The kinetics of biological reactions depends on the deuterium/protium (D/H) ratio in water. In this work, we describe the kinetic model of biocatalytic reactions in living organisms depending on the D/H ratio. We show that a change in the lifetime or other characteristics of the vital activity of some organisms in response to a decrease or increase in the content of deuterium in the environment can be a sign of a difference in taxons. For animals—this is a curve with saturation according to the Gauss’s principle, for plants—it is the Poisson dependence, for bacteria a weakly saturated curve with a slight reaction to the deuterium/protium ratio toward increasing deuterium. The biological activity of the aquatic environment with reduced, elevated, and natural concentrations of deuterium is considered. The results of the study are presented in different vital indicators of some taxons: the bacteria kingdom—the colony forming units (CFU) index (Escherichia coli); animals—the activation energy of the death of ciliates (Spirostomum ambiguum), embryogenesis of fish (Brachydanio rerio); plants—germination and accumulation of trace elements Callisia fragrans L., sprouting of gametophores and peptidomics of moss Physcomitrella patens. It was found that many organisms change their metabolism and activity, responding to both high and low concentrations of deuterium in water.
