Nature of Science

What is science?

• Controlled Experiment: An experiment where only one variable is changed at a time to clearly understand the results.  

  • Parts of a Controlled Experiment:

    • Controls: What stays the same in the experiment.  

    • Independent Variable: What is being changed by the experimenter.  

    • Dependent Variable: What is being measured as a result of the change.  

  • Examples:

    • Strep throat medicine:

      • Independent Variable: The type of medication (new vs. traditional).  

      • Dependent Variable: Effectiveness of the medicine (e.g., patient recovery).  

      • Controls: Other factors like patient age, severity of illness, diet, etc..  

    • Algebra teaching method:

      • Independent Variable: The teaching method (new vs. old).  

      • Dependent Variable: Standardized test scores.  

      • Controls: Teacher experience, student prior knowledge, class size, etc..  

The Scientific Method

• The scientific method is a process for gathering and using information, starting with observations.  

• Steps:

  1. State the Problem or Question: Based on observations.  

  2. Gather Information (Research).  

  3. Form a Hypothesis: A testable explanation or guess based on existing knowledge.  

     • Inductive Reasoning: Forming a general rule or pattern from many specific observations (e.g., all birds have feathers).  

     • Deductive Reasoning: Applying a general rule to a specific situation (e.g., if all birds have feathers and this has feathers, it must be a bird).  

  4. Test the Hypothesis: By conducting an experiment.  

  5. Collect & Analyze Data: Information collected from an experiment, organized into charts, graphs, or tables for readability.  

     • Qualitative Data: Descriptions using words (e.g., leaves are green, plant looks healthy).  

     • Quantitative Data: Numbers or measurements (e.g., average leaf diameter is 3 cm, height of plant is 29 cm).  

     • Graphing Data: Independent variable on the X-axis, dependent variable on the Y-axis.  

  6. Draw Conclusions: Either supports or rejects the hypothesis.  

     • Science does not prove something is TRUE, but can disprove it or be fairly certain a hypothesis is correct.  

     • Repeating the experiment increases confidence in the results.  

  7. Share Information: Report findings to others.  

Scientific Community and Ethics

• Peer Review: Scientists submit results to peers (individuals at the same level of education/specialization) who review the experiment for flaws. If satisfied, results may be published in a scientific journal. It's crucial for guarding against faulty science.  

• Scientific Theory: Explains a phenomenon and is supported by much evidence from various fields. They are broad explanations that apply to many situations (e.g., atomic theory, cell theory, evolution, plate tectonics).  

  • Theory vs. Law: A scientific theory is a hypothesis tested with significant data. A scientific law describes a pattern in nature, generally without explaining "why" (e.g., every action has an equal and opposite reaction).  

• Ethics in Science: Scientists must consider moral principles in every experiment.  

  • Ethical Worldviews:

    • Anthropocentrism: Values human populations and welfare most.  

    • Biocentrism: Values each and every organism, including humans.  

    • Ecocentrism: Values the entire ecosystem or community rather than individuals.  

What is Life?

• Biology is the study of living things.  

• Spontaneous Generation: The old belief that life arose from nonliving things (e.g., maggots from meat).  

  • Francesco Redi's Experiment (1668): Showed flies laid eggs on meat, which then hatched into maggots; they did not spontaneously arise from the meat.  

  • Louis Pasteur's Experiment: Designed an experiment with swan-necked flasks to show that microorganisms only grew in broth when exposed to pre-existing microorganisms, further disproving spontaneous generation.  

• Biogenesis: The theory that living things come from other living things.  

• Eight Characteristics of All Living Things: To be considered "living," an entity must exhibit ALL of these characteristics.  

  1. Made of Cells: Tiny, organized units that grow, divide, and respond to their environment.  

  2. Reproduce: Either sexually (two parents) or asexually (one parent).  

  3. Have a Universal Genetic Code: DNA carries the blueprint for an organism's characteristics.  

  4. Grow: Can get larger or undergo elaborate developmental processes.  

  5. Require Energy: Obtained from the sun, chemicals, or by consuming other organisms.  

  6. Respond to Their Environments: React to changes to stay alive.  

  7. Maintain Internal Balance (Homeostasis): Maintaining stable internal conditions despite external changes (e.g., sweating to cool down).  

  8. Change Over Time (Evolution): Groups of organisms adapt to their environment through changes over time.