Most biological questions are network questions because biological systems are large and complicated. Stochastic processes arise naturally (1) as external forcing to which the system must adapt; (2) as an external probe of system dynamics; (3) as a representation of underlying biological diversity; (4) as a fundamental mechanism for a biological object to achieve a specific purpose. Examples will be given. Biological networks have myriad control mechanisms that ensure that some variables remain stable while other fluctuate wildly. How can one tell from the network (and the dynamics) which variables are the stable ones? Many examples of (4) will be given including gene expression and volume transmission in the brain. To find exciting and new mathematical questions, one should focus on how specific biological systems work.