Final answer:
A "controlled" substance is regulated by law due to potential risks. In experiments, controls like controlled variables and control groups ensure valid results.
Step-by-step explanation:
When a substance is classified as "controlled," it typically means that its use, distribution, and possession are governed by legal regulations due to potential risks or concerns associated with it. For example, controlled substances may include drugs that have a potential for abuse or dependence, and thus they are regulated to prevent misuse. This relates to the broader concept of experiment control, which is critical in scientific inquiries to ensure the validity of results.
In an experimental context, a controlled variable refers to a component of the study or experiment that is kept constant to avoid influencing the outcome. A control group is used as a benchmark to compare against other subjects receiving an experimental treatment. Understanding the controls in an experiment is essential for establishing causal relationships.