1.1 Cell structure

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Question 24
Medium

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:

ZoneNumber of yeast cells
A34
B29
C31
D26

The dimensions of each grid zone on the hemocytometer are:

  • Width: 0.25 mm0.25\text{ mm}0.25 mm
  • Length: 0.25 mm0.25\text{ mm}0.25 mm
  • Depth: 0.08 mm0.08\text{ mm}0.08 mm
a.

Calculate the mean number of yeast cells in the four zones.

[2]
b.

Calculate the total area of one grid zone in mm2\text{mm}^2mm2.

[1]
c.

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×depth

[1]
d.

Calculate 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 cells​

[2]

1.1 Cell structure Questions

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