Experiment no: 1
Class: IX Biology
Aim: Experiment to demonstrate anaerobic respiration.
Materials required: Mercury, Beakers, Test tubes, Pea seeds.
Principle: Carbon dioxide can be tested by introducing potassium hydroxide into the test
tube, which will float up through the mercury and on coming in contact with gas, will absorb
the carbon dioxide and level of mercury will again rise.
Procedure:
1.
2.
3.
4.
Take eight to ten soaked and peeled off peas.
Push them into the mouth of a test tube filled with mercury.
Invert the test tube filled with mercury in a beaker of mercury.
As a control we will take the same experiment set up with boiled seeds and sterilized
with antiseptic.
Observation:
1.
2.
3.
4.
The seeds will float to the top and will be completely surrounded by mercury.
After two days, the level of mercury in the test tube will fall.
The liberated gas will be found to be carbon dioxide.
In the control experiment, no gas will be liberated.
Inference: The seeds respire carbon dioxide gas.
Precaution:
1. The mercury should be handling carefully as it is dangerous.
Experimental Setup for Anaerobic Respiration
Experiment no: 2
Class: IX Biology
Aim: To prove that carbon dioxide is produced during respiration in germinating seeds.
Materials require: Round bottom flask, Cork, Maize seeds, cotton, lime water,
antiseptic, water, rubber tube.
Principle: free oxygen is used in respiration and there is complete oxidation of glucose
with the formation of carbon dioxide and water as end products. This is clearly
represented by the following reaction:
C6H12O + 6O2
6CO2 + 6H2O + 38ATP
Respiration proceeds only when oxygen is available and is therefore called Aerobic
respiration
Procedure
1. Take two conical flasks and mark as A and B.
2. Place some wet cotton at the bottom of each flask.
3. We took soaked maize seeds in the flask A and same amount of boiled maize seeds in
the flask B.
4. After that, add little antiseptic (carbonic acid) to prevent bacterial growths in dead
seeds, which would otherwise respire and release carbon dioxide.
5. The flask is then should be securely corked and left in similar conditions of light and
temperature.
Observation:
Sl No
Flask A
Flask B
1
The seeds in the flask A are found
germinating.
The seeds in the flask B didn’t show any
sign of germination as they are dead.
Test: Then the gases collected in the each flask are tested.
Sl no
1
2
Test
First we removed the cork of the
flask A and tilted the flask over a
test tube containing lime water and
then shake the test tube. Carbon
dioxide being heavier than air, flow
down in to the test tube.
observation
The gas that was collected in the flask A
turned the lime water milky, showing the
presence of carbon dioxide
Then we removed the cork of the
flask B and tilted the flask over a
test tube containing lime water and
then shake the test tube.
The gas collected in the flask B turned
lime water milky but not to that much
extend like gas collected in flask A
Conclusions: Therefore, we concluded that the germinating seeds give out carbon dioxide.
Precautions: Handle the apparatus carefully.
1. The seed should be boiled nicely so that the germination will not take place.
2. Both of the flasks should be air tight.
An alternative method for the same experiment
Materials required: Conical flask, Capillary tube, Cork, Germinating seeds, Lime water.
Procedures:
1. We took four conical flasks and mark them as A B C and D.
2. We took equal amount of lime water in the conical flask A, B and D.
3. In the conical flask C, we placed germinating seeds.
4. Then we set up the apparatus shown in the figure.
Observation: the air drawn in the conical flask A is cleared of any carbon dioxide present in
it. The clear lime water in flask B confirms that the air entering flask C is carbon dioxide free.
The lime water in flask D turns milky proving that the source of carbon dioxide is only the
germinating seeds.
Improvisation: in this experiment, we improvised suction pump by water running through
rubber tube and that was difficult part for us.
Experiment no: 3
Class: IX Biology
Aim: To show heat is evolved during germination of seeds.
