Figure 2 shows the materials used in a test for PSA.
In the PSA test, the blood sample is added to the well. After 60 minutes, the well is washed out.
Then, antibodies against PSA with enzyme A attached are added to the well.
After 30 minutes, the well is washed out again. Finally, substrate A is added. I800000 ninom
In a negative test, the end solution is colourless. In a positive test, the end solution is blue.
2.2* Explain how the PSA test can be used to test for prostate cancer. (6)