A scientist looked at cells from an onion root tip under a microscope. The scientist counted the number of cells at each stage of the cell cycle.
The Table shows the results.
Table
| Stage of the cell cycle | Number of cells |
|---|---|
| interphase | 180 |
| prophase | 12 |
| metaphase | 4 |
| anaphase | 2 |
| telophase | 2 |
Calculate the percentage of cells that were in interphase.
The time a cell spends in each stage is in proportion to the number of cells counted at that stage.
One cell cycle in these cells takes 20 hours.
Calculate the time that a cell spends in mitosis (prophase to telophase).
Explain why most of the cells counted were in interphase.
Suggest why the scientist used cells from the tip of the root rather than from further up the root.
42 exam-style questions on Edexcel GCSE Biology 2.1 Cell division and growth, covering 2.1.1 Mitosis and the cell cycle, 2.1.2 Division producing identical daughter cells, 2.1.3 Cancer and uncontrolled cell division, 2.1.4 Growth in animals and plants, 2.1.5 Importance of cell differentiation, and 2.1.6 Percentile charts to monitor growth. Each one has a worked solution and a mark scheme showing where the marks go.