The Calvin cycle uses carbon dioxide, water and adenosine triphosphate, or ATP, to produce high-energy sugars such as glucose, fructose and sucrose. It is one of the core processes of photosynthesis in plants, and the ATP it uses is ultimately produced from sunlight in other parts of the chloroplast. In certain plants, cells with chloroplasts are paired, with one primarily producing ATP, leaving the other for the Calvin cycle.
The Calvin cycle is used by algae and cyanobacteria as well as plants. Because it is a part of all oxygen-producing photosynthesis on Earth, it is among the most important of all biological processes, and the biological molecules it uses are among the most common. Almost all organisms ultimately depend on photosynthesis. The sugars created in the carbon cycle are further processed into all the carbohydrate compounds that compose plant structures, serving as food for herbivores.
In most plants, carbon dioxide is taken in by leaves shortly before it is used in the Calvin cycle to make sugars. In certain plants native to arid environments, such as the pineapple, carbon dioxide is taken in at night and stored within malic acid; it's then used during the day, permitting the plant to shut off its stomata and preserve water in the heat.