Chapter 1
Lecture Outline
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Why a Study of Biology Is
Important
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To be an informed citizen
An understanding of biology is important to
address a number of social issues today.
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DNA testing
Birth control
Global warming
AIDS
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So Then, What Is Biology?
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Biology is the science that deals with life.
What is science?
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A process used to solve problems and understand
natural events
Involves the scientific method
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Basic Assumptions in Science
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Scientists approach their work with some basic
assumptions:
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Natural events have specific causes.
The causes for events in nature can be identified.
Natural events follow general rules and patterns.
A recurrent natural event has a common cause.
Different people can observe the same natural events.
Natural laws hold true regardless of time and place.
Example: Lightning
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Scientists Look for Cause and Effect
Relationships
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Events that happen simultaneously are
correlated, but
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Events have a cause and effect relationship
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may or may not have a cause and effect
relationship.
Example: Autumn and falling leaves
when one event happens as a direct result of a
preceding event.
Example: Lightning causes thunder.
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The Scientific Method
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A way of gaining information about the world
that involves
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forming possible solutions to questions.
rigorous testing to determine if the solutions are
supported.
continual checking and rechecking to make sure
that previous conclusions are still supported.
modification of unsupported conclusions.
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Components of the Scientific Method
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Observation
Questioning and exploration
Forming and testing hypotheses
Evaluation of new information
Review by peers
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The Scientific Method in Action
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Observation, Questioning, and
Exploration
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An observation is a thoughtful and
careful recognition of an event or a fact.
The careful observation of a
phenomenon leads to a question.
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How does this happen?
What causes it to occur?
The question must be testable.
Scientists then explore scientific
publications to find any information that
has been gathered about the question.
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Constructing Hypotheses
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Once the question is asked, scientists
propose answers.
These answers are hypotheses.
Hypotheses must:
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be logical.
account for all current information.
be testable.
make the least possible assumptions.
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Testing Hypotheses
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Hypotheses need to be tested to see if they
are supported or disproved.
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There are several ways to test a hypothesis:
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Disproved hypotheses are rejected.
Hypotheses can be supported but not proven.
Gathering relevant historical information
Make additional observations from the natural
world.
Experimentation
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Experimentation
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An experiment is a re-creation of an
occurrence.
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It tests whether or not the hypothesis can be
supported or rejected.
Experiments must be controlled.
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This means that all aspects except for one
variable must be kept constant.
They usually include any two groups.
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Experimental group: variable is altered
Control group: variable is not altered
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Experimental Design
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The variable that is altered is called the independent
variable.
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The variables that change in response to the
independent variable are called dependent variables.
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Experiments should have only one independent variable.
Changes in the dependent variables are documented as
data.
Data from the experiment is analyzed and
hypotheses are rejected and revised or supported.
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A Sample Experiment
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Hypothesis: Male sex hormones produced by the testes
stimulate male birds to sing.
Experimental group: Male birds with testes removed at birth.
Control group: Male birds subjected to a similar surgery that
were allowed to develop normally with testes.
Independent variable: Presence or absence of testes.
Dependent variable: Presence of singing behavior.
Data: Male songbirds without testes do not exhibit singing
behavior.
Conclusion: Hypothesis is supported.
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Experimental Data
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Experiments must:
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The validity of experimental results must:
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use large numbers of subjects or must be
repeated several times (replication).
be independently reproducible.
be tested statistically.
be scrutinized by other scientists.
If the hypothesis is supported by ample
experimental data, it leads to a theory.
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Theory
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A theory may be defined as a widely accepted,
plausible general statement about a
fundamental concept in science.
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The germ theory states that infectious diseases are
caused by microorganisms.
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Theories continue to be tested.
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Many diseases are not caused by microorganisms, so we
must be careful not to generalize theories too broadly.
Exceptions identified
Modifications made
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A Scientific Law
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A scientific law is a uniform and constant fact of nature
that describes what happens in nature.
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Scientific laws promote the process of generalization.
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Inductive reasoning
Since every bird that has been studied lays eggs, we can generalize
that all birds lay eggs.
Once a theory becomes established, it can be used to
predict specific facts.
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An example: All living things come from pre-existing living things.
