Carbon dioxide photosynthesis production, primary

Many estimates of total terrestrial net primary production are available, ranging between 45.5 Pg C/yr (Lieth, 1972) and 78 Pg/yr (Bazilevich et al., 1970). Ajtay ef oZ. (1979) have revised the various estimates and methods involved, they also reassess the classifications of ecosystem types and the extent of the ecosystem surface area using new data and arriving at a total NPP of 60 Pg C/yr. Gross primary production is estimated to be twice net primary production, i.e., 120 Pg C/yr. This implies that about 60 Pg C/yr are returned to the atmosphere during the respiratory phase of photosynthesis. It is well known that carbon dioxide uptake by plants follows daily cycles most plants take up CO2... 

Growth can be defined as the production of organic matter by increase in size or volume. This process involves the uptake of water, carbon dioxide and minerals. In plants, growth is made possible by the process of photosynthesis, which produces the sugars (as primary components) from which compounds such as starch, cellulose, amino acids and proteins are derived. 

In the atmosphere carbon exists mainly as carbon dioxide (Fig. 6.1), which is taken up by plants during photosynthesis.The amount of solar energy captured by plants during photosynthesis is referred to as gross primary production and can be measured by the amount of carbon dioxide that has been fixed. As noted in Section... 

The addition of exogenous substrates of primary metabolites to organisms in culture (or blocking of particular steps of biosynthetic pathways) can result in overproduction of either primary or secondary compounds. Gross primary production by plants exceeds net primary production. Additionally as much as 38% of carbon fixed by photosynthesis may be lost through photorespiration. The process of cyanide-resistant respiration represents an obvious nonaccumu-lative mechanism by which plants can divide any overflow into carbon dioxide (Waterman and Mole, 1989). 

The primary importance of photosynthesis as an energy converting reaction had to await the development of the concept of chemical energy. In 1845, Robert Mayer recognized that the energy of sunlight was converted by photosynthesis to the stored chemical potential of the products. Thus today, we write the equation for the photosynthesis of carbohydrates from water and carbon dioxide ... 

Starch is one of the most abundant polysaccharides in nature. It is synthesized as a result of the photosynthesis process from carbon dioxide and water, and is then accumulated in seeds, tubers, and other parts of the plant [1,46], The primary raw material for starch production in the worldmarket is maize (81% of the global production of starch). Lesser, though significant, importance in this case is shared by wheat and potato (9 and 5% of global production, respectively). On the industrial scale, tapioca, rice, and waxy maize are also used. The total production of starch does not exceed 5% [11,89,91]. The global production of starch in the year 2(X)5 reached about 60 million tons [89]. 

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