6. Biogeochemical cycles. (Hessler, A. M. (2011) Earth\'s Earliest Climate. Natu

Question

6. Biogeochemical cycles. (Hessler, A. M. (2011) Earth's Earliest Climate. Nature Education Knowledge 3(10):24; Mackenzie, F. T. (1999) Global Biogeochemical Cycles and the Physical Climate System, Global Change Instruction Program; lecture slides) Isotope fractionation by living organisms is used extensively to identify biological intervention into geochemical processes. The isotopes of C, S, and N have been the most used for this purpose, with the biological "signature" being an increase in the light isotope relative to the heavy isotope. Recent studies have analyzed the isotopic composition of very old rocks ( billion years) in order to determine the timing of two important events: (i) the beginning of biological activity, and (ii) the advent of oxygen production by photosynthesis. Discuss in a short paragraph some the pitfalls and problems that might be associated with this kind of analysis

Explanation / Answer

Photosynthesis require an exchange of gases with the planet.absorption of co2 and the excretion of o2.,which is by product of photosynthesis.these gases are obtained and released through tiny opening called stomata.stomata are opened a certain amount of water escapes,posing a problem for plant living in environment.that have a limited amount of water to begin with.

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