Biology 101 Lab Study Guide
CHAPT 1 -
The scientific method allows the solving of problems and answering of questions.
Observations
Proposing ideas
Testing the ideas
Discarding or modifying ideas based on results
Hypothesis: proposed explanation for a set of observations
Hypotheses needs to be:
Testable – it must be possible to examine the hypothesis through observations
Falsifiable – it must be able to potentially be proven false
Both logical and creative influences are used to develop a hypothesis
A hypothesis that fails our test is rejected and considered disproven.
A hypothesis that passes is supported, but not proven.
Why not? An alternative hypothesis might be the real explanation.
The Experimental Method
Experiments are designed to collect data or information to test specific hypotheses.
Variables: factors that can change in value under different conditions
Independent variables can be manipulated by the scientist
Dependent variables cannot be changed by the researcher
Controlled experiment: tests the effect of a single variable
Control: a subject who is not exposed to the experimental treatment but has all other variables the same
Controlled Experiments
Differences seen between the experimental group and control group can be attributed to the experimental treatment.
Random Assignment
An effective way of assigning individuals to groups for testing
Example: Echinacea tea experiment:
Hypothesis: drinking Echinacea tea relieves cold symptoms
Experimental group drinks Echinacea tea 5-6 times daily.
Control group drinks “sham” Echinacea tea 5-6 times daily (placebo).
Both groups rated the effectiveness of their treatment on relieving cold symptoms.
Minimizing Bias in Experimental Design
If human subjects know whether they have received the real treatment or a placebo, they may be biased.
Blind experiment: subjects don’t know what kind of treatment they have received
Double blind experiment: the person administering the treatments and the subjects
The scientific method allows the solving of problems and answering of questions.
Observations
Proposing ideas
Testing the ideas
Discarding or modifying ideas based on results
Hypothesis: proposed explanation for a set of observations
Hypotheses needs to be:
Testable – it must be possible to examine the hypothesis through observations
Falsifiable – it must be able to potentially be proven false
Both logical and creative influences are used to develop a hypothesis
A hypothesis that fails our test is rejected and considered disproven.
A hypothesis that passes is supported, but not proven.
Why not? An alternative hypothesis might be the real explanation.
The Experimental Method
Experiments are designed to collect data or information to test specific hypotheses.
Variables: factors that can change in value under different conditions
Independent variables can be manipulated by the scientist
Dependent variables cannot be changed by the researcher
Controlled experiment: tests the effect of a single variable
Control: a subject who is not exposed to the experimental treatment but has all other variables the same
Controlled Experiments
Differences seen between the experimental group and control group can be attributed to the experimental treatment.
Random Assignment
An effective way of assigning individuals to groups for testing
Example: Echinacea tea experiment:
Hypothesis: drinking Echinacea tea relieves cold symptoms
Experimental group drinks Echinacea tea 5-6 times daily.
Control group drinks “sham” Echinacea tea 5-6 times daily (placebo).
Both groups rated the effectiveness of their treatment on relieving cold symptoms.
Minimizing Bias in Experimental Design
If human subjects know whether they have received the real treatment or a placebo, they may be biased.
Blind experiment: subjects don’t know what kind of treatment they have received
Double blind experiment: the person administering the treatments and the subjects