An alga releases molecule Z into pond water. Molecule Z causes some types of bacterium to increase the concentration of substance Y inside their cells.
Researchers expose four bacterial cell types to the same concentration of molecule Z for five minutes.
| Bacterial cell type | Number of protein K molecules per μm² of cell membrane | Increase in concentration of substance Y after five minutes / μmol dm⁻³ |
|---|---|---|
| A | 80 | 24 |
| B | 40 | 12 |
| C | 0 | 0 |
| D | 60 | not measured |
Calculate the expected increase in the concentration of substance Y in cell type D after five minutes.
Explain why cell types A and B respond to molecule Z but cell type C does not.
130 exam-style questions on OCR GCSE Biology 1.1 Cell structures, covering 1.1.1 Viewing cells with light microscopes, 1.1.2 Sub-cellular structures and functions, and 1.1.3 Electron microscopy and resolution. Each one has a worked solution and a mark scheme showing where the marks go.