Scientists place spherical animal cells in three solutions for 10 minutes. They measure the mean diameter of the cells before and after placing them in each solution.
| Solution | Solute concentration (mol dm⁻³) | Mean diameter before (µm) | Mean diameter after 10 minutes (µm) |
|---|---|---|---|
| P | 0.20 | 18.0 | 21.1 |
| Q | 0.35 | 18.1 | 18.1 |
| R | 0.50 | 18.0 | 15.2 |
Explain which solution had the same water potential as the cytoplasm of the cells.
The scientists prepare another solution with a solute concentration of 0.42 mol dm⁻³.
Use the pattern in the results to suggest whether the mean diameter of cells placed in this solution would be greater than, equal to or less than their starting diameter. Explain your answer.
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.