Experiments from class IX Biology text book.

Aim of the experiment: To prove that carbon dioxide is

produced during respiration in

germinating seeds. Materials required:

Round bottom flask. Cork. Maize seeds Wet cotton. Lime water.

Principles ;

Procedures ;

a. Take two conical flasks and mark as A and B.

b. Place some wet cotton at the bottom of each flask.

c. We took soaked maize seeds in the flask A and same amount of boiled maize seeds in the flask B.

d. After that, add little antiseptic(carbonic acid) to prevent bacterial growths in dead seeds, which would other wise respire and release carbon dioxide.

e. The flask are then should be securely corked and left in similar conditions of light and temperature.

Observations

Sl # 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 #

Test Observations

1 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.

The gas that was collected in the flask A turned the lime water milky, showing the presence of carbon dioxide.

2 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, the conclusion is that

the germinating seeds give out

carbon dioxide. Precautions: Handle the apparatus

carefully. : the seed should be boiled

nicely so that the germination will not take place.

: both of the flask should be air tight.

An alternative method for the same experiment.

Materials required: Conical flask Capillary tube Cork Germinating seeds Lime water.

Procedures:a. We took four conical flask and mark them

as A B C and D.b. We took equal amount of lime water in

the conical flask A, B and D.c. In the conical flask C, we placed

germinating seeds.d. Then we set up the apparatus shown in

the figure.

Explanation: 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.

Experiments from class X Biology text book.

Aim of the experiment: to demonstrate a conditioned reflex.( Pavlov's experiment on dog.)

Explanations: He noted that under normal conditions, no animals will secrete saliva in response to the ringing of bell or to any other sound. But when the bell was repeatedly sounded simultaneously with the presentation of food during an adequate period of training, the dog salivated at the sound of the bell even when there was no food at that time.

Here the condition or stimulus is the sound(not the sight of the food) and the reflex is salivation.