Biology is the scientific study of life and living organisms.1 It is a broad natural science that explores the physicochemical aspects of life, including the structure, function, growth, origin, evolution, and distribution of living things.2
The study of biology spans multiple levels of organization, from the molecular level up to the biosphere.3
Major Branches of Biology
Biology is a vast field broken down into many specialized branches.4 The three traditional main divisions are:
- Botany: The study of plants.5
- Zoology: The study of animals.6
- Microbiology: The study of microorganisms (like bacteria, viruses, and fungi).7
Other significant branches include:
- Genetics: The study of heredity, including genes, DNA, and how traits are passed down.8
- Ecology: The study of how organisms interact with each other and their environment.9
- Anatomy: The study of the structure of organisms and their parts.10
- Physiology: The study of the function of organisms and their parts.11
- Molecular Biology: The study of the molecular basis of biological activity within and between cells.12
- Cell Biology (Cytology): The study of the cell, the basic unit of life, including its structure and function.13
- Evolutionary Biology: The study of the evolutionary processes that produce the diversity of life on Earth.14
Unifying Concepts in Biology
All of biology is centered on a few fundamental, unifying themes:
- The Cell as the Basic Unit of Life: All organisms are composed of one or more cells.15
- Homeostasis (Regulation): Living organisms maintain a stable internal environment necessary for survival.16
- Heredity/Genes: Genetic information, encoded in DNA, is passed from parent to offspring, providing instructions for growth, development, and function.17
- Evolution: Organisms change over time, and new species arise through the process of natural selection, explaining the vast diversity of life.18
- Energy Processing: All organisms use a source of energy (like sunlight or food) to power their metabolic activities.19
Understanding these concepts helps explain the fundamental workings of life across all species.
The video Introduction to Biology: Crash Course Biology #1 provides an excellent overview of what biology is and the characteristics that define life.