Carbon dioxide is essential for Photosynthesis


To show that carbon dioxide is essential for photosynthesis. 



Getting the proper nutrition and energy is essential for all living creatures, including humans and animals! It is the key to staying alive and healthy. Carbon dioxide is one of the essential components in this process. It helps in the production of food and energy for survival. 

What is carbon dioxide?  

  • It is a colourless gas composed of one carbon atom bonded with two oxygen atoms.  
  • During the process of photosynthesis, plants absorb carbon dioxide to release oxygen and water. 
  • It serves as a raw material source to produce organic compounds such as sugars (like starch) as a food material. 


  • Photosynthesis is the process where organisms convert light energy into chemical energy. 
  • Carbon dioxide plays a major role in converting light energy into chemical energy through simple sugar(glucose) and liberating oxygen and water.  



                                                                                  Fig.1 Conversion process of photosynthesis 

Steps involved in the photosynthesis 

  • Light energy is absorbed by chlorophyll. 
  • The conversion of light energy into chemical energy occurs by reducing the observed carbon dioxide into carbohydrates, and at the same time, water molecules are separated into hydrogen and oxygen. 
  • The liberated products, oxygen, and water are released from the stomata of the plants. 
  • The liberated sugar is stored in the form of starch in plant roots. 



                                                                                                    Fig.2 Process of photosynthesis 


The role of carbon dioxide in the process of photosynthesis 

S. No  Role of role of carbon dioxide  Benefits 
1 For glucose production  Carbon dioxide combines with light energy to produce glucose molecules, which also play a role in storing food.  
2 Regulation of Photosynthesis Rate  The increased availability regulates the rate of photosynthesis, resulting in a significant production of oxygen. 
3 Role in Global Carbon Cycle  It is a key component in the global carbon cycle, facilitating the exchange of carbon and oxygen within the ocean and terrestrial ecosystems through the process of photosynthesis. 


Usage of KOH solution 

  • In this experiment, the leaf is dipped into the KOH solution to avoid leaf exposure in the atmosphere and absorbs carbon dioxide in and around the test tube and leaf.  

Usage of alcohol 

  • The alcohol is used to extract or separate the chlorophyll (the green pigment) and allows for clear observation while using indicator medium. 

Usage of iodine solution 

  • It serves as an indicator to reveal the presence of starch by the colour change of blue-black in the sample thereby demonstrating the process of photosynthesis.  


Learning Outcomes 

Students learn and understand,  

  • The concept of photosynthesis. 
  • The mechanism and conversion of photosynthesis.  
  • The role and the benefits of carbon dioxide in photosynthesis.  
  • The usage of chemicals in this experiment.