Material require: Conical flask, Seeds (about 200 in numbers), Thermometer, Antiseptic,
Grease, Rubber cork, Spirit lamp, Match box, Tripod stand.
Principle: Geminating (live and respiring) seeds give out heat.
Procedure:
1. A day before we soaked collected dried seeds in water to make it wet so that the
seeds germinate. (24 hours )
2. Next day we collected the required materials for the experiment and proceeded with
our experiment.
3. First we divided the seeds into two equal groups and boiled one group of seeds to kill.
Then the boiled seeds is washed with antiseptic to prevent from bacterial decay.
4. After that we named two conical flask “A” and “B”. To conical flask “A” we put live
seeds and dead seeds to “B”. To each flask we inserted thermometer each with the
cork to make it air tight.
5. After the set up we left it for observation.
Observation:
After 3 days...
Conical flask “A”
Conical flask “B”
Seeds showed germination with increase in
temperature.
There was no sign of germination.
(initial reading 30°C )
(final reading 32° C)
 There was increase in 2° C indicating
heat production during germination.
(initial reading 30°C )
(final reading 28° C)
 There was no rise in temperature rather
decrease in temperature indicating no
germination.
Inference:
1. Germinating seeds produces heat as a result of respiration.
Precaution
1. Make sure that boiled seeds are dead
2. Take care when handling with glass apparatus ( thermometer)
3. Make sure you wash dead seeds with antiseptic to prevent bacterial decay.
Experiment no: 1
Class: X Biology
Aim: To demonstrate diffusion
Material require: beaker, water, crystal KMnO5, spatula.
Principle: Diffusion - the process by which molecules spread from areas of high
concentration, to areas of low concentration. When the molecules are even throughout a
space - it is called equilibrium. Concentration gradient - a difference between concentrations
in a space.
Procedure:
1. Took a beaker and filled it with the water.
2. Slowly placed the crystal potassium permanganate in the beaker containing water, in
one corner.
3. Then observed the changes.
Observation: The crystal KMnO5 slowly dissolved and spread in the water. With passage of
time all crystal KMnO5 dissolved and the molecule of the KMnO5 diffused or distributed
uniformly throughout the water.
Conclusion: we have seen all the KMnO5 crystal was dissolved and molecules of the KMnO5
distributed equally throughout the water making a homogenous solution.
Precaution:
1. Placed the crystals of KMnO5 slowly in the water.
Examples
Experiment no: 2
Class: X Biology
Aim: To show that chlorophyll is necessary for photosynthesis.
Material require: De-starch leave, Alcohol/ Sprit, Sprit lamp, Iodine solution, Match box,
Beaker, Testube, water, Tripod stand.
Principle: Chlorophyll is the molecule that absorbs sunlight and uses its energy to synthesis
carbohydrates from CO2 and water. This process is known as photosynthesis and is the basis
for sustaining the life processes of all plants.
Procedure:
1.
2.
3.
4.
5.
6.
De-starched the leaves by keeping the plant in a dark room for a few days.
Placed the plant in the sun.
After 1hour, plucked one leaf.
Made its outline on paper and marked on the outline, the green and non-green areas.
Dipped the leaf in boiling water for a minute to kill the cells.
Boiled the leaf in methylated spirit over water bath till it became pale-white due to
removal chlorophyll.
7. Placed it again in hot water to soften the leaf.
8. Spread the leaf in a Petri-dish and pour iodine solution in it.
Observation:
1. Only green parts of the leaf turned bluish showing the presence of starch.
Inference: chlorophyll is necessary for photosynthesis.
Precaution:
1. Carefully handle the apparatus.
2. Don’t use excess methylated spirit while boiling leaf over the water bath.
3. Gently spread the leaf in the Petri-dish as it is fragile.
Experiment no: 3
Class X biology
Aim: to demonstrate a conditioned reflex (Pavlov’s experiment on dog).
Material require: dog, food, bell
Principle: In a now classic experiment, Pavlov first performed a minor operation on a dog to
relocate its salivary duct to the outside of its cheek, so that drops of saliva could be more
easily measured.
