Biology 101 Chapter 1

The Scientific Study of Life


Biology = the study of living things and their interactions.

              Bio – life

              logy – study of


1.1       Life’s Levels of Organization





                            Organ Systems






*This order represent life’s hierarchy of complexity


1.2 The Scientific Method

- Investigative process of studying the natural world


1)    Observations: objective, quantitative, many forms

2)    Questions

3)    Hypotheses: tentative explanations that attempt to answer the questions

4)    Predictions: deductive reasoning to predict the results if hypothesis is correct, “If…..then” logic

5)    Tests: experimentation

6)    Revision: either accept present hypothesis or revise it.  Re-test


The scientific process also is:

·      a cyclic process

·      involves critical thinking at every step

·      is cumulative

·      can support or falsify a hypothesis


A word on “Hypothesis”!

·      Must be testable

·      Must be falsifiable

·      And is never proven absolutely true


What is a Theory?

       A hypothesis that has survived rigorous testing, is widely accepted, has a broad scope, and is supported by a large body of evidence.

       Ex. Theory of Evolution


What is a Law?

       A widely accepted principle that makes predictions but has no explanatory power.

       Ex. Laws of Thermodynamics

1.4 Evolution, Unity and Diversity

Some features of living organisms are determined by ENVIRONMENT.

Others are determined by HEREDITY.


Life is very diverse = >2 million species

       Ex. plasmodium slime mold – grizzly bear


How many students in this class have heard of the French Impressionist painter Monet?  Art students who are familiar with Monet’s work can probably pick out a Monet painting from a gallery of different paintings,  because of the unity of theme and style in his work.  Each Monet painting is unique in its subject and effect, in other words, there is a tremendous diversity in his paintings.   Yet there is also a stylistic unity.  In Monet’s work, there is unity in the midst of diversity.


Life is unified in a hierarchical classification










3     Domains:

1)    Archaea

2)    Bacteria

3)    Eukarya


5     Major Kingdoms

1)    Monera = bacteria

2)    Protista = algae and protozoans

3)    Fungi = molds, yeast, mushrooms

4)    Plantae = plants

5)    Animalia = animals


What is life?  What distinguishes life from non-life?  What unifies life?

1.5 Characteristics of Life

1.    Order

2.    Regulation

3.    Growth and Development

4.    Energy Utilization

5.    Responsiveness

6.    Reproduction


1.6 Evolution as a Unifying Theme of Life

-        evolution explains the unity of life

-        Evolution = genetic (heritable) changes in a population or species over generations.  All life is evolving.

-        Charles Darwin:

·      born in 1809

·      in 1831 began a round-the-world voyage at age 22 on board the H.M.S. Beagle as a naturalist

·      1859 published “On the Origin of Species”

·      proposed a mechanism for evolution


-        Evolution vs. Spontaneous Generation


MACROEVOLUTION = big changes, accumulated from small changes over long periods of time

MICROEVOLUTION = small changes in the relative frequencies of traits (color) in a population


Theory of Evolution: Two parts

1)    Natural Selection = differential, or unequal, success in reproduction.  (compare to artificial)

2)    Adaptation = share a common ancestor, that is species arise as the result of descent with modification.


·      Assumptions it is based upon:

1. variation within a population

2. heritable traits

3. overproduction of offspring

4. selection pressures (limited natural resources)

5. struggle to survive

6. preferential reproduction

7. small changes over geologic time

What is a species?


Biological Species Definition!!!

       A population or group of populations whose members have the potential to interbreed and produce fertile offspring.


Evolutionary Species Concept:

       A species represents a cluster of organisms that share a geneology, or lineage of descent.


Origins of Life: Early Chemical and Biological Evolution