Textbook in PDF format The book examines biological processes vital for organism survival through a chemical lens. Integrating core organic chemistry concepts, such as structural analysis and synthesis, explores how plants and animals produce and utilize toxic organic molecules for growth, survival, and reproduction. The book focuses on the intricate structures, vital functions, and synthesis pathways of toxic secondary metabolites from plants and animals, illustrating toxic substances' intricate chemical relationships and biological significance. The book addresses the following main questions: Why do animals and plants accumulate these toxic substances? What structures do these compounds have? What effects can they have on man? Can they be prepared in the laboratory and used for medicinal purposes? This book delves into the fascinating world of toxic secondary metabolites in plants and animals, bridging chemistry and biology to unravel their roles in survival. With an interdisciplinary approach, it is a valuable resource for researchers, students, and professionals in phytochemistry, organic chemistry, and medical sciences