Final answer:
A pregnancy test detects hCG, not GH levels, using a lateral-flow method. If only the control line shows a band in such a test, it indicates a false-positive result. The test relies on capillary action and includes a control strip to ensure its functionality.
Step-by-step explanation:
False. A pregnancy test does not involve antibodies that detect GH levels; it uses antibodies to detect the presence of human chorionic gonadotropin (hCG). hCG is a hormone produced initially by the embryo and later by the placenta. Using a lateral-flow pregnancy test, if a blue band appears on the control line and no band appears on the test line, the test result is a false-positive. This is because the control line indicates that the test is functioning properly, but the absence of a band on the test line indicates no hCG has been detected.
As for the physical process, the lateral flow method requires capillary action to function. The third strip in a lateral flow assay is the control strip which binds beads to prove the test is working correctly. In the context of immunochromatographic assays, antibodies conjugated to small particles, such as colloidal gold, bind the hCG antigen in the sample, and this complex is captured by immobilized anti-hCG antibodies, which create a color change indicating a positive result when hCG is present.