We are interested in the effects of fluctuation which are observed in biological phenomena. There is a big variety in the appearance of the effects, however many of mathematical descriptions have much similarity. The most elemental and basic fluctuoation can be realized by white noise, either Gaussian or compound Poisson type. This fact leads us to discuss functions of white noise, call them white noise functionals of either Gaussian or Poisson type, which may well describe biological systems mathematically. We then consider the analysis of those functionals. The analysis in question will be the causal calculus, since the biological phenomena are to be evolutional in many cases, that is, they are developing as the time goes by. To be more concrete, some of the following topics in mathematical biology will be discussed.\par 1) Applications of the Wiener expansion and of the Hellinger-Hahn theory, \par 2) Construction of innovations of biological, evolutional phenomena with fluctuation. It is often helped by a method of using the infinite dimensional rotation group, \par 3) Creation and annihilation operators applied to random evolutional phenomena, irreversibility and other properties,\par 4) Genralizations of the Lotka-Volterra equation with fluctuation. 5) Functionals of Poisson noise with application to biology. 6) Others.