A C3 is a plant that fixes carbon dioxide into a three-carbon compound before it enters into the Calvin cycle. Most C3 plants are kept in areas where CO2 concentration is high, also in environments where temperature and light intensity are moderate. If these requirements are not met photorespiration may occur. Photorespiration will cause loss of CO2 in the C3 plant. Potatoes are pictured here because they come from a potato plant that is a C3 plant.