Scientists are testing treatment A for a type of cancer. The treatment contains a monoclonal antibody that binds to antigen R on the cell membrane. The antibody carries a chemical that stops cells growing and dividing.
The scientists put 1.0 million cells into each culture. They added the same concentration of treatment A to some cultures for 48 hours and kept other cultures untreated for comparison.
The results are shown in the table.
| Cell culture | Antigen R on cell membrane? | Number of cells after 48 hours without treatment in millions | Number of cells after 48 hours with treatment A in millions |
|---|---|---|---|
| Cancer cells from the type being treated | Yes | 4.0 | 1.3 |
| Healthy cells from the same tissue | No | 3.8 | 3.6 |
| Cancer cells from a different type of cancer | No | 4.1 | 4.0 |
Explain how the results support the use of treatment A.
Suggest why treatment A might become less effective if the cancer cells produced less antigen R on their cell membranes.
The scientists test treatment B under the same conditions. Treatment B contains a different monoclonal antibody carrying the same chemical.
| Cell culture | Number of cells after 48 hours with treatment A in millions | Number of cells after 48 hours with treatment B in millions |
|---|---|---|
| Cancer cells from the type being treated | 1.3 | 1.6 |
| Healthy cells from the same tissue | 3.6 | 2.4 |
Which treatment shows better targeting of the cancer cells?
Justify your answer.
60 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.