Life is an improbable event. Consider, for example, the complex structures of organisms, not only at the macroscopic level, but also at the microscopic and atomic levels. These ordered structures can be formed and maintained only by the expenditure of energy. Within the ecosystem that we call the earth, the organic nutrients necessary to sustain the life of heterotrophs such as us are provided directly and indirectly by photosynthesis. In both quantitative and qualitative terms photosynthesis is the most significant biological process on Earth. Citations are important for a journal to get impact factor. Impact factor is a measure reflecting the average number of citations to recent articles published in the journal. The impact of the journal is influenced by impact factor, the journals with high impact factor are considered more important than those with lower ones. This information can be published in our peer reviewed journal with impact factors and are calculated using citations not only from research articles but also review articles (which tend to receive more citations), editorials, letters, meeting abstracts, short communications, and case reports. Approximately 2 x 1011 tons of carbon dioxide are converted to organic compounds each year. It is to photosynthesis in prehistoric times that we owe the reserves of fossil fuels. The oxygen that we breathe is a direct result of photosynthesis, now and in prehistory. If the earth were an isolated system in a thermodynamic sense, life would be in jeopardy in that the energy reserves for life would be consumed. Without the input of energy from a source external to the earth, the planet must tend toward achieving equilibrium within its environment. Although some bacteria carry out photosynthesis without the evolution of oxygen, this article deals solely with oxygenic photosynthesis that takes place in higher plants and algae. In a purely formal sense, oxygenic photosynthesis may be represented as the reverse of the oxidative breakdown of a six-carbon carbohydrate, such as glucose. An equation that describes photosynthesis in part illustrates this relationship:where C6H12O6 refers to a six-carbon sugar. This equation in reverse describes the oxidative catabolism of a six-carbon sugar such as glucose. Under standard conditions, the complete oxidation of glucose liberates 686 kcal/mol; the synthesis of a mole of glucose from carbon dioxide and water thus minimally requires the input of an equivalent amount of energy. In photosynthesis, visible light provides this energy. When it is considered that the only source of carbon for the tens of thousands of organic compounds synthesized in green plants is from the assimilation of carbon dioxide by means of photosynthesis, the inadequacy of Eq. (5) to describe photosynthesis, despite its usefulness, is readily apparent.