Home >> Science & Nature >> Science

What Does CO2 Help With in Photosynthesis?

Photosynthesis is a complex process in which plants use water, air and sunlight to create energy. Its most common form involves two steps, the light reaction and the dark reaction. Carbon dioxide is essential in the dark reaction. Its involvement with the life of plants has broad implications not just in creating the oxygen we breathe and the food we eat, but also in the danger of deforestation.

The Light Reaction
- The sun provides light energy used by plants.
  
  In the first part of photosynthesis, chlorophyll and other pigments in the plant, along with light energy and water, make ATP, or adenosine triphosphate, which provides usable chemical energy for use in the second reaction. O2, the two-atom oxygen molecule animals need to breathe, is released into the air. This is called the light reaction both because it requires light to work and because it converts light energy into chemical energy that can be transported and used by the plant.
The Dark Reaction
- In the second part of photosynthesis, ATP's energy is used in combination with CO2 from the air breathed in by the plant and rubisco, a plant enzyme, to create sugars. This reaction, which involves a sugar-making process called the Calvin cycle, is called the dark reaction because it doesn't require direct light to happen. However, in most plants, it can only happen while the plant is exposed to light because that's when the ATP is being produced (and therefore available) to aid the process.
The Carbon Cycle
- All of our food energy is derived from plant sugars.
  
  In photosynthesis, CO2 is essential. It provides the carbon and oxygen necessary for the formation of sugar molecules. The sugar provides energy for the plants as well as energy -- in the form of food -- for us. This importance of CO2 is mirrored in the world at large: without CO2, we'd have no green plants. And without these plants, we'd have no oxygen to breathe and no food to eat. Plants breathe in CO2, trap it in sugars and breathe out O2, while animals breathe in O2 and breathe out CO2. This is known as the carbon cycle.
Rising CO2 Levels
- Untold numbers of species are threatened by global warming.
  
  However, right now there is too much CO2 in the air. CO2 is produced by many of modern society's industrial and commercial practices, including driving and flying. Between deforestation and overproduction of CO2, our planet is not able to keep balance in the carbon cycle. The presence of too much CO2 traps heat, resulting in global warming. Both reforestation, which means more photosynthesis and CO2 absorption, and the reduction of CO2 emissions are necessary in reducing global warming.

Science