Biology Chapter 1: The Science of Biology

Chapter 1: The Science of Biology

• Biology is the study of living things.
• Living things are diverse and grouped into kingdoms based on similar characteristics.
• Members of different kingdoms are typically very different.
• The book is titled "Essentials of the Living World" Seventh Edition, by George Johnson and Joel Bergh.

Properties of Life

• Living things exhibit complexity, movement, and respond to stimuli.
• These properties are exclusive to living things.
• Key properties of life include:
  • Cellular organization (all living things composed of one or more cells).
  • Metabolism (all living things process energy to power other processes).
  • Homeostasis (living things maintain a stable internal environment for optimal metabolic function).
  • Growth and reproduction (all organisms grow and reproduce).
  • Heredity (passing of genetic information from parents to offspring).

Levels of Organization

• Living things interact at multiple levels of increasing complexity.
• Levels include cellular, organismal, and populational.
• The organization of life is a hierarchy of levels.

Emergent Properties

• At higher levels of the biological hierarchy, new properties arise that weren't present at lower levels.
• These new properties result from interactions of diverse, simpler components.
• Examples of emergent properties include metabolism and consciousness.

Biological Themes

• The study of life is based on general themes.
• Five recurring biological themes:
  • Evolution (genetic change in species over time) with natural selection as the mechanism
  • Flow of Energy (energy from the sun flows through the environment; organisms acquire energy in different ways).
  • Cooperation (organisms often cooperate for survival, with symbiosis as a type of cooperation).
  • Structure Determines Function (evolution favors structures that function in adaptive ways, many structures are specialized, and structure-function convergence occurs across the biological hierarchy).
  • Homeostasis (a condition of "steady-state" where internal environments are relatively stable, with organisms controlling their internal environments for metabolism function).

The Scientific Process

• Biology is a dynamic science where new ideas replace old ones.
• Scientists systematically conduct experiments to evaluate hypotheses about phenomena.
• Key steps of the scientific process:
  • Observation
  • Hypothesis (educated guess, often multiple alternative hypotheses possible).
  • Predictions (outcomes if the hypothesis was correct).
  • Testing (experiments to verify predictions).
  • Controls (experiments usually employ parallel design, using controls to assess influence of variables; control conditions remain constant relative to variable conditions).
  • Conclusion (hypotheses tested and not rejected are tentatively accepted).

Theory and Certainty

• The term "theory" has different meanings for scientists vs. the public.
• To scientists, a theory represents a certainty and unifying explanation of observations.
• To the public, a theory might represent a guess or lack of knowledge.

Unifying Biological Theories

• Four theories that unify biology as a science:
  • Cell theory (all organisms made of one or more cells)
  • Gene theory (genetic information encoded in DNA, genes encode proteins).
  • Heredity theory (genes are passed down generation- to-generation as discrete units, with Mendel's theory giving rise to genetics; inheritance is located on chromosomes).
  • Evolution theory (all organisms related in a common tree of descent, grouped into three domains, with evolution explaining unity and diversity of life. Natural selection is the mechanism behind evolution.)