Mathematics has always benefited from its involvement with developing sciences. Mathematical biology is a fast-growing, well-recognised, albeit not clearly defined, subject and is the most exciting modern application of mathematics. The increasing use of mathematics in biology is inevitable as biology becomes more quantitative. The complexity of the biological sciences makes interdisciplinary involvement essential. For the mathematician, biology opens up new and exciting branches, while for the biologist, mathematical modelling offers another research tool commensurate with a new powerful laboratory technique but only if used appropriately and its limitations recognised. Mathematical biology research, to be useful and interesting, must be relevant biologically. The mathematical model is a translation of a real-life problem in the world into a mathematical description. This book contains non-linear mathematical models of real-world problems with different functional responses.