• How is isotope fractionation related to the primary 

 structure of the rate-determining enzyme? 



• What determines the upper rate of growth and production 

 of an organism? 



• Can specific molecular indices of growth be developed for 

 eucaryotic as well as procaryotic organisms? 



• How do biogeochemical processes related to metabolism 

 change with the growth of organisms? 



• How can we improve our measurements of metabolic activity 

 of anaerobic organisms in natural ecosystems? 



• How can we differentiate between maintenance energy and 

 energy used for net growth in organisms in nature? 



Some specific suggestions are described in Appendix II. 



Community Structure 



Each organism, or more precisely, each strain or species, 

 occupies a niche, which may be conceived as a multidimensional 

 phase space in which the organism lives and reproduces. For most 

 organisms their potential niche, the portion of the phase space in 

 which they could live, is much larger than their actual niche. 

 Existence and reproduction outside the niche are impossible without 

 genetic alteration. 



Although the earth underwent two complete ice ages over the 

 last 160,000 years, the composition of the atmosphere remained 

 relatively constant. Because of this relative stasis, it was 

 assumed that the relative rates of critical biogeochemical cycles 

 also remained relatively constant. However, this does not mean 

 that ecosystem structure has remained constant, because the 

 organisms which were negatively affected by the climatic changes 

 were selected against and eventually replaced by more functionally 

 redundant organisms. However, the environmental changes forecast 

 by the present global climate models are so fast, compared to the 

 rate of previous climate changes, that it is unclear whether biotic 

 components can adapt rapidly enough to maintain a relatively steady 

 state in the ecosystem's functioning. 



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