A scientist adds three labelled substances to the liquid surrounding a sample of animal cells. The labels allow any of the substance that enters the cells to be detected.
The results after 10 minutes are shown in the table.
| Substance added | Label detected inside the cells after 10 minutes |
|---|---|
| oxygen | yes |
| protein | no |
| starch | no |
Explain the pattern of results.
In a second investigation, the scientist finds that cells with damaged cell membranes have lower enzyme activity. Suggest why.
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.