Biology: The Scientific Method

The Scientific Method

• Observe: make an observation about the world around you
• Question: ask a question about what you've observed
• Hypothesis: propose a possible explanation for what you've observed, in the form of "If IV, then DV"
• Experiment: design an experiment to test your hypothesis, where:
  • One variable is changed (IV, or independent variable) while everything else remains the same
  • The experimental group receives the treatment, and the control group is used for comparison
  • The IV is the "cause" on the x-axis, and the DV (dependent variable) is the "effect" on the y-axis
  • Constants are factors that remain unchanged throughout the experiment
• Analysis: examine the data collected during the experiment, which can be:
  • Quantitative: numerical data
  • Qualitative: descriptive data
• Conclusion: summarize the findings, avoiding the use of "prove" or "disprove"
• Theory: an explanation supported by evidence
• Law: a statement of fact without explanation

Characteristics of Life

• COGHERES: an acronym to remember the characteristics of life:
  • C: cells (all living things are made of one or more cells)
  • O: organization (cells to tissues to organs to organ systems)
  • G: growth (DNA serves as instructions for growth and development)
  • H: homeostasis (regulating steady internal conditions)
  • E: energy (requires energy from the sun)
  • R: reproduction (species produce their own offspring)
  • E: evolution (changes in species over time)
  • S: stimuli (respond to stimuli)

The Study of Life

• Biology is the study of life.

The Scientific Method

• The scientific method involves a series of steps to answer a question or solve a problem.
• The steps are:
  • Observe: make an observation about the world.
  • Question: ask a question about what you have observed.
  • Hypothesis: make an educated guess that answers the question.
  • "If IV...then DV": write the hypothesis in a clear and concise format.
  • Experiment: design an experiment to test the hypothesis.
  • Analysis: analyze the data collected during the experiment.
  • Conclusion: draw a conclusion based on the data analysis.

Experiment Design

• In an experiment, everything is controlled except for one variable.
• The experimental group receives the treatment being tested.
• The control group is used for comparison.
• The independent variable (IV) is the condition being tested and is represented on the x-axis.
• The dependent variable (DV) is the condition being measured and is represented on the y-axis.
• A constant is a factor that remains unchanged throughout the experiment.

Data Analysis

• Quantitative data are numbers.
• Qualitative data are descriptions.

Conclusion

• Avoid using "prove" or "disprove" in your conclusion.
• A theory is an explanation with evidence.
• A law is a truth with no explanation.

Characteristics of Life

• COGHERES is an acronym that summarizes the characteristics of life:
  • C (cells): all living things are made of one or more cells.
  • O (organization): cells are organized into tissues, organs, and organ systems.
  • G (growth): DNA serves as the instructions for growth and development.
  • H (homeostasis): living things regulate their internal conditions to maintain a stable environment.
  • E (energy): living things require energy from the sun.
  • R (reproduce): species produce their own offspring.
  • E (evolve): species change over time.
  • S (stimuli): living things respond to stimuli.