The book is a comprehensive introductory text that explores the fundamental principles governing living organisms and the biological processes that sustain life on Earth. Designed for students, educators, and general readers, the book presents a clear and structured overview of modern biology, integrating core concepts with real-world applications.

The book begins with the origin, nature, and diversity of life, followed by an in-depth exploration of the biochemical basis of living systems. It explains how molecules, cells, and genetic mechanisms interact to build and maintain complex life forms. Advanced topics such as human physiological systems, sensory input processing, control of bodily responses, and the role of microorganisms are presented in a clear and accessible manner, supported by examples from daily life and current scientific developments.

A dedicated chapter on genetic engineering introduces readers to modern biotechnology, gene manipulation techniques, and their rapidly growing applications in health, agriculture, and industry. The concluding chapter addresses food, nutrition, and their importance for human health and survival, highlighting the biological principles underlying diet, metabolism, and wellbeing.

With its student-friendly language, conceptual clarity, and strong pedagogical structure, this book serves as an essential foundation for understanding the living world—from the smallest molecules to the most complex systems. It is ideal for high school and undergraduate learners, competitive exam aspirants, and anyone looking to build a solid grounding in biological science.

Dr. Deeksha Dave is working as Associate Professor (Selection grade), Environmental Studies, School of Interdisciplinary and Transdisciplinary Studies, IGNOU. She is M.Sc. (Gold Medalist) and Ph.D. Environmental Sciences from M.L. Sukhadia University, Udaipur. She has a rich experience of more than 15 years of teaching and research in Environmental Studies. She has authored several textbooks on Environmental Studies published by repute publishers. To her credit are several book chapters, research papers and articles in various journals and magazines. She has also participated and presented her research work in several national and international seminars and conferences. She is the recipient of various awards and recognitions at National and International Level.

Dr. Anita Jain (FSE, FSPT) is working as Head, Department of Botany, Vidya Bhawan Rural Institute, Udaipur. She is an active researcher pursuing research in the field of Ethnobotany, Plant Taxonomy and Assessment of Biodiversity since last 25 years. She has prepared Encyclopaedia on Ethnomedicinal and Ethnoveterinary knowledge of tribals of Rajasthan and 'Bibliography of Ethnobotany of India' in 2016. She is NABET approved ‘A’ grade Functional Area Expert in EB and Soil conservation. Recently she visited Denmark as a Part of Indian delegation under the Green strategic Partnership between the govt. of India and Govt. of Denmark as Biodiversity expert for the project “Rejuvenation of Gumaniya Wala-Nala" and development of green space in urban area. She provides consultancy to Forest Department, IWRM, Udaipur, and several private organizations to prepare conservation plan of biodiversity She has guided students to complete their doctorate degree. Dr. Jain has published four books & many chapters in books and published more than 50 research papers in various national and international Journals. Dr. Jain is recipient of several awards & medals. She has successfully completed several research projects funded by reputed organizations. She is also the life member of many academic bodies.

Dr. Vartika Jain, M.Sc. Botany (Gold Medalist), Ph.D., CSIR-UGC NET (JRF), is currently working as an Assistant Professor (Selection grade), at Department of Botany, Govt. Meera Girls’ College, Udaipur, Rajasthan, India. She has been doing research on various dimensions of Ethnobotany, Medicinal Plants, Biodiversity Conservation, Ethno-pharmacology, Phytochemistry and Plant taxonomy for the last 18 years. She has published 90 research articles in peer-reviewed National and International Journals, 29 chapters in books, and written several popular articles in magazines and newspapers. Dr. Vartika has authored five books including the gigantic book entitled “Compendium of Indian Folk Medicine and Ethnobotany” comprising ethnobotanical data of more than 4600 plant species occurring in India. She has participated and presented research papers in several National and International Conferences; delivered invited lectures on diverse topics related to Ethnobiology, Environment conservation, Microvitology etc. and also organized various National and International scientific events. Dr. Jain is the member of reputed Academic Societies and is the recipient of several prestigious awards.

Preface
Chapter 1. Biology of Life
Chapter 2. Life as We Know
Chapter 3. Biochemistry of Life
Chapter 4. Genetics of Life
Chapter 5. Physiological Systems of Humans
Chapter 6. Stimulus Input Through Sense Organs
Chapter 7. Control of Response Outputs
Chapter 8. Microorganisms and Their Impact
Chapter 9. Genetic Engineering and Applications
Chapter 10. Food and Nutrition