Experiment to show that Carbon dioxide is necessary for Photosyntesis

 

MATERIAL AND APPARATUS:
Potted plant, 2 conical flasks, Soda lime, cork, Vaseline, water, iodine solution.


 PROCEDURES
 1. Destarch a plant (potted plant) by keeping it in darkness for two continuous days.

 2. Pluck a leaf from the plant and test it for starch. If starch is present then keep the plant in darkness for some more days. If starch is absent continue with step 3.

3. Enclose one leaf in a conical flask labelled A, containing sodium hydroxide. Enclose another leaf in another conical flask labelled B, without sodium hydroxide. Pass the leaf stalk through a split cork which has been vaselined to keep the flask air tight. The sodium hydroxide removes or absorbs all the carbon dioxide from the flask A.

4. Support each flask with a clamp. Place the potted plant in sunlight for 3-4 hours..

5. Remove the leaf from each flask and test each of them for starch.




OBSERVATION
When iodine solution was added to the leaf from flask A, the brown colour of iodine solution remained unchanged.

For the leaf in flask B, the colour of the iodine solution changed into blue black.




EXPLANATION:
 In flask A, the colour of iodine solution remained brown. This is because starch was absent from the leaf of flask A.
Starch was absent from the leaf in flask A because it did not undergo photosynthesis.
Photosynthesis did not go on because there was no carbon dioxide in flask A. The carbon dioxide was absorbed by the sodium hydroxide.

In flask B, the colour of the iodine solution turned blue black. This is because starch was present in the leaf of flask B. Starch was present because it underwent photosynthesis. This was because flask 3 contained carbon dioxide.
 

CONCLUSION
Carbon dioxide is necessary for photosynthesis.

Comments

  1. Thank you very much it helps me alot to do my biology project work I got full marks in this thanks again...

    ReplyDelete
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    ReplyDelete
  3. Keep it up,u have good explanation

    ReplyDelete

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