What Happens to Carbon Dioxide During Photosynthesis?

By Kimberly Turtenwald; Updated April 24, 2017
Plants need carbon dioxide for the photosynthesis process.

Plants use the process of photosynthesis to change carbon dioxide into oxygen, as well as to create food for themselves. This makes plants a good complement to the human race as humans breathe out carbon dioxide, which the plants then turn it into the oxygen humans need to live. Plants and humans need each other to survive.


Humans and animals exhale carbon dioxide as a byproduct of respiration. Plants extract the carbon dioxide from the air and use it in the photosynthesis process to feed themselves. Since plants do not breathe as humans and animals do, the carbon dioxide enters the leaves of the plant through small pores called stomata. Once the carbon dioxide enters the plant, the photosynthesis process can begin with the help of sunlight and water.

Photosynthesis Process

During the photosynthesis process, the carbon dioxide is combined with water to allow the plant to extract what it needs for food. The plant uses sunlight as energy to perform this chemical reaction. Carbon dioxide, known as CO2, and water, or H2O, are separated into their individual molecules and combined into new products. Oxygen, or O2, is released from the plant into the air for the use of humans and animals. The plant also produces C6H12O6, which is similar to glucose and is used by the plant as food.

Food Storage

Because plants often receive more carbon dioxide and water than they need to sustain their own lives, extra food is produced. Plants then store this food in other areas of the plant. In the cases of some plants, this food is stored in the fruits and vegetables that humans and animals eat. Therefore, the carbon dioxide taken into plants also helps provide food for humans and animals in addition to themselves.

Importance of Photosynthesis

In addition to making food for plants to survive, photosynthesis is an important part of the life cycle of all living things. Most living things require oxygen to survive. Oxygen is in limited supply in the atmosphere. Therefore, if there was no way to transform the carbon dioxide emitted by living things back into oxygen, life would be unsustainable in the long term. Because plants are able to use the carbon dioxide and change it back into oxygen, life is able to continue for all living things, forming an important cycle.

About the Author

Kimberly Turtenwald began writing professionally in 2000. She has written content for various websites, including Lights 2 You, Online Consultation, Corpus Personal Injury and more. Turtenwald studied editing and publishing at Wisconsin Lutheran College.