The table shows the concentration of calcium ions and sulfate ions inside a freshwater algal cell and in the surrounding pond water.
| Location | Ion concentration in mg per dm3\text{mg per dm}^3mg per dm3 (Calcium) | Ion concentration in mg per dm3\text{mg per dm}^3mg per dm3 (Sulfate) |
|---|---|---|
| In the algal cell | 1824 | 2052 |
| In the pond water | 32 | 18 |
(i) The ratio for the concentration of calcium ions in the algal cell compared to the pond water is 57:157:157:1. Calculate the ratio for the concentration of sulfate ions in the algal cell compared to the pond water.
(ii) When organic waste is discharged into the pond, microbial decomposition rapidly depletes the dissolved oxygen in the water. Suggest why this prevents the algal cells from absorbing calcium or sulfate ions.
Complete the table below by naming a biological molecule that is made in plants using each of the mineral ions.
| Mineral ion | Molecule made using the mineral ion |
|---|---|
| phosphate | |
| nitrogen |
23 exam-style questions on Edexcel IGCSE Biology Movement of substances into and out of cells. Each one has a worked solution and a mark scheme showing where the marks go.