1.1 Cell structure

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Question 29

Medium

A student wants to estimate the concentration of bacteria in a liquid culture using a counting chamber under a microscope. The table below shows the number of bacteria counted in four separate samples using the counting chamber:

Sample	Number of bacteria in counting chamber
1	22
2	18
3	25
4	15

The dimensions of the counting chamber are:

Width: $mm0.2\text{ mm}$
Length: $mm0.2\text{ mm}$
Depth: $mm0.02\text{ mm}$

Calculate the mean number of bacteria in the four samples.

[1]

Calculate the total area of the counting chamber in $mm2\text{mm}^2$ .

[1]

Calculate the volume of the counting chamber in $mm3\text{mm}^3$ using the equation: $volume=area×depth\text{volume} = \text{area} \times \text{depth}$

[1]

Calculate the mean number of bacteria per $mm3\text{mm}^3$ of the culture using the equation: $chamber\text{mean number of bacteria per }\text{mm}^3 = \frac{\text{mean number of bacteria}}{\text{volume of counting chamber}}$

[2]

1.1 Cell structure

Question 29

1.1 Cell structure Questions

1.1 Cell structure

Question 29

1.1 Cell structure Questions