B2 H - Sample set 1 Q6
6) Figure 11 shows the equipment used for measuring respiration in peas.
- Respirometer A contains germinating peas.
- Respirometer B contains peas that are not germinating.
- Respirometer C contains glass beads.
(a) Explain why the respirometers are placed in a water bath at 25°C. (2)
(b) A student recorded the change in oxygen levels in the germinating peas over a 30-minute period.
The results are shown below.
A 10 mins (−0.8) ml, 20 mins (−1.6) ml, 30 mins (−2.4) ml
B 10 mins (−0.1) ml, 20 mins (−0.1) ml, 30 mins (−0.1) ml
C No change
(i) Complete the table for these results. (2)
(ii) Calculate the rate of oxygen consumption per second for the results in respirometer A. (2)
.............................................................. ml/second
(iii) Explain why respirometer A has the highest rate of oxygen consumption. (2)
(c) Some respirometers read the movement of a bubble along capillary tubing.
Carbon dioxide can affect the measuring of oxygen used in this type of respirometer.
State a chemical that could be placed in the respirometer that would stop carbon dioxide affecting the experiment. (1)
(Total for Question 6 = 9 marks)
(c) Some respirometers read the movement of a bubble along capillary tubing.
Carbon dioxide can affect the measuring of oxygen used in this type of respirometer.
State a chemical that could be placed in the respirometer that would stop carbon dioxide affecting the experiment. (1)
(Total for Question 6 = 9 marks)