Question

Amount of CO${}_2$ fixed annually is about

• A. $70\times {10}^{10}$ kg
• B. $70\times {10}^{11}$ kg
• C. $70\times {10}^{13}$ kg
• D. $70\times {10}^{13}$ g.

Answer 1

The correct option is C $70\times {10}^{13}$ kg

Carbon fixation refers to the conversion of inorganic carbon from carbon dioxide into organic carbon. The production of fixed carbon is called primary production. The organisms that can fic the carbon are called as primary producers. Gross primary production (GPP) is the entire amount of carbon fixed by a primary producer.
Net primary production is the GPP minus the organic compounds that have been broken during respiration to carry out cellular processes of that primary producer. The mass of carbon per unit area per year (cm-2yr-1) is the unit to measure GPP and NPP. At about 258 billion tons of carbon dioxide is fixed annually but 40% of the same is lost for respiration. Approximately, 103 billion tons of carbon dioxide is fixed in a year by primary producers.
103 billion tons = $70$ x ${10}^{13}$kg.

So, the correct option is 'Option C'.