In a home pregnancy test, antibodies carrying a coloured bead can move along the strip. A second set of antibodies is fixed in place at the test line. A coloured line appears at the test line because
the antibodies carrying the beads bind to the fixed antibodies there
the fixed antibodies release the coloured beads that they have stored
HCG links the antibodies carrying the beads to the fixed antibodies
HCG breaks open the coloured beads and releases the dye they hold
42 exam-style questions on AQA GCSE Biology 3.2 Monoclonal antibodies (HT only), covering 3.2.1 Producing monoclonal antibodies and 3.2.2 Uses of monoclonal antibodies. Each one has a worked solution and a mark scheme showing where the marks go.