The figure shows the inside of the strip from a home pregnancy test. The antibodies that can move along the strip are joined to blue beads. A second set of antibodies is fixed to the strip at the test line.
Figure: The inside of the strip from a home pregnancy test

Explain why a blue line appears at the test line when HCG is present in the urine.
Explain why no blue line appears at the test line when HCG is absent from the urine.
The antibodies used in the test are monoclonal. Explain why this is important.
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.