Contents: Discrete process in biology: The theory of linear difference equations applied to population growth -- Nonlinear difference equations -- Applications of nonlinear difference equations to population biology -- Continuous processes and ordinary differential equations: An introduction to continuous models -- Phase-plane methods and qualitative solutions -- Applications of continuous models to population dynamics -- Models for molecular events -- Limit cycles, oscillations and excitable systems -- Spatially distributed systems and partial differential equation models:An introduction to partial differential equations and diffusion -- Partial differential equation models in biology -- Models for development and pattern formation in biological systems.