The purpose of this book is to give students of zoology a concise account of the kind of practical study of bio statistics and computer applications, biochemistry, biophysics, environmental biology and toxicology. Sufficient information is given in the form of notes, diagrams, formulas and calculations. I am indebted to specifically thank to all my colleagues for their continuous encouragement to prepare this book in stipulated time. Criticism and suggestions for further improvement shall be gratefully acknowledged. I am immensely thankful to the management and principal of J.K.K. Nataraja college of arts and science, Komarapalayam, for their kind co-operation.

I am Dr. S.Umavathi working as an Assistant Professor and Head, PG & Research Department of Zoology, J.K.K.. Nataraja College of Arts and Science, Komarapalayam-638 183, Namakkal (Dt), Tamil Nadu, India. I guided 7 M.Sc student projects,12 M.Phil scholars and now guiding 3 Ph,D scholars.