Question 67
HA student investigated the growth of a bacterium in nutrient broth. The student counted the number of bacteria every 30 minutes. The results are shown in the table.
Table: The number of bacteria in the broth over 150 minutes
| Time / minutes | Number of bacteria |
|---|---|
| 0 | 1.0 × 103 |
| 30 | 2.0 × 103 |
| 60 | 4.0 × 103 |
| 90 | 8.0 × 103 |
| 120 | 1.6 × 104 |
| 150 | 3.2 × 104 |
a.[1]
Determine the mean division time of this bacterium.
b.[1]
Calculate the number of divisions that would take place in 6 hours.
c.[2]
Calculate the number of bacteria present after 6 hours. Give your answer in standard form.
d.[4]
Figure: Grid for plotting the data in the table
Complete the figure. You should:
-
label the y-axis
-
add the correct scale to the y-axis
-
plot the data from the table
-
draw a curve of best fit.
The point for 0 minutes has been plotted for you.
e.[2]
Describe the shape of the curve you have drawn.
f.[2]
The student left the culture for a further 24 hours. The number of bacteria counted was far lower than the number predicted using the mean division time.
Suggest two reasons for this.
1.1 Cell structure Questions
163 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.