Question

1. a researcher finds that blood alcohol levels cause progressive damage to the liver. the mice in his study receive the same amount and types of food. different concentrations of alcohol are injected into each mouse. one group of mice does not receive any alcohol at all. the varying concentrations of alcohol injected into different mice represent the ______

a. constant
b. control
c. dependent variable
d. independent variable

Explanation:

To solve this, we analyze each option:

• Option a (constant): A constant is a factor that doesn’t change. Here, alcohol concentration varies, so it’s not a constant.
• Option b (control): The control group is the one with no alcohol (the group not receiving alcohol). The varying alcohol concentrations are not the control.
• Option c (dependent variable): The dependent variable depends on the independent variable (e.g., liver damage depends on alcohol). Alcohol concentration is what’s manipulated, not what’s measured as a result.
• Option d (independent variable): The independent variable is the factor manipulated by the researcher (here, varying alcohol concentrations) to observe its effect on the dependent variable (liver damage).

Answer:

d. independent variable