Periodically, a bell was rang, followed shortly thereafter by meat being placed in the hungry
dog's mouth. Normally, meat causes a hungry dog to salivate, whereas rings have little effect.
The dog's salivation to meat is an unconditioned reflex - it is in-born, in that dogs do not have
to learn to salivate when food is placed in their mouths. Initially, the dog shows little
responsiveness to the bell rings. Over time, however, the dog comes to salivate at the
sounding of the bell rings alone. When this occurs, Pavlovian conditioning or classical
conditioning has occurred, in that a new, or conditioned, reflex has developed. This
confirmed Pavlov theory that the dog had associated the bell ringing with the food.
Observation:
Inference: Here the condition or stimulus is the sound (not the sight of the food) and the reflex
is salivation.
Experiment no: 4
Class: X Biology
Aim: to show that roots absorbs water.
Materials require: Test-tube, Young Leafy shoot with intact root, mustered oil, test-tube
stand
Principle: Roots absorbs water and supports the entire plant
Procedure:
1. We collected the required materials for the experiment
2. We named two test-tube “P” and “Q” and then filled test-tube “Q” with water and
marked the level. To test-tube “p” we inserted leafy shoots with intact roots with same
level of water.
3. After that we put few drops of mustered oil in both test-tube to prevent loss of water
by evaporation.
Experimental set up
Observation:
Next day...
Test-tube “P”
There was drastic fall in level of water
indicating that roots absorb water which
helps the entire plant.
Test-tube “Q”
There was little fall in level of water
indicating there wasn’t absorption of water
in absence of root.
Inference: Roots of the plant absorbs water and helps the entire plant.
Precaution:
1.
2.
3.
4.
carefully handle the glass apparatus
make sure that plant taken for the experiment has intact roots
Level of water in the test-tube should be same
Put the oil above water to prevent evaporation of water
Experiment no: 5
Class Biology
Aim: An experiment to demonstrate transpiration in green plants.
Material s required: Bell jar, potted plant, wooden stick, Cobalt chloride paper
Principle: transpiration is loss of water as water vapour from the aerial parts of the plant.
Cobalt chloride paper is an indicator of moisture. It is blue when dry, pink when exposed to
moisture.
Procedures:
Step A
1. We took well watered potted plant with leaves.
2. Enclosed the pot completely within a polythene bag and tied the mouth of the bag
firmly around the base of the stem.
3. It was done to prevent the escape of water vapor.
4. Covered the entire plant under the bell jar.
Step B
1. Arranged another similar plant.
2. Covered it with a bell jar exactly in the same as the first one, except we had also kept
a piece of dry cobalt chloride paper by the side of the plant inside the bell jar.
3. The paper was pasted to a wooden stick.
Step C
1. We took third bell jar without plant but with cobalt chloride paper.
2. We kept all the bell jars together in the sun.
Observation:
1) After a day we observed:
- The first bell jar (A) showed water droplets condensing on its inner walls.
- The second bell jar (B) showed a similar condensation of water droplets but
initially blue cobalt chloride paper remained same.
- The blue color of the cobalt paper in the third bell jar (C) did not change and
there was no water droplets condensed on walls.
Inference
1. The third bell jar (C) proves that there is no moisture in the air.
2. Actually condensation of water droplets and change of color in cobalt chloride
paper form blue to pink proves of transpiration in green plants BUT
3. The experiment failed because cobalt chloride paper did not work.
Precaution:
1. All bell jars should be made air tight by applying grease; otherwise air from outside
will get inside.
2) All potted plants should be covered by polythene bag and make sure the water vapour
from pots do not escape.
3) Cobalt chloride paper should be tested before using it in the experiment.
An experiment to demonstrate transpiration in plant
Thank you
Tashi Tenzin
Ugyen Thinley
Thinley Penjor
Dawa Tshering