A medicine temporarily reduces the rate at which adult stem cells in a person's bone marrow divide. The medicine does not affect mature blood cells directly.
A blood test shows that the person's red blood cell count has decreased. The table shows the person's white blood cell count.
| Time of blood test | White blood cell count (×109 dm−3\times 10^{9}\ \text{dm}^{-3}×109 dm−3) |
|---|---|
| Before taking the medicine | 7.5 |
| While taking the medicine | 4.5 |
Calculate the percentage decrease in the white blood cell count.
Explain why the red blood cell count and white blood cell count decreased and predict what will happen to both counts when the adult stem cells return to their normal rate of division.
194 exam-style questions on OCR GCSE Biology 2.1 Supplying the cell, covering 2.1.1 Transport across cell membranes, 2.1.2 Mitosis and the cell cycle, 2.1.3 Importance of cell differentiation, and 2.1.4 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.