5. A researcher finds that blood alcohol levels cause progressive damage to the liver. All the mice in his study were fed the same amount and types of food. Different concentrations of alcohol were injected into each mouse. One group of mice does not receive any alcohol at all. The different concentration of alcohol injected into different mice represents the ______________________.
A.
constant
B.
dependent variable
C.
independent variable
D.
control
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
With this information, you should be able to decide.
D. control
C. independent variable
The different concentrations of alcohol injected into different mice represents the independent variable in this study. The independent variable is the one that is manipulated by the researcher to see its effect on the dependent variable. In this case, the researcher wants to see the effect of alcohol concentration on the liver damage, so they are changing the concentration of alcohol injected into the mice, making it the independent variable.