A microbiologist is estimating the concentration of yeast cells in a suspension culture using a hemocytometer grid under a light microscope. The table below shows the number of yeast cells counted in four separate grid zones:
| Zone | Number of yeast cells |
|---|---|
| A | 34 |
| B | 29 |
| C | 31 |
| D | 26 |
The dimensions of each grid zone on the hemocytometer are:
Calculate the mean number of yeast cells in the four zones.
Calculate the total area of one grid zone in mm2\text{mm}^2mm2.
Calculate the volume of one grid zone in mm3\text{mm}^3mm3 using the equation:
volume=area×depth \text{volume} = \text{area} \times \text{depth} volume=area×depthCalculate the mean number of yeast cells per mm3\text{mm}^3mm3 of the suspension culture using the equation:
mean number of yeast cells per mm3=mean number of yeast cellsvolume of grid zone \text{mean number of yeast cells per }\text{mm}^3 = \frac{\text{mean number of yeast cells}}{\text{volume of grid zone}} mean number of yeast cells per mm3=volume of grid zonemean number of yeast cells163 exam-style questions on AQA GCSE Biology 1.1 Cell structure, covering 1.1.1 Eukaryotes and prokaryotes, 1.1.2 Animal and plant cells, 1.1.3 Cell specialisation, 1.1.4 Cell differentiation, 1.1.5 Microscopy, and 1.1.6 Culturing microorganisms. Each one has a worked solution and a mark scheme showing where the marks go.