Leaves

• The leaves are the parts of a plant that serve as collectors for light and CO2. This is where the bulk of photosynthesis occurs. They are comprised of the upper and lower epidermis, the veins (vascular bundles), the mesophyll and the stomates. The epidermis acts much like human skin to protect the inner parts of the leaves. The veins move nutrients and water throughout the leaves and the mesophyll is where photosynthesis occurs, since it contains the chloroplasts that produce chlorophyll. The stomates are pore-like holes that allow the plant to absorb CO2 and release oxygen. They are also how plants perspire by releasing water vapor.
  
  

Chlorophyll

• Chlorophyll is a green chemical that is vital to the process of photosynthesis. It helps in the conversion of light into energy. Chlorophyll blocks some of the wavelengths of light, while letting through the red and blue wavelengths needed by the plant. Other substances, such as beta-carotene, also participate in the light filtering process. The chemical ATP (adenosine triphosphate) stores this light energy inside the plant.
  
  

Photosynthesis

• CO2 enters the leaf through the stomates and into the chloroplast. There the CO2 mixes with the ATP and water. A chemical reaction occurs that pulls the carbon from the CO2 to form sugar, leaving the oxygen behind as a byproduct. The stomates then release the oxygen back into the atmosphere, while the sugar is sent through the veins to be used as an energy source by the plant.
  
  

Significance

• Without any of the three main ingredients of light, CO2 and water, photosynthesis cannot occur and plants cannot make food for themselves. That is why plants die when they do not get one of these vital elements. Without plant life, which is the basis of the food chain, there is no life. Indirectly, CO2 sustains all life on earth.
  
  

Misconceptions

• While too little CO2 can be devastating for plants and CO2 supplements can increase plant growth and yields, high levels of CO2 can create problems, as well. According to an article at ScienCentral, scientists have found that crops like soybeans that have been purposely exposed to elevated levels of CO2 experienced increased attack from insects, such as the Japanese beetle. When they are exposed to high levels of CO2, plants do not produce as much protease inhibitor, a natural chemical defense mechanism that affects the digestion of the insect and suppresses how much of the plant they eat. This attracts insects to these plants and increases the amount of the plant they eat, which increases the lifespan and number of insects in that area, which compounds the problem.