Chapter 1: Introduction – Evolution and the Foundations of Biology (Campbell Biology in Focus, 3rd Edition)

Overview: Inquiring About Life

• Biology is the scientific study of life and how living organisms function and interact.

Themes in the Study of Life

Unifying Themes in Biology

• Organization: Life is structured in a hierarchy from molecules to the biosphere.

• Information: Genetic information is stored, transmitted, and expressed in living systems.

• Evolution: Evolution explains both the unity and diversity of life.

Levels of Biological Organization

Life can be studied at various levels, from molecules to the entire biosphere. Each level reveals emergent properties not present at lower levels.

• Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

Each higher level displays emergent properties not found at lower levels.

Level	Definition
Atom	Smallest unit of matter
Molecule	Two or more atoms are bonded
Organelle	Specialized structure inside cells
Cell	Basic unit of life
Tissue	Group of similar cells
Organ	Structure made of tissues
Organ System	A group of organs working together
Organism	Individual living thing
Population	Same species in one area
Community	All populations in one area
Ecosystem	Living and nonliving things are interacting
Biosphere	All ecosystems on Earth

Emergent Properties

Emergent properties

As biological organization increases, new properties emerge that are not present at lower levels.

Example:

• Molecules are not alive

• Cells ARE alive

KEY IDEA:

The whole is greater than the sum of its parts.

Theme 1: New Properties Emerge at Successive Levels of Biological Organization

Biological Hierarchy

Life can be studied at different levels, from molecules to the entire planet. Each level reveals emergent properties not present at lower levels.

• Structure and Function: There is a correlation between structure and function at every level of biological organization. Analyzing structure provides clues to function.

The Cell: The Basic Unit of Life

The cell is the smallest unit of life capable of performing all life functions. There are two main types of cells:

• Prokaryotic cells: Lack a nucleus and membrane-bound organelles; generally smaller (e.g., Bacteria, Archaea).

• Eukaryotic cells: Contain a nucleus and membrane-bound organelles; found in plants, animals, fungi, and protists.

Prokaryotic vs Eukaryotic Cells

Feature	Prokaryotic	Eukaryotic
Nucleus	No	Yes
Membrane-bound organelles	No	Yes
Size	Smaller	Larger
Examples	Bacteria, Archaea	Plants, animals, fungi, protists

Genetic Material and Inheritance

• DNA is the hereditary material in cells.

• Genes are segments of DNA that carry inherited information.

• DNA directs growth, development, and cell function.

The Core Theme: Evolution Accounts for the Unity and Diversity of Life

Evolution: Unity and Diversity of Life

• Evolution explains both the unity and diversity of life.

Properties of Life

• Definition of Life: Living organisms share common characteristics that distinguish them from nonliving things.

  Summary Table:

Properties of Life Property	Description
Organization/Order	complex but ordered structure; composed of cells
Homeostasis	Maintaining stable internal conditions
Metabolism	Obtaining and using energy; expelling waste
Reproduction	Producing new offspring (sexual or asexual)
Growth and Development	Genes control the pattern of growth
Response to Stimuli	Sensing and responding to the environment
Evolution	Populations change over generations through natural selection

Classification of Life

Life is classified into three domains:

• Bacteria (prokaryotes)

• Archaea (prokaryotes)

• Eukarya (eukaryotes: Plantae, Fungi, Animalia, and Protists)

Classification of Life

• Three Domains: Bacteria, Archaea (both prokaryotic), and Eukarya (eukaryotic).

• Domain Eukarya: Includes Plantae, Fungi, Animalia, and Protists.

Four Major Kingdoms

Kingdom	Main Traits
Plantae	Photosynthetic, cell walls
Fungi	Absorb nutrients, chitin cell walls
Animalia	Consumers, no cell walls
Protists	Diverse eukaryotes, mostly unicellular

Charles Darwin and the Theory of Natural Selection

• Individuals vary in traits

• Traits are inherited

• More offspring are produced than survive

• Better-adapted organisms reproduce more

• Advantageous traits become more common over generations

• Natural selection is the mechanism of evolution.

The Process of Science

Scientific Inquiry and Hypotheses

Science is a process of inquiry involving observation, hypothesis formation, and experimental testing. Hypotheses must be testable and falsifiable.

• Qualitative Data: Descriptive observations.

• Quantitative Data: Numerical measurements, often displayed in tables or graphs.

• Inductive Reasoning: Drawing generalizations from many observations.

• Deductive Reasoning: Making specific predictions from general premises.

Hypothesis vs Theory

Hypothesis	Theory
Testable explanation	Broad explanation supported by evidence
Narrow scope	Broad scope
Can be disproven	Generates new hypotheses

Experimental Design

• Experiments test hypotheses by manipulating variables and comparing experimental and control groups.

Term	Definition
Independent Variable	Factor changed by the researcher
Dependent Variable	Measured outcome
Control Group	Normal comparison group
Experimental Group	Receives treatment

Example of a Controlled Experiment

Question: Does fertilizer increase plant growth?

• Independent variable = amount of fertilizer

• Dependent variable = plant height

• Control group = plants without fertilizer

• Experimental group = plants with fertilizer

Qualitative vs Quantitative Data

Qualitative	Quantitative
Descriptive	Numerical
Color, texture	Height, mass

The Scientific Method

1. Make an observation

2. Ask a question

3. Study previous research

4. Form a hypothesis

5. Test the hypothesis with experiments

6. Analyze results

7. Conclude and repeat as necessary

Results must be reproducible by other scientists.

Science vs Other Ways of Knowing

Science:

• Based on evidence

• Testable

• Repeatable

• Peer-reviewed

• Changes with new evidence