# Explain how monoclonal antibodies can be used in a pregnancy test to detect whether a woman is pregnant.

> AQA A-Level Biology (7402) — 3.2.4 Cell Recognition and the Immune System · Explain · 5 marks

> Pregnancy tests detect a hormone called human chorionic gonadotropin (hCG), which is only present in the urine of pregnant women. Monoclonal antibodies specific to hCG are used in these tests.

## Mark scheme (5 marks)

1. Monoclonal antibodies are produced to be specific / complementary to hCG (the antigen)
2. hCG in the urine binds to / attaches to the monoclonal antibodies
3. The antibodies are attached to / linked to a coloured marker / dye / indicator
4. If hCG is present, the antibody–antigen complex moves to / collects at a specific region and produces a colour change / visible result / positive result
5. If hCG is absent (woman is not pregnant) no colour change / no visible result / negative result is produced

## Key terms

- [monoclonal antibodies](https://www.gradenine.co.uk/glossary/monoclonal-antibodies)

## Related

- [Revision notes for AQA A-Level Biology (7402)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-monoclonal-antibodies-can-be-cab03be9) · Published by Druglandscape Ltd.