1 Chapter 1: The Science of Biology
Chapter 1 Outline
1.1 What is Life?
- 1.1.1 Composed of Biomolecules
- 1.1.2 Metabolize
- 1.1.3 Composed of Cells
- 1.1.4 Maintain Homeostasis
- 1.1.5 Respond to External Stimuli
- 1.1.6 Grow and Reproduce
- 1.1.7 Evolve
1.2 Scientific Inquiry
- 1.2.1 Scientific Method
- Designing the Scientific Study
- Collecting and Analyzing the Data
- Interpreting the Results
- Other Important Aspects
- Review of the Scientific Method
- 1.2.2 Scientific Theory
- 1.2.3 Reporting Results
Biology is the scientific study of life and its scope is very wide. Earth is home to a multitude of living beings or organisms. Our planet’s conditions – such as temperature, atmosphere, the presence of water and key elements such as carbon and nitrogen – are ideal for life. Tiny single-celled organisms began to appear shortly after the earth was formed over 4 billion years ago and since then there have been explosions of diversity in types of living things. Mammals did not appear until relatively recently, at about 200 million years ago, and only after many of the dinosaur species went extinct at 65 million years ago did the mammals begin to evolve into the forms we are familiar with today, such as deer, wolves, mice, bats, and monkeys. This book focuses on the study of the human species, which began its evolutionary pathway separate from apes only 6-8 million years ago, long after the first mammals appeared. Our modern human appearance did not appear until about 250 thousands years ago. Thus, while we focus on human biology in this book, we must recognize the close relationship between humans and other species. Not only do we share a recent evolutionary history, we also share the same biological foundations that will form the cornerstones of this book.
Before we dive into those biological foundations, we need to define what we are studying and how we study it. What is life? How do we study it scientifically?
1.1 What is Life?
Learning Objectives
You will be able to describe these characteristics of organisms:
- Composed of biomolecules
- Metabolize
- Composed of cells
- Maintain homeostasis
- Respond to external stimuli
- Grow and reproduce
- Evolve
Biology is the science that studies life. What exactly is life? This may sound like a silly question with an obvious answer, but it is not easy to define life. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others. It turns out that although viruses can attack living organisms, cause diseases, and even reproduce, they do not meet the criteria that biologists use to define life.
1.1.1 Composed of Biomolecules
All living things are composed of four basic types of biomolecules, most of which are probably familiar to you because three of them are nutrients that you obtain from your diet: carbohydrates, proteins, and lipids (fatty acids). The fourth, nucleic acids, includes deoxyribose nucleic acid or DNA, which