Explain how the pregnancy test strip works to show a positive result.
-urine passes through reaction zone
-HCG hormone binds to the mobile HCG antibody in the reaction zone -passes up the stick
-HCG hormone binds to the immobilised HCG antibodies in the results zone
-the other antibodies which do not attach to HCG
-bind to antibodies in control zone
-blue dye appears in both control and results zones to show positive result