Hello Students
Our today's biology experiment is one of the
important
If this process wasn't in existence then the
life on earth was impossible.
Do you know which process are we am talking
about?
Yes Ma'am eating food.
Right Mohsin, However I'm talking about food of plants and not ours.
That how plants create their food using sugars and carbohydrates. And we call this process Photosynthesis.
Let's see what is in this process.
Photosynthesis is a process where green plants take carbon-dioxide and water from environment
and make their food in form of carbohydrates or sugar.
For this process plants needs energy which
they get from sunlight and chlorophyll pigment
is which present in their leaves.
During this process they release oxygen and the chloroplast present in the leaves absorbs
energy by light so that they can store excess
energy in the form of ATP (Adenosine Triphosphate).
Interesting Ma'am. Yesterday I was reading
that Chloroplast is called as Photo-receptors
and due presence of chlorophyll pigment it's
green.
That's right Qirat. Actually Chloroplast has
different membranes.
And the reactions occurring by light happen in the internal and external
membrane of thylakoid membrane instead of Stroma.
Ma'am is it correct that photosynthesis in
all the green plants happens at the same speed?
And what if one plant has more chlorophyll
than other than what would happen?
Good question Imran. Actually plants having
more amount of chlorophyll will have more
speed of the process of photosynthesis, because
due to this more energy can be stored.
Photosynthesis process speed also depends on carbon-dioxide,
sunlight and temperature.
Water and carbon-dioxide are raw materials,
Hence without them the process of photosynthesis can't happen
and if oxygen production is more
speedily than it represents that this process is happening fast.
Ma'am let's start the experiment otherwise
Imran would keep on asking questions.
What weird plant is this? Mohsin their isn't
any issue in asking questions still let's
start our experiment.
This plant is called Hydrilla and this is
an aquatic plant that's why it grows in water.
We'll use this plant in our experiment because
it uses very less sunlight
that's why we can use it in our laboratory experiment.
Do you know this plant only needs 1% of sunlight
and it can grow in any sort of water like
in lakes, water tanks and ocean and only needs
few inch depth of water.
That's right Qirat. Now we'll start our experiment.
And first of all let's see what all equipments are needed.
We'll use one
1000ml beaker
1 Small beaker
Match sticks
And Stirrer
And a Glass funnel
Sodium Bi-carbonate
Spatula (Used in measuring quantity of substances)
Test-tube
And Obviously a Hydrilla plant.
Ma'am How will we use all these things in
showing the process of photosynthesis? And
why this match-stickers are we going ignite
fire here?
No Imran, we won't lighting the fire however
when we'll start the experiment then you'll
understand why are using match-sticks.
Let's start setting up the equipments as for
the photosynthesis process we'll have to keep
them in sunlight for 2-3 hours.
Now we'll do the experiment by ourself and
Mohsin you'll help me in this experiment.
First we'll fill the 1000ml beaker with sufficient
water so that the stem of glass funnel is
fully dipped in water.
Then we'll add 1 tea spoon sodium bi-carbonate
using spatula and mix with the stirrer.
Ma'am why have we added sodium bi-carbonate
in water?
Imran we are using sodium bi-carbonate in
water so that it can generate carbon dioxide.
And you know carbon dioxide is important for
photosynthesis.
Ma'am this looks like baking soda, which my
mother uses to make cakes. Yesterday she made
chocolate cake for me and it was yummy.
Mohsin sodium bi-carbonate is also called
as baking soda and
it's chemical formula is NaHCO₃
Exactly. Let's add the other things to this.
Take couple of branches of fresh Hydrilla
plant and make bunch of them
like this
can you see this
and now adjust them in glass funnel in such a way that it can
fit in glass funnel stem
Ok
Now we'll carefully place the funnel in 1000ml beaker which already filled by water
and place very carefully in such a manner that the stem in completely under water.
Keep in mind that the water is not too cold
otherwise the process of photosynthesis will slow down.
Next we'll take the test tube and using small
beaker we'll fill water in it in such a manner that there are no air bubbles in it.
Fill till the top
Wait for some time so that there should not be any air bubbles
After that hold the test tube closing the top using
thumb so that no air can enter the tube.
And then we'll place it upside down on
the glass funnel as shown.
And we'll have to do it very carefully that should be no
air in it.
First we'll dip in water like this
And lift off your thumb and see it has no air bubbles
And in the same way keep it on glass funnel stem
And we have to make sure that the air can't enter the tube.
Ma'am Please tell why this process is so important.
Because we want to accumulate oxygen using
photosynthesis process, if there will be air in test tube
then how we'll able to understand
whether the Hydrilla plant is releasing oxygen or not.
Now we'll take this equipment in sunlight,
Mohsin you will help me in this too and make
sure that this equipment is in
bright sunlight.
Hydrilla plant will get some sunlight and
I'll get some exercise.
Good
After keeping the equipment in sunlight for
couple of hours Mohsin is bringing it back.
Let's see the situation now.
Ma'am I can see the air bubbles releasing
air bubbles seems like it is breathing.
Correct
You can see small air bubbles getting released
and getting gathered in the test tube.
We can see the air bubbles in test tube.
We can see the gas bubbles, however, we'll have to test it whether it is oxygen or not.
And the easiest way to test is we'll take
the burning match stick inside the test tube.
If there will be oxygen match stick will catch
fire the flame will increase because oxygen helps in compulsion.
Perfectly right Qirat.
Now to test the oxygen the match stick process as she has mentioned.
For this
Now see we'll take out the test tube very carefully from
beaker
and release entire water in beaker
and immediately close the test tube by the help of our thumb very
carefully.
Now we'll check whether this has oxygen or
not.
Imran now ignite the match stick and make
sure it does blow out and bring it close to the test tube.
Wow Ma'am due to oxygen the flame of the match
stick has increased.
And we could have made more oxygen if the
Hydrilla plant was big and provided the more carbon dioxide and sunlight.
. All these factors effect the process of photosynthesis.
Exactly
By this experiment we can conclude
1. For the photosynthesis sunlight is very
important.
2. And there were no air bubbles before keeping
the equipment in sunlight.
3. Increased flame of match stick proved that the gas gathered in the test tube was oxygen.
Now let's quickly recall the experiment quickly.
In today's experiment by the help of aquatic plant Hydrilla
A) How by the process of photosynthesis plants
prepare their food.
B) We kept the Hydrilla plant in glass funnel
in submerged in beaker full of water.
And placed water filled test tube on the stem
of glass funnel upside.
C) After keeping this equipment in bright
sunlight for 2-3 hours we saw the there was
oxygen released from Hydrilla plant and accumulated
in the test tube.
D) We took off the test tube and brought the
burning match stick near the test tube due
to which it's flame increased which proved
the presence of oxygen
Alright students Thank you very much for doing
this experiment with me. We shall meet again
with new experiment.
Till then Good Bye. Thank you Ma'am
