Carbon assimilation and rate of carbon flow through metabolic pathways will increase, and will thus raise the potential for plant growth. Atmospheric carbon dioxide provides, through the processes of photosynthesis, all of the raw materials for biological activity on earth. The major storage products of photosynthesis are sugars, starch, proteins, and fats. These are harvested from plants and form the basis of all animal and human diets. Agriculture, the single biggest industry in the world, depends on photosynthetic metabolism for all of its products. The established principles of photosynthetic carbon metabolism are unlikely to change with increased carbon dioxide (CO2). However, the rate of CO2 assimilation, its duration, and the end products should be altered by more CO2. The many steps of the photosynthetic carbon cycle seem well established, but the details, especially regulation, are subject to future investigation. Photorespiration has several functions during normal photosynthesis.