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Biol 178Principles of Biology

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Chapter Organization

Lecture Outline

Definition of Life Properties of Life Hierarchical Organization Unifying Themes of Science Scientific Method

What is Biology?

o Study of life

o Search for order in the natural world

o Discovery of new relationships

o Learn working rules that allow life to exist

Properties of Life

Cellular organizationOrderSensitivityGrowth, development, and reproductionGenetic system DNAEnergy utilizationEvolutionary adaptationHomeostasis

Hierarchical Organization of Life

1.Population Level

2.Organism Level

3.Cell Level

LifeLevels of OrganizationPopulations…Among

Organisms

1.Biosphere

2.Ecosystem

3.Community

4.Population

LifeLevels of Organization

Within Organisms

1.Organ systems

2.Organs

3.Tissues

4.Cells

LifeLevels of Organization

Within Cells

1.Organelles

2.Macromolecules

3.Molecules & Atoms

LifeLevels of Organization

1.Among organisms

2.Within Organisms

3.Within Cells

Consequences of Hierarchical organization

• Emergent properties

• New properties arise at each higher level

• Make life difficult to define

Unifying Themes of Science

1. Cell theoryAll living organisms are made of cells, and all living

cells come from other living cells.

2. Molecular basis of inheritanceDNA encodes genes

Genes make-up & control living organisms.

Unifying Themes of Science

3. Evolutionary changeLife-forms have evolved varying characteristics to adapt to

varied environments.

4. Evolutionary conservationSome characteristics of earlier organisms are preserved and

passed on to future generations.

Summary: Unifying Themes of Science

1. Cell theory

2. Molecular basis of inheritance

3. Evolutionary change

4. Evolutionary conservation

Scientific Inquiry – How is Science Done?

Discovery ScienceObserving

Measuring

Hypothesis-based ScienceScientific Method

Proposing & Testing hypotheses

Inductive & deductive logic

Reasoning

Deductive reasoningApply general principles to predict specific results

Inductive reasoningUse specific observations to construct general

principles

How Science Is Done

1. Observation: Begins science

2. Hypothesis: accounts for observationsEducated guess

Inductive Reasoning Generalization

3. Prediction: Allows test of hypothesis validityDeductive Reasoning specific outcome

4. Experiment: Tests hypothesis validity

5. Controlled experiment:One variableControl

How Science Is Done

Limitations of Science

Hypothesis can NOT be proven true

Truth Table

Hypothesis Prediction

True True

False False or True

Limitations of Science

Science does not prove hypotheses are true.

Science proves that some hypotheses are not true.

Hypotheses not proven false are conditionally accepted.

Hypotheses, Theories & Laws

Hypothesis a tentative explanation.

Scientific TheoryAccepted explanation.Supported by experimental evidence.Solid ground of science.A well-supported hypothesis.

Scientific LawScientific knowledge accepted as true.An extremely well-supported hypothesis.

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