproof which helps to
reduce the loss of water from the leaf
now coming to the second one upper
epidermis the upper epidermis is a
single layer of cells containing a few
or no chloroplasts in it the cells in
upper epidermis are quite transparent
which helps them to pass the light that
strike the leaf to the underlying cells
it means that when the light strikes the
upper epidermis as the upper epidermis
is quite transparent it can just pass
the light through it to the underlying
cells easily. Now coming to the third one
palisade parenchyma the cells of
palisade are elongated tube next
structure the chloroplasts in this cell
absorb a major portion of light energy
used by the leaf. Now the fourth one
xylem I think you guys are familiar with
xylem and phloem xylem means transport
of water within the plant body then
fifth one phloem phloem means transport
of food materials within the plant body
now the sixth one bundle sheath here it's
not mentioned but I will explain you
bundle sheath means the covering portion
of xylem and phloem is known as bundle
sheath that is a protective layer of
xylem and
phloem Now coming to the seventh one
spongy parenchyma
it has irregular shape cells with few
chloroplast in it and large 
intracellular spaces in this cell
exchange of gases takes place like
carbon dioxide is a lot in and oxygen is
diffused out then the eighth one air space
or sub stomal cavity it it is the
pathway of exchange of gases like carbon
dioxide and oxygen passed through this
path now the ninth one lower epidermis
this epidermis contains stomata and Gaurd
cells in a it contains more stomata
about thousands per square centimetre
when compared to upper epidermis now the
10th one the last one Stomata
it is an opening in the epidermis which
allows in transpiration transpiration is
nothing but exchange of gases now let's
study the structure of chloroplast you
guys need not to panic I'll let's explain you
in an easy manner chloroplast has an
inner and outer membrane inside the
chloroplast there are stacks of
membrane-bound compartments these are
known as thylakoids
and in this thylakoid there is thylakoid
membrane and in this thylakoid membrane
there is lumen again in this lumen
there is water remember these steps in
thylakoid there is a local membrane and
in thylakoid membrane there is lumen and
Lumen consists of water now the group
of thylakoids that means number of
thylakoids are known as Grana the fluid
present around ah that means the fluid
present inside the chloroplast is known
as stroma that's it this is the
structure of chloroplasts now let's look
into the mechanism
of photosynthesis in chloroplast
there are two types of mechanisms light
reaction and dark reaction light reaction is
known as photolysis hill's reaction
light dependent reaction and a second
one dark reaction dark reaction is known
as biosynthesis Calvin's reaction light
independent reaction as now let's look
into the introduction of light reaction
first let us know the main theme of
photosynthesis the main theme of
photosynthesis is to capture or convert
the light energy to chemical energy then
the water molecule is splitted and
conversion of carbon dioxide to
carbohydrates why it is named as light
reaction and light dependent reaction it
means that this reaction only occurs in
presence of sunlight now let's look some
deeper about the light reaction in light
reaction the chlorophyll molecule
absorb the light energy from sunlight
in the form of photons these photons
splits the water molecules which is
present in lumen and turns to turns
water that means h2o to hydrogen ions
and hydroxide as we studied in the
structure of chloroplast
we studied that lumen contains water so
here the water contained in lumen is
splitted to hydrogen ions and hydroxide
by the action of photons as you can see
the equation over here it's h2o by the
action of photons splitter to H+ ions
and OH minus ions splitting off
water molecule into hydrogen and
hydroxide by the action of photons is
called photolysis the entire
process of light reaction is observed by
the scientist Robert Hill so it is also
named as
Hill's reaction and photolysis the light
reaction occurs in Grana
then what happens to the hydrogen and
hydroxide ions the hydrogen  ion
formed in the Granum is gone into the
stroma fluid the hydroxide ion again
reacts with water and form oxygen ATP
and NADPH ATP means adenosine
triphosphate and NADPH means
nicotinamide adenine dinucleotide
phosphate now let's get to the  dark
reaction here's the dark reaction dark
reaction is also known as biosynthesis
Calvin's reaction light independent
reaction and carbon fixing reaction
first let us know why it is known as
dark reaction and light independent
reaction it means the reaction doesn't
require or utilize the sunlight so it is
known as dark reaction and light
independent reaction if it if it doesn't
require the sunlight then it means that
it doesn't require it doesn't occur in
the nighttime no it occurs in both
daytime and the nighttime so now why it
is known as bio synthesis reaction in
this reaction the glucose molecule is
formed so it is known as bio synthesis
reaction and why it is known as carbon
fixing reaction it is known as carbon
fixing reaction because the carbon
dioxide and water molecule is converted
to sugar molecules so it is known as
carbon fixing fixing reaction and why it
is known as Calvin reaction it is known
as Calvin reaction because the
scientists Calvin has first observed
this reaction so it is known as Calvin
reaction the dark reaction occurs in the
stroma of the chloroplast where they
utilize the products of the light reactiom
what are the products of the light
reaction a ATP and nadph are the
products of light reaction
these products are utilized in the dark
reaction plants capture the carbon
dioxide from the atmosphere through the
stomata and proceed the Calvin cycle
what is calvin cycle the calvin cycle is
a cycle of chemical reactions performed
by the plants to fix carbon from carbon
dioxide into carbon sugars that means
the fixing of carbon dioxide to carbon
sugars is known as skin in cycle the
calvin cycle the ATP and nadph form
during light reaction drives a reaction
and convert 6 molecules of carbon
dioxide into one sugar molecule i.e  glucose
so here in this reaction glucose is
formed and the products of calvin cycle
are adp and nadp+
ADP means  Adenosine diphosphate and
NADP plus means nicotinamide adenine
dinucleotide phosphate plus now let's
see the diagram of both light reaction
and the dark reaction here you can see
the light passes through the thylakoid
and in the thylakoid lumen is present
In the lumen  the h2o is present it reacts
and forms oxygen and ATP and nadph this
ATP and NADPH reacts with co2 and
utilized and forms the sugar ch2o and
glucose again it gives the products ADP
adp and NADP plus these all are
occurred by the action of photons so
this is the process of light reaction
and dark reaction now let's see how do
organ in organisms like amoeba obtain
their
nutrition the organisms like amoeba
extend their body to obtain the
nutrition like you can see in the
picture
here's amoeba and here's the food
particle the amoeba extends it its
pseudopodia to go near to the food
particle after it extends
thoroughly it just covers the food
particles with its food vacuole now the
food particle is inside the food vacuole
then slowly the amoeba covers the food
particle with the with its body thank
you for watching this video
catch you guys in the next video bye bye
