Experiment to Prove the Importance of Carbon Dioxide in Photosynthesis:



Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose and oxygen. It is a vital process for the survival of living organisms on Earth. In this experiment, we will demonstrate the importance of carbon dioxide in photosynthesis by comparing the growth of plants in the presence and absence of carbon dioxide.



- Two potted plants of the same species
- Transparent plastic bags
- Rubber bands
- Water
- Light source
- Measuring cylinder
- Sodium hydroxide (NaOH)
- Test tubes
- Stopper with a delivery tube



1. Select two healthy potted plants of the same species and ensure they are exposed to similar light conditions.
2. Cover one plant with a transparent plastic bag and secure it with a rubber band. This will create a closed environment.
3. Leave the other plant uncovered as a control group.
4. Place both plants in an area where they can receive ample sunlight.
5. Water both plants equally, ensuring that they have sufficient moisture.
6. Leave the plants undisturbed for a few days, allowing them to acclimate to their environments.
7. After a few days, prepare a sodium hydroxide (NaOH) solution by dissolving a small amount of NaOH in water. This solution will absorb carbon dioxide.
8. Take a measuring cylinder and fill it with water.
9. Place the stopper with a delivery tube into the measuring cylinder, ensuring that the tube is submerged in the water.
10. Insert the other end of the delivery tube into the plastic bag covering the experimental plant.
11. Gently blow into the bag to expel any remaining air and ensure it is airtight.
12. Add a few drops of phenolphthalein indicator to the NaOH solution. The indicator will turn pink in the presence of carbon dioxide.
13. Carefully pour the NaOH solution into a test tube and close it with a stopper.
14. Place the test tube in a beaker of hot water to promote the absorption of carbon dioxide.
15. Observe the changes in the color of the indicator in the test tube over time.



1. The uncovered control plant will continue to grow and maintain its green color.
2. The experimental plant, covered with the plastic bag, will gradually turn pale or yellowish due to the absence of carbon dioxide.
3. The phenolphthalein indicator in the test tube will turn pink, indicating the absorption of carbon dioxide by the NaOH solution.



This experiment demonstrates the importance of carbon dioxide in photosynthesis. The covered plant, which lacked access to carbon dioxide, displayed stunted growth and pale coloration. In contrast, the control plant, which had access to carbon dioxide, continued to grow and remained healthy. The presence of carbon dioxide in the atmosphere is crucial for plants to carry out photosynthesis effectively and produce glucose, which serves as a source of energy for all living organisms.