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Introduction to Life Science

Why a Study of Biology is Important?
 Societal
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Medicine
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Public Health
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Worldwide Water Crisis
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Why a Study of Biology is Important?
 Philosophical
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Evolution
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Genetics
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Why a Study of Biology is Important?
– Personal
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To be informed
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Support your cause
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Make it your life work
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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[bahy-ol-uh-jee]
 Bio = life
 ...ology = the study of
 Biology is the science that studies life
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The Scientific Method in Action
 A systematic way of gaining information
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The Scientific Method: Observation
 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?
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The Scientific Method:
The Hypothesis
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 Hypothesizing
– question an observation
– propose possible solutions to questions based on what is already understood about the phenomenon
 Hypotheses must:
– be logical
– account for all current information
– make the least possible assumptions
– be testable
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Testing Hypotheses
 Hypotheses need to be tested to see if they are supported or disproved.
– Disproved hypotheses are rejected
– Hypotheses can be supported but not proven
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 Ways to test a hypothesis:
– Gathering relevant historical information
 Retrospective Studies
– Make additional observations from the natural world
– Experimentation
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The Scientific Method:
Experimentation
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 Experiments
– rigorous tests to determine if the solutions are supported
 Experiments attempt to recreation an occurrence
– tests whether or not the hypothesis can be supported or rejected
 There are many types of experiments
– laboratory, clinical trials, surveys, statistical analyses
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Experimental Design
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 All experiments have key elements in common:
– Experiments must be controlled
 this means that all aspects except for one variable must be kept constant
 usually include any two groups.
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Experimental group: variable is altered, independent variable
Control group: variable is not altered, dependent variable
– Experiments use models to recreate occurrences, but in a controlled setting
 model organisms , ISS , cohorts
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Experimental Design
 Experiments must:
– use large numbers of subjects and/or must be repeated several times (replication)
– be independently reproducible
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 The validity of experimental results must:
– be tested statistically
 chi-squared test for statistical significance
– be scrutinized by other scientists
 peer reviewed
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Theory
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If the hypothesis is supported by ample experimental data, it leads to a theory.
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.
 Many diseases are not caused by microorganisms, so we must be careful not to generalize theories too broadly.
Theories continue to be tested
 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.
– An example: All living things come from pre-existing living things.
 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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Deductive reasoning
We can predict that a newly discovered bird species will lay eggs.
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Scientific Communication
 Data is shared with the scientific community through research articles published in scientific journals.
– peer review
 Scientists present preliminary data at conferences.
 Scientists collaborate directly by phone and e-mail .
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A Sample Experiment
Scientific American August 2010
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A Sample Experiment
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Article: Hardt, Marah J. and Safina, Carl. “Threatening Ocean Life from the Inside Out.” Scientific American August 2010: Vol. 303 2.
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What types of observations were being made?
State a hypothesis that was tested.
Describe an experiment that was conducted.
Discuss a variable that was studied and describe how constants where maintained in the experiment.
How was a model system was used to simulate the conditions being studied.
How were the complex processes being studied reduced to their simplest parts?
What was learned from the experiments?
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