Plants need to absorb many necessary nutrients from the nutrient solution or–in the case of traditional agriculture–the soil. However, plants can create some of their own food. Plants use the process of photosynthesis to create food for energy. Carbohydrates are produced from carbon dioxide (CO2) and a source of hydrogen (H)–such as water–in chlorophyll-containing plant cells when they are exposed to light. This process results in the production of oxygen (O).