Biology / Unit 1: The Science of Biology and Chemistry of Life
1.2 The Scientific Method
Notes
Science answers questions with evidence from observations and experiments.
- A hypothesis is a testable explanation, often written as an if-then statement.
- The independent variable is what the scientist changes on purpose.
- The dependent variable is what is measured as a result.
- Controlled variables (constants) are kept the same in every group.
- The control group gets no treatment or normal conditions, for comparison.
- Repeating trials and using large samples makes results more reliable.
- A theory is a well-tested explanation supported by lots of evidence, not just a guess.
Practice
A student gives plants 0, 10, 20, and 30 mL of fertilizer and measures their height after 3 weeks. What is the dependent variable?
The dependent variable is what is measured in response to the change.
In that same experiment, which group is the control group?
The control group gets no treatment, so the others can be compared to it.
Which statement best describes a scientific theory?
Theories, like cell theory, are well supported but can be refined by new evidence.
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