Biology and You
Section 2
Section 2: Scientific Methods
Preview
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Bellringer
Key Ideas
Beginning a Scientific Investigation
Scientific Experiments
Scientific Theories
Summary
Biology and You
Section 2
Bellringer
Imagine that all of the birds around the school are dying.
How might you investigate the problem?
Write a brief description of your investigation.
Which stages of a scientific investigation are represented in
your answer?
Biology and You
Section 2
Key Ideas
• How do scientific investigations begin?
• What are two methods scientists can use to test
hypotheses?
• What is the difference between a theory and a
hypothesis?
Biology and You
Section 2
Beginning a Scientific Investigation
• Most scientific investigations begin with observations
that lead to questions.
• _____________ is the act of noting or perceiving objects
or events using the senses.
• To answer a question, scientists first _______________
a hypothesis that leads to scientific investigation.
• A ________________ is a possible explanation that can
be tested by observation or experimentation.
Biology and You
Section 2
Visual Concept: Hypothesis
Biology and You
Section 2
Scientific Experiments
• An experiment is a procedure that is carried out under
controlled conditions to test a hypothesis.
• A controlled experiment tests one factor at a time and
uses a control group and an experimental group.
• A ___________ group is a group that serves as a
standard for comparison in an experiment.
• The experimental groups are identical to the control
group except for one factor, called a ____________.
Biology and You
Section 2
Scientific Experiments, continued
• The single factor that scientists change in an experiment
is called the ____________ ____________.
• Factors that may change in response to the independent
variable are called _____________ variables.
• Scientists analyze changes to the dependent variables in
order to understand how the independent variable
affects the system that they are studying.
Biology and You
Section 2
Visual Concept: Controlled Experiment
and Variable
Biology and You
Section 2
Visual Concept: Independent and
Dependent Variables
Biology and You
Section 2
Scientific Experiments, continued
• There are often cases in which experiments are
not possible or not _____________.
• In these cases, researchers perform
__________.
• In a study, researchers gather data about a
system by making ____________ rather than by
manipulating independent variables.
Biology and You
Section 2
Scientific Experiments, continued
• After conducting an experiment, researchers
___________ their results to learn whether the results
support their hypothesis or not.
• Scientists draw __________ that explain the results of
their experiments.
• Scientists verify their conclusions by conducting their
experiments _______ _________and by checking to
see if other scientists have found similar results.
Biology and You
Section 2
Visual Concept: Scientific Method
Biology and You
Section 2
Scientific Experiments, continued
• Every person has his or her own _________ __
_______. A particular point of view is called a _______.
• Scientists try to prevent bias from affecting their work,
but bias can still influence an experiment.
• Sources of funding, personal involvement in a product,
and other conflicts of interest can affect an experiment.
• It is wise to view all scientific claims in their context and
_______ _____________about them.
Biology and You
Section 2
Scientific Theories
• In science, a ___________ is a system of ideas that
explains many related observations and is supported by
a large body of _____________.
• The main difference between a theory and a hypothesis
is that a hypothesis is a _________, testable prediction
for a limited set of conditions and a theory is a general
explanation for a broad range of data.
• Constructing a theory often involves considering
contrasting ideas and _____________ hypotheses.
Biology and You
Section 2
Scientific Theories, continued
• If the results of a scientific experiment can be
reproduced many times, the research may help develop
a ______ ___________.
• Future research may cause a theory to be ________ or
even ___________.
• By investigating and _____________ theories, scientific
understanding grows.
Biology and You
Section 2
Summary
• Most scientific investigations begin with ____________
that lead to ____________.
• Scientists can conduct controlled experiments and
perform studies in order to _________ a hypothesis.
• The main difference between a theory and a hypothesis
is that a hypothesis is a specific, ____________
prediction for a limited set of conditions, while a theory is
a ___________ ______________for a broad range of
data.