Two curves characterizing a set of realizations of Markov stochastic process were analyzed: the expected curve and the predicted curve. Although the definition of the predicted curve is new, curves with the same formulas are known in science as so-called deterministic models. This can be seen in the examples of the most well-known models in biology: logistics, Lotka-Volterra and Hardy-Weinberg. Attention was paid to the efficiency of calculating these both curves and their interpretation as the central tendency characteristics of Markov stochastic processes.