Biology as a Science
Define life science as the study of living systems and distinguish observation, inference, hypothesis, theory, and law. Use biological examples to show how scientific explanations are revised with evidence.
A lesson of Biology, in Biology Foundations and Scientific Practice, about 10 minutes.
By the end of this lesson, you will be able to define the hallmarks of life, distinguish observation from inference, classify hypotheses and theories, and explain how scientific explanations are revised with evidence.
The Big Idea
Biology — the scientific study of life — is built on a specific way of knowing: making observations, forming testable hypotheses, collecting evidence, and revising explanations. This process doesn't just describe what living things are; it explains why they work the way they do, using mechanisms that can be tested and falsified.
The Characteristics of Life
All living organisms share seven properties:
- Cellular organization — made of one or more cells
- Order — complex, organized structure
- Energy use and metabolism — transform energy; carry out chemical reactions
- Response to stimuli — react to environmental changes
- Homeostasis — maintain internal stability
- Growth and development — increase in size and complexity
- Reproduction — produce offspring
Non-living systems (fire, crystals, rivers) may exhibit some of these — none have all seven.
Science Vocabulary
Observation: direct measurement or description using the senses or instruments.
Example: "The frog's heart rate increased from 40 to 52 beats/min when temperature rose from 10°C to 20°C."
Inference: a logical conclusion drawn from observations.
Example: "Higher temperature may increase metabolic rate in ectotherms."
Hypothesis: a testable, falsifiable prediction derived from an observation.
Example: "If temperature increases, then frog heart rate will increase proportionally."
Theory: a well-supported explanation that integrates multiple lines of evidence and makes testable predictions. NOT a guess. Cell theory, evolution, germ theory — these are as certain as scientific knowledge gets.
Law: a description of a consistent, universal pattern (e.g., the law of conservation of mass). Laws describe; theories explain.
Example 1 — Observation vs. Inference
| Statement | Type |
|---|---|
| "The bacteria colony turned yellow when antibiotic A was added." |