Chapter 1: Themes of Biology

Chapter 1: Themes of Biology

(Know the Difference)

• Hypothesis: A tentative answer (an educated guess or prediction) to a well-framed question. It must be testable and falsifiable.

• Theory: A well-substantiated explanation supported by a large body of evidence, broader in scope than a hypothesis. Example: The Theory of Evolution.

• Law: Describes an observed pattern in nature without attempting to explain it. Example: The Law of Independent Assortment.

• Quantitative Data: Recorded measurements (numerical).

• Qualitative Data: Descriptions rather than measurements (non-numerical).

(Be Able to Identify)

• Independent Variable: The variable that is deliberately changed in an experiment (cause). Plotted on the X-axis.

• Dependent Variable: The variable that is measured or observed in response to the independent variable (effect). Plotted on the Y-axis.

8 Themes of Biology (Understand What It Means)

1. New Properties Emerge at Each Level of Biological Organization

   • Life can be studied at different levels, from molecules to the entire biosphere.

   • Emergent Properties: New properties that arise with each step upward in the hierarchy of life.

2. Organisms Interact with Other Organisms and the Physical Environment

   • Organisms and their environment affect one another.

   • Example: Trees absorb CO₂ and release O₂; their roots contribute to soil formation.

3. Life Requires the Transfer and Transformation of Energy and Matter

   • Energy flows through ecosystems, entering as light and exiting as heat.

   • Example: Photosynthesis converts solar energy into chemical energy.

4. Structure and Function Are Correlated at All Levels of Biological Organization

   • Form fits function in biology.

   • Example: The shape of a bird’s wing allows flight.

5. The Cell Is an Organism’s Basic Unit of Structure and Function

   • Cells are the fundamental unit of life.

   • Prokaryotic Cells: No nucleus, simpler.

   • Eukaryotic Cells: Have a nucleus and membrane-bound organelles.

6. Life’s Processes Involve the Expression and Transmission of Genetic Information (DNA)

   • DNA contains genetic instructions that are inherited by offspring.

7. From Molecules to Ecosystems, Interactions Are Important in Biological Systems

   • Positive Feedback: As more product accumulates, the process speeds up (e.g., blood clotting).

   • Negative Feedback: As more product accumulates, the process slows down (e.g., ATP production regulation).

8. Evolution: The Overarching Theme of Biology

   • Explains unity and diversity of life.

   • Natural Selection: Individuals with beneficial traits are more likely to survive and reproduce.

(Know the Domains and Order of Groups)

• Taxonomy: The classification of life.

  • Three Domains of Life:

    1. Bacteria (prokaryotic)

    2. Archaea (prokaryotic)

    3. Eukarya (eukaryotic, includes plants, fungi, animals, and protists)

• Hierarchy of Classification (From Broadest to Most Specific):
  Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species