Other than those stated, suggest two variables the student should have kept constant in this investigation.

1

2

Describe how the student used the apparatus in Figure 1 to reset the drop of coloured liquid back to the right-hand end of the tubing.

The student also set up a control experiment.

Suggest a suitable control experiment and explain why it was necessary.

Control experiment

Explanation

Figure 2 shows the student's results at 25 °C

The mass of the woodlice in the tube was 3.78 g

Use Figure 1 (on page 4) and Figure 2 to calculate the mean rate of oxygen uptake by the woodlice in mm3 s–1 g–1

The formula for the volume of the capillary tubing is π r2 l.

Use π = 3.14 in your calculation.

Show your working and give your answer to 2 decimal places.

Answer ______________ mm3 s–1 g–1