What is the primary purpose of including positive and negative controls in biochemical tests?

What is the primary purpose of including positive and negative controls in biochemical tests?

• A. To calibrate the instrument only.
• B. To verify that reagents work and to detect contamination or erroneous results.
• C. To speed up the assay.
• D. To eliminate the need for test samples.

Answer: (B)

Including positive and negative controls provides a way to verify that an assay is working properly and to catch problems that would make results unreliable. A positive control uses a sample known to produce a positive result, showing that the reagents, conditions, and detection method can detect the target when it is present. If the positive control fails to give the expected result, you know the test run isn’t trustworthy and you should not trust the other results from that run. A negative control contains everything except the target (or a condition known to be free of the target) to reveal any background signal, contamination, or non‑specific reactions. If the negative control shows a signal, it indicates contamination or interference that could lead to false positives or misinterpretation of true results. Together, these controls anchor interpretation: when the positive control works and the negative control remains clean, you can trust the test results for real samples. They verify that reagents are functioning and that there isn’t contamination or erroneous results. Calibrating the instrument, speeding up the assay, or eliminating the need for test samples aren’t the primary roles of these controls; their main purpose is to ensure the assay’s reliability and validity.

Including positive and negative controls provides a way to verify that an assay is working properly and to catch problems that would make results unreliable. A positive control uses a sample known to produce a positive result, showing that the reagents, conditions, and detection method can detect the target when it is present. If the positive control fails to give the expected result, you know the test run isn’t trustworthy and you should not trust the other results from that run.

A negative control contains everything except the target (or a condition known to be free of the target) to reveal any background signal, contamination, or non‑specific reactions. If the negative control shows a signal, it indicates contamination or interference that could lead to false positives or misinterpretation of true results.

Together, these controls anchor interpretation: when the positive control works and the negative control remains clean, you can trust the test results for real samples. They verify that reagents are functioning and that there isn’t contamination or erroneous results.

Calibrating the instrument, speeding up the assay, or eliminating the need for test samples aren’t the primary roles of these controls; their main purpose is to ensure the assay’s reliability and validity.