Prove that Co2 is necessary
Today we will discuss about an experiment which proves, why carbon dioxide is necessary for photosynthesis.
What is carbon dioxide
Carbon dioxide is a gas formed by carbon and oxygen. It’s a colorless gas.
Steps for experiment.
1. Take a healthy plant which have tall and parochial leaves. Then place the plant in the dark area for 3-4 days to destarch plant leaves.
2. Take a bottle made up of glass having a wide mouth. Then put some potassium hydroxide solution in glass bottle. This KOH solution absorb all carbon dioxide gas which is present in glass bottle.
3. Now, take a cork of rubber, and the cork should fits completely and tightly into the mouth of the glass bottle and then cut it into 2 halves.
4. Put a leaf which is destarched ( leaf of the healthy plant ) in between the two halves of the cork ( mentioned in step 3 ) and then fit the cork properly and tightly in the mouth of the glass bottle.
The upper half side of the leaf should be placed outside the glass bottle and only the lower half side of the leaf should be placed inside the glass bottle.
5. Keep the healthy plant in the sun light for 3-4 day such that outer part of leaf will get co2 but the lower part of leaf will not get co2.
( Because all the carbon dioxide gas which is present inside the glass bottle is absorbed by potassium hydroxide. ) And there is no way from where fresh air can come outside.
6. Now, pluck this leaf from the healthy plant and then boil it in the C2H5OH or you can you any alcohol.
Boiling in alcohol will remove the chlorophyll.
7. Take the colorless leaf ( which is decolourised ) and wash it with H2O because we have to remove chlorophyll pigment properly.
8. Take a colorless leaf and then pour iodine solution in it and then observe the change in it.
9. The upper part of the leaf will turned in black blue colour because it contain starch but lower part of the leaf doesn’t show any colour change because it doesn’t have starch present in it.