Biology 1020 Chapter 1 Notes: Themes in Biology

What is Biology?

  • Biology is the scientific study of life.

What is Science?

  • Science is a way of knowing about the natural world.
  • Latin roots: science = knowledge.

What is Life?

  • Life is a broad, diverse phenomenon that can include humans, pets, plants, and even microscopic forms.
  • Life raises questions such as: What was life in the past? What constitutes life beyond current organisms (extinction, life on other planets, etc.)

Seven Features of Living Organisms

  1. Life is ordered & organized.
    • Organisms have structure and organization that meet ecological needs.
  2. Life responds to its environment.
    • The physical environment changes; living things respond to changes in their surroundings.
  3. Life reproduces itself.
    • Reproduction creates new organisms and maintains populations.
  4. Life regulates itself.
    • Organisms respond to external changes and regulate internal processes.
  5. Life grows & develops.
    • Life begins as a single cell and divides/grows to build more complex structures.
  6. Energy processing.
    • Chemical energy (via cellular respiration) is used and energy changes forms within living systems.
  7. Evolutionary adaptation.
    • Life is ancient; living things show evidence of changes that enhance survival and reproduction.

Additional Characteristic Details about Life

  • Life requires water.
  • Life is carbon-based.
  • Life is made of cells.
  • Life uses DNA to encode information.
  • Life is integrated with other organisms (ecological interactions).

Hierarchy of Biological Organization (from most complex to least)

  • Biosphere (most complex; includes all life and its environments)

  • Ecosystems

  • Communities

  • Populations

  • Organisms

  • Organs & organ systems

  • Tissues

  • Cells

  • Organelles

  • Molecules

  • Atoms

  • Notes:

    • The biosphere is the outermost, largest system and is integrally connected to the atmosphere, hydrosphere, and lithosphere.
    • A single cell can be an organism (unicellular life).
    • Cells are the fundamental units of life, with organelles carrying out essential functions.
    • Organelles are composed of molecules, which are composed of atoms.

Biological Classification and Taxonomy

  • Living organisms can be classified into named groups (taxa) within a nested hierarchy.
  • Taxa are ordered as: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
  • Rules for naming:
    • Domain, Kingdom, Phylum, Class, Order, Family have capitalized names; genus is capitalized; species is not.
    • Genus and species are written in italics (e.g., Homo sapiens).
    • For species names, the genus can be abbreviated to a single letter after the first use (e.g., H. sapiens).
  • Taxonomy reflects evolutionary history (phylogeny) and relationships among organisms.

The Three Domains of Life and Protists

  • Three Domains:
    1) Archaea
    2) Bacteria
    3) Eukarya (everything else: animals, plants, fungi, etc.)
  • Protists are not animals, plants, or fungi; they are a heterogeneous group within Eukarya.

Viruses: Are They Alive?

  • Viruses contain nucleic acid and can carry genetic information but cannot reproduce independently.
  • They are not cells and do not carry out life processes on their own; they require host cells to replicate.
  • Therefore, viruses occupy a gray area: not fully alive by traditional cellular criteria, but integrate with life through infection and replication cycles.

What is Science? (Continued)

  • Science is a Latin term meaning knowledge.
  • It is a method for understanding natural phenomena through observation and testing of hypotheses.

The Scientific Method (5 steps)

  1. Making observations
    • Observations should be as unbiased and accurate as possible to inform hypotheses.
  2. Forming & Testing Hypotheses
    • A hypothesis is a testable question or educated guess that can be evaluated by experiments.
  3. Controlled Experiments
    • Experiments are designed to test hypotheses with controlled variables.
  4. Data collection
    • Data are gathered from experiments to assess outcomes.
  5. Conclusions
    • Findings summarize results and determine whether the hypothesis was supported.

Theories in Science (Examples)

  • Evolutionary Theory
  • Atomic Theory
  • Plate Tectonic Theory
  • Big Bang Theory
  • Cell Theory
  • Germ Theory
  • Theory of Gravity
  • Theories of Relativity

What is a Theory?

  • A scientific theory is a broad framework or model for explaining natural phenomena.
  • It generates more specific, testable hypotheses.
  • It must be supported by observational and experimental evidence to be accepted.
  • It will be modified in light of new scientific data.
  • It is not a wild guess.
  • Science is not perfect and theories can be refined over time.

Connections to Foundational Principles and Real-World Relevance

  • Understanding hierarchical organization helps explain how changes at the molecular level affect organisms and ecosystems.
  • Taxonomy and phylogeny illustrate evolutionary relationships used in medicine, agriculture, and conservation.
  • The concept of energy processing links to metabolism, nutrition, and disease.
  • The scientific method underpins evidence-based decision making in healthcare, environmental policy, and technology.
  • The status of viruses as non-cellular replicators informs vaccine development, virology, and public health strategies.

Practical Implications and Ethical Considerations (Brief)

  • Scientific theories guide policy and ethical discussions (e.g., genetic technologies, conservation strategies).
  • Absolute certainty is rare in science; decisions often rely on the best available evidence with acknowledgment of uncertainty.
  • Responsible science requires transparency, reproducibility, and consideration of societal impact.

Summary of Key Takeaways

  • Biology is the scientific study of life, emphasizing organization, metabolism, growth, reproduction, response, regulation, evolution, and energy processing.
  • Life exists within a hierarchical organization from atoms to the biosphere and is interconnected through ecosystems and ecological networks.
  • Taxonomy classifies life into a nested hierarchy reflecting evolutionary history, organized into three domains with domain-specific features.
  • Viruses challenge traditional definitions of life and highlight the spectrum of biological organization.
  • Science advances through observations, hypotheses, controlled experiments, data collection, and conclusions, building robust theories.
  • Theories summarize broad, evidence-based explanations and guide future research and application, while remaining open to revision as new data emerge.