Advanced Placement (AP) Biology Practice Exam

What distinguishes a treatment group from a control group?

1. The treatment group is not exposed to any variables

2. The treatment group receives the experimental manipulation

3. The treatment group has more subjects

4. The treatment group is only used for statistical analysis

The correct answer is: The treatment group receives the experimental manipulation

The distinguishing factor of a treatment group is that it receives the experimental manipulation, which is the specific intervention or treatment that researchers are investigating to observe its effects. This group is exposed to the variable being tested, allowing scientists to collect data on how the treatment impacts certain outcomes compared to the control group, which does not receive this treatment and serves as a baseline for comparison. By having a treatment group that experiences the experimental conditions, researchers can ascertain whether any observed changes are due to the treatment rather than other external factors. This setup is crucial to establishing cause-and-effect relationships in scientific research. Other options do not accurately reflect the role of a treatment group; for instance, the control group is specifically designated to aid in understanding the effects of the treatment by remaining unexposed to the experimental variable, and there is no requirement for the treatment group to have more subjects than the control group.