1
Question
Describe one experiment each you would perform to demonstrate the following
phenomena:
The germinating seeds
(a) Produce heat,
(b) Give out carbon dioxide,
(c) Can respire even in total absence of air.
phenomena:
The germinating seeds
(a) Produce heat,
(b) Give out carbon dioxide,
(c) Can respire even in total absence of air.
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Solution
Following phenomena describes the experiments:
(a) Aim: Experiment demonstrating the fact that germinating seeds produce heat.
Procedure:
- Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
- Approximately 200 pea seeds or beans would be used in the experiment. Soak them in water for more than 24 hours.
- Split the seeds into two equal groups approximately.
- One group of seeds are killed by boiling them and washing them with dilute formalin in order to restrict bacterial decay.
- The live germinating seeds need to be placed in flask A and the boiled/killed seeds in flask B.
- Introduce a thermometer into each of the flasks and seal their mouths with cotton wool.
- Take note of the initial reading observed in the thermometer.
Inference:
- A few hours later, thermometer in the flask A shows a higher reading depicting that the seeds that germinate generate heat.
- Flask B shows no rise in the temperature.
(b) Aim: Experiment demonstrating the fact that germinating seeds produce carbon dioxide.
Procedure:
- Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
- At the base of both the flasks, place wet cotton wool.
- In flask A, take a few soaked seeds of pea, simultaneously take equal quantity of boiled seeds in flask B.
- To flask B, add some carbolic acid so as to inhibit bacterial growth on the dead seeds.
- Seal the flasks with a cork, leave them undisturbed for a couple of days.
- Observe the changes.
Inference:
- Post few days, germination of seeds in flask A is observed.
- Flask B shows no signs of seed germination.
- Cork is removed to test the gases in each of the flasks. The flask is toppled over a test tube which carries limewater. The test tube is then shaken up.
- Indication of carbon dioxide as expected in flask A is observed when lime water turns milky, thereby depicting that germinating seeds produce carbon dioxide.
- The gas in the flask B shows no effect upon coming in contact with limewater, indicating absence of carbon dioxide.
(c) Aim: Experiment demonstrating the fact that seed germination undergo respiration even in complete absence of air.
Procedure & Inference:
- Fill a test tube with mercury that is inverted into a beaker of mercury.
- Into this tube, push some soaked and peeled off pea seeds before inverting into the mercury beaker.
- You will observe that seeds will float up and are entirely girdled by mercury.
- A few days later, few changes are observed. Mercury level drops, presence of some gases are detected in the tube.
- Pour in some KOH into the tube.
- Gas in the tube is absorbed, mercury level rises again, depicting that the gas was carbon dioxide.
- Consequently it is proved that the germinating seeds undergo respiration even in the total absence of air.
(a) Aim: Experiment demonstrating the fact that germinating seeds produce heat.
Procedure:
- Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
- Approximately 200 pea seeds or beans would be used in the experiment. Soak them in water for more than 24 hours.
- Split the seeds into two equal groups approximately.
- One group of seeds are killed by boiling them and washing them with dilute formalin in order to restrict bacterial decay.
- The live germinating seeds need to be placed in flask A and the boiled/killed seeds in flask B.
- Introduce a thermometer into each of the flasks and seal their mouths with cotton wool.
- Take note of the initial reading observed in the thermometer.
- A few hours later, thermometer in the flask A shows a higher reading depicting that the seeds that germinate generate heat.
- Flask B shows no rise in the temperature.
(b) Aim: Experiment demonstrating the fact that germinating seeds produce carbon dioxide.
Procedure:
- Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
- At the base of both the flasks, place wet cotton wool.
- In flask A, take a few soaked seeds of pea, simultaneously take equal quantity of boiled seeds in flask B.
- To flask B, add some carbolic acid so as to inhibit bacterial growth on the dead seeds.
- Seal the flasks with a cork, leave them undisturbed for a couple of days.
- Observe the changes.
- Post few days, germination of seeds in flask A is observed.
- Flask B shows no signs of seed germination.
- Cork is removed to test the gases in each of the flasks. The flask is toppled over a test tube which carries limewater. The test tube is then shaken up.
- Indication of carbon dioxide as expected in flask A is observed when lime water turns milky, thereby depicting that germinating seeds produce carbon dioxide.
- The gas in the flask B shows no effect upon coming in contact with limewater, indicating absence of carbon dioxide.
Procedure & Inference:
- Fill a test tube with mercury that is inverted into a beaker of mercury.
- Into this tube, push some soaked and peeled off pea seeds before inverting into the mercury beaker.
- You will observe that seeds will float up and are entirely girdled by mercury.
- A few days later, few changes are observed. Mercury level drops, presence of some gases are detected in the tube.
- Pour in some KOH into the tube.
- Gas in the tube is absorbed, mercury level rises again, depicting that the gas was carbon dioxide.
- Consequently it is proved that the germinating seeds undergo respiration even in the total absence of air.
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