Give an activity to show that carbon dioxide is given out during respiration.
Answers
STEP 1- Let us take a wide mouthed bottle. Place some germinating seeds on its bottom . And plug the opening of the bottle with a cork having two holes . Fix a thistle funnel in one whole and close its opening with a cork . In the second hole , insert a delivery tube bent twice . Place the free end of the delivery tube in a test tube filled with water . Place the set up in some dark corner and wrap the bottle with black paper .
STEP 2- Replace the test tube containing water with the test tube having lime water .
STEP 3- Open the cork of funnel and slowly pour water in the bottle till it is almost full. The air from the bottle is displaced through delivery tube into the test tube containing limewater.
Now you can see that the lime water in the test tube turns milky.
This shows that respiration produce Carbon Dioxide as Carbon Dioxide turns limewater milky.
Materials Required : Germinating seed, conical flask, small test tube containing KOH, small thread, bent capillary tube, beaker and cork.
Procedure :
1. Take some germinating seeds of moong dal in a conical flask.
2. Place a small test tube containing KOH solution in hanging position in the flask.
3. Fix a bent capillary tube with one end in conical flask and other end in the beaker containing colored water.
4. Keep the set up for about two hours and observe change in water level in capillary tube.

Germinating seeds Observation :
1. Note the water level position at the start of the experiment.
2. Record the rise of water level in capillary tube.
3. Record water level change in record book.
Result and Inference :
1. Germinating seeds absorb oxygen of conical flask and release CO2
2. Released CO2 is absorbed by KOH
3. Water rise up in capillary to fill space created by gas.
4. Germinating seeds give out CO during respiration.
Precaution :
1. Mouth of conical flask should be air tight with cork.
2. Handle KOH carefully since it is corrosive.
3. Seeds should be germinated and respiring.
4. Hang small test tube with the help of a fine thread.
5. Colored water gives better observation.