Deductive reasoning
We can predict that a newly discovered bird species will lay eggs.
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Scientific Communication
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Data is shared with the
scientific community through
research articles published
in scientific journals.
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These articles are usually
scrutinized by other
scientists before they are
published.
Scientists present
preliminary data at
conferences.
Scientists collaborate
directly by phone and
e-mail.
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Fundamental Attitudes in Science
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Scientists must distinguish between opinions and
scientific facts.
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A good scientist must
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Scientists’ opinions may become facts if supported by data.
be skeptical.
not be biased.
be honest in analyzing and reporting data.
The critical difference between science and nonscience is that in science, one can test the
principle. In non-science, one may not be able to.
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Theoretical vs. Applied Science
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Initially, some scientific data
seems to be purely
informational and not very
practical.
Practical applications
usually follow the
discoveries of basic science.
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The discovery of the structure
of DNA has led to new drug
treatments for many diseases.
The discovery of
microorganisms has led to a
dramatic decrease in infectious
disease and food preservation.
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Science vs. Nonscience
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Scientists continually challenge and test
principles to determine cause-and-effect
relationships.
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Nonscientists cannot test their hypotheses
directly and often cannot establish causeand-effect relationships.
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Biology, Physics, Chemistry, Astronomy
History, Literature, Philosophy, Art, Sociology, etc.
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Pseudoscience
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A deceptive practice
that uses the language
of science to convince
people into thinking that
a claim has scientific
validity.
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Marketing claims of
nutritional supplements
Marketing claims of
organic foods
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Limitations of Science
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The scientific method can only
be applied to questions that have
a factual base.
Questions of morality, values,
social issues, and attitudes
cannot be tested scientifically.
Science is limited by scientists.
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But, science is self-correcting.
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People are fallible.
The sun orbits the earth.
New data shapes new
hypotheses.
The earth rotates on its axis, so
maybe the earth orbits the sun.
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The Science of Biology
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Biology is the study of living things.
Theoretical biology
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Applied biology
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Evolutionary biology, animal behavior,
biochemistry
Medicine, crop science, plant breeding, wildlife
management
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What Makes Something Alive?
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Living things can manipulate energy and
matter.
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Characteristics of Living Things
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Metabolic processes
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Generative processes
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Organisms gain and store energy in the
chemical bonds in the nutrients they take in.
Organisms grow by increasing the number
of cells.
Organisms reproduce either sexually or
asexually.
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Characteristics of Living Things
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Responsive processes
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Organisms react to changes in their
environment.
 Irritability:
the ability to recognize that
something in its surroundings has changed (a
stimulus) and respond to it quickly.
 Individual adaptation: a longer term response
to an environmental change.
 Evolution: changes in a population over time.
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Characteristics of Living Things
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Control processes
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Enable organisms to carry out metabolic
processes in the right order.
 Coordination:
Enzymes coordinate metabolic
reactions.
 Regulation: Enzymes are regulated in order to
maintain homeostasis.
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Unique structural organization
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Organisms are made of cells.
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Levels of Biological Organization and
Emerging Properties
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Biosphere—the worldwide ecosystem.
Ecosystem—communities that interact
with one another in a particular place.
Communities—populations of different
organisms interacting with each other
in a particular place.
Population—a group of individual
organisms in a particular place.
Organism—an independent living unit.
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Levels of Biological Organization
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Organ system—many organs that perform a particular
function.
Organ—many tissues that perform a particular function.
Tissue—many cells that perform a particular function.
Cell—simplest unit that shows characteristics of life.
Molecules—specific arrangements of atoms.
Atoms—the fundamental units of matter.
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The Significance of Biology in Our
Lives
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Biology has significantly contributed to our
high standard of living.
For example:
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Advanced food production
Significant progress in health
Advances in disease control
Advances in plant and animal breeding
Advances in biotechnology
Progress in genome studies
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Biological Research Improves Food
Production
One food that has seen a vast increase in
production and variation is the tomato.
Tomatoes (Lycopersicon sp.) originated on the
western coast of South America in Peru. Wild
tomato species have tiny fruits, and only the
red ones are edible. Over the centuries,
selective breeding and biotechnology have
resulted in the generation of hundreds of
varieties of this vegetable.
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