Respiration in Plants — Question 6

1. Aim — Experiment demonstrating the fact that germinating seeds produce heat.

Procedure —

1. Name two thermo flasks as 'A' and 'B', keep them aside
2. Approximately 200 pea seeds or beans would be used in the experiment. Soak them in water for more than 24 hours.
3. Split the seeds into two equal groups approximately
4. One group of seeds are killed by boiling them and washing them with dilute formaline in order to restrict bacterial decay
5. The live germinating seeds need to be placed in flask A and the boiled/killed seeds in flask B.
6. Introduce a thermometer into each of the flasks and seal their mouths with cotton wool.
7. Take note of the initial reading observed in the thermometer.

Inference —

1. A few hours later, thermometer in the flask A shows a higher reading depicting that the seeds that germinate generate heat.

2. Flask B shows no rise in the temperature.

3. Aim — Experiment demonstrating the fact that germinating seeds produce Carbon dioxide.

Procedure —

1. Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
2. At the base of both the flasks, place wet cotton wool.
3. In flask A, take a few soaked seeds of pea, simultaneously take equal quantity of boiled seeds in flask B.
4. To flask B, add some carbolic acid so as to inhibit bacterial growth on the dead seeds.
5. Seal the flasks with a cork, leave them undisturbed for a couple of days.
6. Observe the changes.

Inference —

1. Post few days, germination of seeds in flask A is observed.

2. Flask B shows no signs of seed germination.

3. 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.

4. Indication of carbon dioxide as expected in flask A is observed when lime water turns milky, thereby depicting that germinating seeds produce carbon dioxide.

5. The gas in the flask B shows no effect upon coming in contact with limewater, indicating absence of carbon dioxide.

6. Aim — Experiment demonstrating the fact that seed germination undergoes respiration even in complete absence of air

Procedure and Inference —

1. Fill a test tube with mercury that is inverted into a beaker of mercury.
2. Into this tube, push some soaked and peeled off pea seeds before inverting into the mercury beaker.
3. You will observe that seeds will float up and are entirely girdled by mercury.
4. A few days later, few changes are observed. Mercury level drops, presence of some gases are detected in the tube.
5. Pour in some KOH into the tube.
6. Gas in the tube is absorbed, mercury level rises again, depicting that the gas was carbon dioxide
7. Consequently it is proved that the germinating seeds undergo respiration even in the total absence of air.