Transcript Chapter 1 What is Biology

PowerPoint to accompany
CONCEPTS IN BIOLOGY
TWELFTH EDITION
Enger • Ross • Bailey
CHAPTER 1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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1.1 The Significance of Biology in Your Life
Consider how your future will be influenced by how
the following questions are ultimately answered：
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Dose electromagnetic radiation from electric power lines, computer
monitors, cell phones, and microwave ovens affect living things ?
Is DNA testing reliable enough to be admitted as evidence in court cases ?
Is there a pill that can be used to control a person’s weight ?
Can physicians and scientists manipulate our genes in order to control
certain disease conditions we have inherited ?
Will the thinning of the ozone layer of the upper atmosphere result in
increased incidence of skin cancer ?
Will a vaccine for AIDS be developed in the next 10 years ?
Will new, inexpensive, socially acceptable methods of birth control be
developed that can slow world population growth ?
Are human activities really causing the world to get warmer ?
How dose extinction of a species change the ecological situation where it
once lived ?
1.2 Why study biology?
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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Example 1：
Human population should be slowed.
Killing infants and forced sterilization.
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Example 2：
Mad Cow Disease.
It is important to recognize that science has a
role to play but that is does not have the
answers to all our problems. (Social and
Philosophical Questions)
So then, what is biology?
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.
Basic assumptions in science
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Scientists approach their work with some
basic assumptions
– Natural events have specific causes.
– Those causes 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
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.
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.
Components of the scientific method
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Observation
Questioning and exploration
Forming and testing hypotheses
Evaluation of new information
Review by peers
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.
– 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.
Constructing hypotheses
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Once the question is asked,
scientists propose answers.
These answers are hypothesis.
Hypotheses must:
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Be logical
Account for all current information
Be testable
Make the least possible assumptions
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.
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Gathering relevant historical information.
Make additional observations from the
natural world.
Experimentation
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.
– 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
Experimental design
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The variable that is altered is called the
independent variable.
 Experiments
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should have only one
independent variable.
The variables that change in response to
the independent variable are called
dependent variables.
 Changes
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in the dependent variables are
documented as data.
Data from the experiment is analyzed and
hypotheses are rejected and revised or
supported.
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.
Experimental data
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Experiments must:
– Use large numbers of subjects or must be
repeated several times (replication)
– Be independently reproducible.
The validity of experimental results must:
– Be tested statistically.
– Be scrutinized by other scientists.
If the hypothesis is supported by ample
experimental data, it leads to a theory.
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.
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Exceptions identified
Modifications made
A scientific law
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A scientific law is a uniform and constant fact of
nature that describes what happens in nature.
– An example: All living things come from preexisting living things.
Scientific laws promote the process of
generalization.
– 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.
– Deductive reasoning
– We can predict that a newly discovered bird
species will lay eggs.
Scientific communication
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Data is shared with the
scientific community
through research articles
published in scientific
journals.
– 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.
1.3 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
non-science is that in science, one can test the
principle. In non-science, one may not be able
to.
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.
(antibiotics, hormones,
enzymes)
The discovery of
microorganisms has led to a
dramatic decrease in infectious
disease and food preservation.
(vaccination against rabies,
pasteurization for the
preservation of food)
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 cause-and-effect relationships.
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Biology, Physics, Chemistry, Astronomy
History, Literature, Philosophy, Art, Sociology,
etc.
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.
Fig. 1.11 Pseudoscience- “Nine out of 10
Doctors Surveyed Recommend Brand X”
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.
– People are fallible.
– The sun orbits the earth.
But, science is self-correcting.
– New data shapes new
hypotheses.
– The earth rotates on its axis,
so maybe the earth orbits
the sun.
1.4 The science of biology
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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
What makes something alive?
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Living things can manipulate energy and
matter.
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.
Characteristics of living things
 Responsive
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processes
Organisms respond to changes in
their environment.
 Irritability:
the ability to recognize 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.
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Unique structural organization
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Coordination: Enzymes coordinate metabolic reactions.
(e.g., handling nutrients)
Regulation: Enzymes are regulated in order to maintain
homeostasis. (e.g., exercise)
Organisms are made of cells.
Each kind of organism has specific structural
characteristics
Levels of biological organization
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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.
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.
Significance of biology
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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
Biological research improves food
production
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Edward Jenner and the Control of Smallpox
Future Directions in Biology
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Control of the human population
Curing hereditary disease
Between genetic info. and such diseases
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Alzheimer’s disease
Stroke
Arthritis
Cancer
AIDS
Ecology: Climate change, pollution, human population
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