1. Take a conical flask. Fit a two holed rubber cork tightly into its mouth and insert glass tubes into the two holes.
2. Fit a rubber tube on one of the glass tubes and a funnel on the other. If the funnel does not sit tightly on the glass tube, make a funnel with an ink dropper.
3. Fill a test tube about one-fourth with lime water and dip the rubber tube into it.
4. Now add water to the funnel drop by drop. Keep adding water till the conical flask is filled one-fourth with water. Observe the test tube carefully while you add water.
5. You find no change in the colour of lime water.
6. Now remove the water from the conical flask and put some flowers and buds in it. Fit a cork on the flask and let it stand for half an hour.
7. Now add water drop by drop to the conical flask through the funnel as you did in the previous experiment. Look carefully at the test tube while doing so.
8. The lime water turns milky indicating the release of carbon dioxide.
9. This is how plants respire. They take oxygen and release carbon dioxide.
