A scientist estimated the number of yeast cells in a culture.
The scientist placed a drop of the culture on a counting slide. The counting slide has a grid of squares. Each square holds 0.004 mm3 of culture.
The scientist counted the yeast cells in five squares.
The Table shows the results.
Table
| Square | Number of yeast cells |
|---|---|
| A | 12 |
| B | 15 |
| C | 9 |
| D | 14 |
| E | 10 |
Calculate the mean number of yeast cells in one square.
Calculate the estimated number of yeast cells in 1 mm3 of the culture on the slide.
The culture had been diluted 10 times before it was placed on the counting slide.
Calculate the estimated number of yeast cells in 1 mm3 of the undiluted culture.
Explain why the scientist counted the yeast cells in five squares rather than in one square.
48 exam-style questions on Edexcel GCSE Biology 1.2 Number, size and scale, covering 1.2.1 Number, size and scale with estimations and 1.2.2 Quantitative units in relation to cells. Each one has a worked solution and a mark scheme showing where the marks go.