Biology in time and space : a partial differential equation modeling approach This book tells the story of biological objects by using a multi variable differential equation approach and it covers both population level dynamics as well as cell biology and physiology. There are fourteen chapters and several appendices in this book. Each chapter contains around ten to thirty exercises with selected solutions provided in an appendix at the end. The Matlab code used in each chapter is also summarized at the end of the book. The first Chapter is devoted to background material including dynamical systems and stochastic processes. Chapter Two explains conservation law. Chapter Three and Chapter Four revolve around diffusion equations and their realization. Chapter Five discusses solutions of diffusion equations both analytically and numerically. Chapter Six is devoted to diffusion and reaction processes. Chapter Seven and Chapter Eight look at the derivation and analysis of the bistable equation. Chapter Nine and Chapter Ten study advection reaction models and advection with diffusion. Chapter Eleven to Fourteen cover a number of interesting and important biological processes. They include for example amoeba aggregation tiger bush stripes cell polarity invasive species quorum sensing and flocking. The book is suitable for the level of advanced undergraduate students and above.