A ________ is a group in which no response is expected.

• A. Positive control
• B. Negative control
• C. Experimental group
• D. Baseline measurement

Answer: (B)

In experiments, a negative control is a group where no response is expected. This serves as a baseline to show what happens without the experimental variable, helping you distinguish real effects from background changes or contamination. If the negative control shows no response, you can trust that observed effects in the treated groups are due to the variable you introduced.

For example, in a drug study, the negative control might receive a placebo, so there’s no active treatment and no expected therapeutic effect. A positive control, in contrast, would receive a treatment already known to produce a response, confirming that the assay can detect an effect. An experimental group would receive the new treatment being tested. A baseline measurement is a starting value used for comparison, not a group that is tested for a response on its own.

Therefore, the group where no response is expected is the negative control.