This textbook has been designed to meet the needs of B.Sc. Second Semester students of Zoology for the Ranchi University and Other Universities in Jharkhand under the recommended National Education Policy 2020. It comprehensively covers the theoretical and practical aspect of the paper Ecology and Biochemistry. The theory and practical part of this book has been divided into two groups, Group A 'Ecology' and Group B 'Biochemistry'. Group A discusses the evolutionary and functional basis of animal ecology, The students will understand what makes the scientific study of animal ecology a crucial and exciting endeavour. Group B discusses the importance and scope of biochemistry. This book will help the students to learn the structure and biological significance of carbohydrates, amino acids, proteins, lipids and nucleic acids. Relevant experiments corresponding to the theoretical topics and examples have been presented systematically to help students achieve sound conceptual understanding and learn experimental procedures.